Volley的使用以及源码分析（一）
2016-07-11 10:36
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一、Volley的使用
1.1 Volley简介
Volley是Google I/O 2013发布的一款基于Android平台的网络框架,它的优点有： 1) 默认Android2.3及以上基于 HttpURLConnection,2.3以下基于HttpClient;
2) 提供了两种缓存机制：磁盘缓存和内存缓存,符合Http缓存语义的缓存机制;
3) 支持指定请求的优先级;
4) 提供多样的取消机制：特定任务取消以及多任务取消;
5) 提供简便的图片加载工具（ImageRequest、ImageLoader）;
6) 一个优秀的框架.
不足之处：它只适应数据量小,通信频繁的网络操作,如果数据量大如音频、视频等传输,就不要使用Volley为好.下图是官方给出的Velloy网络框架示意图,就表明该框架适合数据量不大但很频繁的场景.
1.2 获取Volley
1) 可以直接从google上git clone下来: git clone https://android.googlesource.com/platform/frameworks/volley
然后使用命令：android update project -p . ant jar生成一个Volley.jar包,直接添加到工程中就可以使用了.
2) 或者从github上下载源码
https://github.com/Fox-Legend/android-volley
1.3 使用Volley
Volley中构建了很多工具网络请求工具类,如StringRequest、JsonArrayRequest、JsonObjectRequest、ImageRequest等,这些都是常用的网络请求. Volley提供了一个请求队列RequestQueue专门用于存放用户的网络请求,所有的request申请后都添加到这个队列中缓存,然后按照一定的算法并发地发出这些请求,
一般网络请求队列在整个APP内使用是一个全局对象,所以最好写到Application中,
<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">AppApplication</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Application</span> {</span>
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 建立请求队列
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> RequestQueue mQueue;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onCreate();
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>.mQueue = Volley.newRequestQueue(getApplicationContext());
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> RequestQueue <span class="hljs-title" style="box-sizing: border-box;">getRequestQueue</span>(){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> mQueue;
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li></ul>在创建RequestQueue队列对象的构造函数中,已经调用了RequestQueue的start方法.
对应的需要修改AndroidManifest.xml文件,是的App对应的Application对象为AppApplication.
不要忘记添加访问网络的权限：
<code class="hljs perl has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><application android:name=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">".AppApplication"</span> android:allowBackup=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"true"</span> android:icon=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@mipmap</span>/ic_launcher"</span> android:label=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@string</span>/app_name"</span> android:supportsRtl=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"true"</span> android:theme=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"<span class="hljs-variable" style="color: rgb(102, 0, 102); box-sizing: border-box;">@style</span>/AppTheme"</span>> <activity android:name=<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">".MainActivity"</span>></code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li></ul>
(1) 建立一个JsonArrayRequest发送Http请求,并添加到RequestQueue中,返回Json数据:
<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">static</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String TAG = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"MainActivity"</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> String mUrl = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://10.8.204.173:5000/shouye/newdata/1"</span>;
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onCreate</span>(Bundle savedInstanceState) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);
VolleyGet();
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 网络请求方式为Get，返回Json
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">VolleyGet</span>() {
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 建立JsonArrayRequest请求
*/</span>
JsonArrayRequest request = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> JsonArrayRequest(Request.Method.GET,mUrl,<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Response.Listener<JSONArray>() {
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onResponse</span>(JSONArray response) {
Toast.makeText(MainActivity.<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>,<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"the response:"</span> + response.toString(),Toast.LENGTH_SHORT).show();
}
}, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Response.ErrorListener() {
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onErrorResponse</span>(VolleyError error) {
Log.e(TAG,error.toString());
}
});
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 为request设置请求标签
*/</span>
request.setTag(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JSONArrayRequest_GET"</span>);
AppApplication.getRequestQueue().add(request);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li></ul>返回Json数据：
the response:
[{“star”:”53”,”date”:”06-18”,”title”:”美发图片长发卷发”,”urls”:[“http:\/\/t1.du114.com\/uploads\/tu\/201606\/changfa250\/2008111233241866_2.jpg”]}]
大家都知道Http的请求类型通常有两种,GET和POST,上面只是使用GET方式,若想要发送POST请求,只需要修改method==Request.Method.POST即可,再加添post请求内容params.
JsonArrayRequest其对应的构造函数参数列表为：
<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">/* 默认的请求方法是GET
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">JsonArrayRequest</span>(String url, Listener<JSONArray> listener, ErrorListener errorListener) {
...<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 省略代码</span>
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* Creates a new request.
