查看网络图片功能的应用程序

一：当在EditText中输入地址后，点击浏览按钮，会在EditText上面空白地方显示该地址对应的一张图片。

activity_main布局代码：

1 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
2     xmlns:tools="http://schemas.android.com/tools"
3     android:layout_width="match_parent"
4     android:layout_height="match_parent"
5     android:orientation="vertical"
6     android:paddingBottom="@dimen/activity_vertical_margin"
7     android:paddingLeft="@dimen/activity_horizontal_margin"
8     android:paddingRight="@dimen/activity_horizontal_margin"
9     android:paddingTop="@dimen/activity_vertical_margin"
10     tools:context=".MainActivity" >
11
12     <ImageView
13         android:id="@+id/ivImage"
14         android:layout_width="match_parent"
15         android:layout_height="match_parent"
16         android:layout_gravity="center"
17         android:layout_weight="1"
18         />
19
20     <EditText
21         android:id="@+id/etImageUrl"
22         android:layout_width="match_parent"
23         android:layout_height="wrap_content"
24         android:ems="10"
25         android:hint="请输入图片的地址"
26          >
27
28         <requestFocus />
29     </EditText>
30
31     <Button
32         android:id="@+id/btnView"
33         android:layout_width="278dp"
34         android:layout_height="wrap_content"
35         android:background="@drawable/back_button"
36         android:onClick="showImage"
37         android:text="浏览" />
38
39 </LinearLayout>

MainActivity代码：

1 public class MainActivity extends Activity {
2     Button button;
3     ImageView imageView;
4     EditText ed;
5     private static final int MSG_SUCCESS = 0;// 获取图片成功的标识
6     private static final int MSG_FAILURE = 1;// 获取图片失败的标识
7
8     @Override
9     protected void onCreate(Bundle savedInstanceState) {
10         super.onCreate(savedInstanceState);
11         setContentView(R.layout.activity_main);
12         findView();
13     }
14
15     public void findView() {
16         button = (Button) findViewById(R.id.btnView);
17         imageView = (ImageView) findViewById(R.id.ivImage);
18         ed = (EditText) findViewById(R.id.edt);
19     }
20
21     @Override
22     public boolean onCreateOptionsMenu(Menu menu) {
23         // Inflate the menu; this adds items to the action bar if it is present.
24         getMenuInflater().inflate(R.menu.main, menu);
25         return true;
26     }
27
28     private Handler handler = new Handler(){
29
30         public void handleMessage(Message msg) {
31             switch (msg.what) {
32             case MSG_SUCCESS:
33                 Bitmap bit = (Bitmap) msg.obj;
34                 imageView.setImageBitmap(bit);
35                 break;
36             default:
37                 break;
38             }
39         };
40
41     };
42
43     public void viewImage(View view) {
44
45         final String path = ed.getText().toString();//获取输入的图片路径
46         if (TextUtils.isEmpty(path)) {
47             Toast.makeText(MainActivity.this, " 路径不为空", Toast.LENGTH_SHORT)
48                     .show();
49         } else {
50             new Thread() {
51                 public void run() {
52                     URL url;
53                     try {
54                         url = new URL(path);//发出请求
55                         HttpURLConnection connection = (HttpURLConnection) url
56                                 .openConnection();
57                         connection.setRequestMethod("GET");//设置请求方式这里的方式必须为大写
58                         connection.setConnectTimeout(5000);//设置超时的时间
59                         int code = connection.getResponseCode();//获得状态码
60                         if (code == 200) {
61                             InputStream is = connection.getInputStream();
62                             Bitmap bitmap = BitmapFactory.decodeStream(is);//写入一个bitmap流
63                             Message m = new Message();
64                             m.what = MSG_SUCCESS;
65                             m.obj = bitmap;
66                             handler.sendMessage(m);
67                         } else {
68                             Toast.makeText(MainActivity.this, "打开失败",
69                                     Toast.LENGTH_SHORT).show();
70                         }
71
72                     } catch (MalformedURLException e) {
73                         // TODO Auto-generated catch block
74                         e.printStackTrace();
75                     } catch (IOException e) {
76                         // TODO Auto-generated catch block
77                         e.printStackTrace();
78                     }
79
80                 };
81             }.start();
　　　　　　　　　　　　//必须加start()方法
82         }
83
84     }
85 }

注意：UI线程只允许修改Activity里的UI组件，然后在androidManifest中必须有配置文件。注意开始线程的使用！