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> method the HTTP method to use：网络请求的方法,如GET和POST等
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> url URL to fetch the JSON from：网络请求的地址
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> jsonRequest A {@link JSONArray} to post with the request. Null is allowed and
* indicates no parameters will be posted along with request
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> listener Listener to receive the JSON response：请求返回结果监听
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> errorListener Error listener, or null to ignore errors.：请求失败监听
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">JsonArrayRequest</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> method, String url, JSONArray jsonRequest,
Listener<JSONArray> listener, ErrorListener errorListener) {
...<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">// 省略代码</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li></ul>总结上述过程总共就三步：
a、创建一个RequestQueue对象;
b、创建一个JsonArrayRequest对象;
c、将JsonArrayRequest对象添加到RequestQueue中.
在Volley中还提供了其它的Request,比如StringRequest/JsonObjectRequest等,而且还可以自定义Request.使用方法基本和上述一样.
(2) 除了一些基本字符数据的网络请求,Volley还可以加载图片数据,有两种请求方式：ImageLoader和ImageRequest
ImageRequest
ImageRequest和之前的request用法差不多,都是在创建对象后添加到RequestQueue中.
<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 利用ImageRequest加载图片
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">VolleyImageRequest</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> ImageView imageView) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxHeight = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">480</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxWidth = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">640</span>;
String mPicUrl = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://t1.du114.com/uploads/tu/201510/fengjing/rgj5thjkwlf.jpg"</span>;
ImageRequest imgRequest = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ImageRequest(mPicUrl, <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Response.Listener<Bitmap>() {
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onResponse</span>(Bitmap response) {
imageView.setImageBitmap(response);
}
}, maxWidth, maxHeight,ImageView.ScaleType.CENTER, Bitmap.Config.RGB_565,
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> Response.ErrorListener() {
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onErrorResponse</span>(VolleyError error) {
Log.e(TAG,error.toString());
}
});
imgRequest.setTag(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"ImageRequest_TAG"</span>);
AppApplication.getRequestQueue().add(imgRequest);
}
</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li></ul>可以看到，ImageRequest的构造函数能接收七个参数(原有的六个参数的方法最后也是调用该方法),第一个参数就是图片的URL地址。第二个参数是图片请求成功的回调, 这里我们可以把返回的Bitmap参数设置到ImageView中,第三第四个参数分别用于指定允许图片最大的宽度和高度,如果指定的网络图片的宽度或高度大于这里的最大值,则会对图片进行压缩，指定成0的话就表示不管图片有多大,都不会进行压缩. 第五个参数用于指定图片填充空间的缩放方式ScaleType,第六个参数用于指定图片的颜色属性,Bitmap.Config下的几个常量都可以在这里使用，其中ARGB_8888可以展示最好的颜色属性，每个图片像素占据4个字节的大小，而
RGB_565则表示每个图片像素占据2个字节大小。第七个参数是图片请求失败的回调，这里我们可以在请求失败时在ImageView中显示一张默认图片。
ImageLoader
ImageLoader也可以用于加载网络图片,并且内部也是使用ImageRequest来实现的,不过ImageLoader比ImageRequest要高效,因为它不仅可以对图片进行缓存而且还可以过滤重复的链接,避免重复发送请求.
<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 利用ImageLoader加载图片
*<span class="hljs-javadoctag" style="color: rgb(102, 0, 102); box-sizing: border-box;"> @param</span> mImgView
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">VolletImageLoader</span>(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> ImageView mImgView) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxHeight = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">480</span>;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxWidth = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">640</span>;
String mPicUrl = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://t1.du114.com/uploads/tu/201510/fengjing/rgj5thjkwlf.jpg"</span>;
ImageLoader imgLoader = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ImageLoader(AppApplication.getRequestQueue(),<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> BitmapCache());
ImageLoader.ImageListener listener =
ImageLoader.getImageListener(mImgView,android.R.drawable.ic_menu_rotate,android.R.drawable.ic_delete);
imgLoader.get(mPicUrl,listener,maxWidth,maxHeight);
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* BitmapCache
*/</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">BitmapCache</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">implements</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ImageLoader</span>.<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">ImageCache</span> {</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> LruCache<String,Bitmap> mCache;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-title" style="box-sizing: border-box;">BitmapCache</span>(){
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> maxSize = <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">10</span> * <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1024</span> * <span class="hljs-number" style="color: rgb(0, 102, 102); box-sizing: border-box;">1024</span>;
mCache = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> LruCache<String,Bitmap>(maxSize){
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">int</span> <span class="hljs-title" style="box-sizing: border-box;">sizeOf</span>(String key, Bitmap value) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> value.getRowBytes() * value.getHeight();
}
};
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> Bitmap <span class="hljs-title" style="box-sizing: border-box;">getBitmap</span>(String url) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> mCache.get(url);
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">public</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">putBitmap</span>(String url, Bitmap bitmap) {
mCache.put(url,bitmap);
}
} </code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul>可以看到，ImageLoader的构造函数接收两个参数，第一个参数就是RequestQueue对象，第二个参数是一个ImageCache对象，我们通过调用ImageLoader的getImageListener()方法能够获取到一个ImageListener对象，getImageListener()方法接收三个参数，第一个参数指定用于显示图片的ImageView控件，第二个参数指定加载图片的过程中显示的图片，第三个参数指定加载图片失败的情况下显示的图片。最后，调用ImageLoader的get()方法来加载图片。
Volley还特别为加载网络图片提供了NetworkImageView控件(其继承至ImageView),它将上述单独为ImageView设置加载时图片和加载失败的图片等功能封装在一起,更方便.
<code class="hljs avrasm has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;">private void VolleyImageLoader(NetworkImageView mNetworkView) {
String mPicUrl = <span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"http://t1.du114.com/uploads/tu/201510/fengjing/rgj5thjkwlf.jpg"</span><span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
ImageLoader imgLoader = new ImageLoader(AppApplication<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.getRequestQueue</span>(),new BitmapCache())<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.mNetworkView</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setDefaultImageResId</span>(android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.R</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.drawable</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ic</span>_menu_rotate)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.mNetworkView</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setErrorImageResId</span>(android<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.R</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.drawable</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.ic</span>_delete)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
this<span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.mNetworkView</span><span class="hljs-preprocessor" style="color: rgb(68, 68, 68); box-sizing: border-box;">.setImageUrl</span>(mPicUrl,imgLoader)<span class="hljs-comment" style="color: rgb(136, 0, 0); box-sizing: border-box;">;</span>
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li></ul>
1.4 自定义Request
Volley允许用户按照自己的意愿定义特定的Request,那么怎么样去定义了？ 在Volley中的所有Request都是继承至抽象类Request: 如StringRequest:
<code class="hljs scala has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* A canned request for retrieving the response body at a given URL as a String.
*/</span>
public <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">StringRequest</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Request</span><<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">String</span>> {</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> Listener<String> mListener;
public StringRequest(int method, String url, Listener<String> listener,
ErrorListener errorListener) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(method, url, errorListener);
mListener = listener;
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> void onFinish() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onFinish();
mListener = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>;
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> void deliverResponse(String response) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">if</span> (mListener != <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">null</span>) {
mListener.onResponse(response);
}
}
<span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 解析网络请求返回数据
*/</span>
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> Response<String> parseNetworkResponse(NetworkResponse response) {
String parsed;
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
parsed = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String(response.data, HttpHeaderParser.parseCharset(response.headers));
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (UnsupportedEncodingException e) {
parsed = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String(response.data);
}
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> Response.success(parsed, HttpHeaderParser.parseCacheHeaders(response));
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li></ul>若我们想要自定义一个XML文件的XmlRequest,利用XmlPullParserFactory和XmlPullParser去将返回的xml数据进行解析：
<code class="hljs scala has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"><span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* XmlRequest
*/</span>
public <span class="hljs-class" style="box-sizing: border-box;"><span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">class</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">XmlRequest</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">extends</span> <span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">Request</span><<span class="hljs-title" style="box-sizing: border-box; color: rgb(102, 0, 102);">XmlPullParser</span>> {</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">private</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">final</span> Response.Listener<XmlPullParser> mListener;
public XmlRequest(int method, String url, Response.Listener<XmlPullParser> listener,
Response.ErrorListener errorListener) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>(method, url, errorListener);
mListener = listener;
}
public XmlRequest(String url, Response.Listener<XmlPullParser> listener, Response.ErrorListener errorListener) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">this</span>(Method.GET, url, listener, errorListener);
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> Response<XmlPullParser> parseNetworkResponse(NetworkResponse response) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">try</span> {
String xmlString = <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> String(response.data,
HttpHeaderParser.parseCharset(response.headers));
XmlPullParserFactory factory = XmlPullParserFactory.newInstance();
XmlPullParser xmlPullParser = factory.newPullParser();
xmlPullParser.setInput(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> StringReader(xmlString));
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> Response.success(xmlPullParser, HttpHeaderParser.parseCacheHeaders(response));
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (UnsupportedEncodingException e) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> Response.error(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ParseError(e));
} <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">catch</span> (XmlPullParserException e) {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">return</span> Response.error(<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">new</span> ParseError(e));
}
}
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> void deliverResponse(XmlPullParser response) {
mListener.onResponse(response);
}
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li><li style="box-sizing: border-box; padding: 0px 5px;">10</li><li style="box-sizing: border-box; padding: 0px 5px;">11</li><li style="box-sizing: border-box; padding: 0px 5px;">12</li><li style="box-sizing: border-box; padding: 0px 5px;">13</li><li style="box-sizing: border-box; padding: 0px 5px;">14</li><li style="box-sizing: border-box; padding: 0px 5px;">15</li><li style="box-sizing: border-box; padding: 0px 5px;">16</li><li style="box-sizing: border-box; padding: 0px 5px;">17</li><li style="box-sizing: border-box; padding: 0px 5px;">18</li><li style="box-sizing: border-box; padding: 0px 5px;">19</li><li style="box-sizing: border-box; padding: 0px 5px;">20</li><li style="box-sizing: border-box; padding: 0px 5px;">21</li><li style="box-sizing: border-box; padding: 0px 5px;">22</li><li style="box-sizing: border-box; padding: 0px 5px;">23</li><li style="box-sizing: border-box; padding: 0px 5px;">24</li><li style="box-sizing: border-box; padding: 0px 5px;">25</li><li style="box-sizing: border-box; padding: 0px 5px;">26</li><li style="box-sizing: border-box; padding: 0px 5px;">27</li><li style="box-sizing: border-box; padding: 0px 5px;">28</li><li style="box-sizing: border-box; padding: 0px 5px;">29</li><li style="box-sizing: border-box; padding: 0px 5px;">30</li><li style="box-sizing: border-box; padding: 0px 5px;">31</li><li style="box-sizing: border-box; padding: 0px 5px;">32</li><li style="box-sizing: border-box; padding: 0px 5px;">33</li><li style="box-sizing: border-box; padding: 0px 5px;">34</li><li style="box-sizing: border-box; padding: 0px 5px;">35</li><li style="box-sizing: border-box; padding: 0px 5px;">36</li><li style="box-sizing: border-box; padding: 0px 5px;">37</li><li style="box-sizing: border-box; padding: 0px 5px;">38</li></ul>XmlRequest的使用方法和Volley自带的Request差不多.
1.4 取消请求Request
当Activity销毁时,我们可能需要取消一些请求,这时候可以根据在创建Request时,为Request添加的Tag来取消对应的请求,在onDestroy()方法中填写如下代码：<code class="hljs java has-numbering" style="display: block; padding: 0px; background-color: transparent; color: inherit; box-sizing: border-box; font-family: 'Source Code Pro', monospace;font-size:undefined; white-space: pre; border-top-left-radius: 0px; border-top-right-radius: 0px; border-bottom-right-radius: 0px; border-bottom-left-radius: 0px; word-wrap: normal; background-position: initial initial; background-repeat: initial initial;"> <span class="hljs-javadoc" style="color: rgb(136, 0, 0); box-sizing: border-box;">/**
* 为request设置请求标签
*/</span>
request.setTag(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JSONArrayRequest_GET"</span>);
<span class="hljs-annotation" style="color: rgb(155, 133, 157); box-sizing: border-box;">@Override</span>
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">protected</span> <span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">void</span> <span class="hljs-title" style="box-sizing: border-box;">onDestroy</span>() {
<span class="hljs-keyword" style="color: rgb(0, 0, 136); box-sizing: border-box;">super</span>.onDestroy();
AppApplication.getRequestQueue().cancelAll(<span class="hljs-string" style="color: rgb(0, 136, 0); box-sizing: border-box;">"JSONArrayRequest_GET"</span>);
}</code><ul class="pre-numbering" style="box-sizing: border-box; position: absolute; width: 50px; background-color: rgb(238, 238, 238); top: 0px; left: 0px; margin: 0px; padding: 6px 0px 40px; border-right-width: 1px; border-right-style: solid; border-right-color: rgb(221, 221, 221); list-style: none; text-align: right;"><li style="box-sizing: border-box; padding: 0px 5px;">1</li><li style="box-sizing: border-box; padding: 0px 5px;">2</li><li style="box-sizing: border-box; padding: 0px 5px;">3</li><li style="box-sizing: border-box; padding: 0px 5px;">4</li><li style="box-sizing: border-box; padding: 0px 5px;">5</li><li style="box-sizing: border-box; padding: 0px 5px;">6</li><li style="box-sizing: border-box; padding: 0px 5px;">7</li><li style="box-sizing: border-box; padding: 0px 5px;">8</li><li style="box-sizing: border-box; padding: 0px 5px;">9</li></ul>或者若需要取消属于Activity中全部的请求,那么可以为所有属于该Activity的Request添加同样的Tag.
RequestQueue#cancelAll还有另一种重载形式,可以传入RequestFilter,自己指定一个过滤策略.
转自：http://blog.csdn.net/lhqj1992/article/details/51878186
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