简单的利用UrlConnection，后台模拟http请求

这两天在整理看httpclient，然后想自己用UrlConnection后台模拟实现Http请求，于是一个简单的小例子就新鲜出炉了（支持代理哦）：

public class SimpleHttpTest {

public static String send(String urlStr, Map<String,String> map,String encoding){
String body="";
StringBuffer sbuf = new StringBuffer();
if(map!=null){
for (Entry<String,String> entry : map.entrySet()) {
sbuf.append(entry.getKey()).append("=").append(entry.getValue()).append("&");
}
if(sbuf.length()>0){
sbuf.deleteCharAt(sbuf.length()-1);
}
}
// 1、重新对请求报文进行 GBK 编码
byte[] postData = null;
try {
postData = sbuf.toString().getBytes(encoding);
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}

// 2、发送 HTTP(S) 请求
OutputStream reqStream = null;
InputStream resStream = null;
URLConnection request = null;
try {
System.out.println("交易请求地址：" + urlStr);
System.out.println("参数：" + sbuf.toString());

//A、与服务器建立 HTTP(S) 连接
URL url = null;
try {
Proxy proxy = new Proxy(java.net.Proxy.Type.HTTP,new InetSocketAddress("127.0.0.1", 8087));
url = new URL(urlStr);
request = url.openConnection(proxy);
request.setDoInput(true);
request.setDoOutput(true);
} catch (MalformedURLException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}

//B、指定报文头【Content-type】、【Content-length】 与 【Keep-alive】
request.setRequestProperty("Content-type", "application/x-www-form-urlencoded");
request.setRequestProperty("Content-length", String.valueOf(postData.length));
request.setRequestProperty("Keep-alive", "false");
request.setRequestProperty("User-Agent", "Mozilla/4.0 (compatible; MSIE 5.0; Windows NT; DigExt)");

//C、发送报文至服务器
reqStream = request.getOutputStream();
reqStream.write(postData);
reqStream.close();

//D、接收服务器返回结果
ByteArrayOutputStream ms = null;
resStream = request.getInputStream();
ms = new ByteArrayOutputStream();
byte[] buf = new byte[4096];
int count;
while ((count = resStream.read(buf, 0, buf.length)) > 0) {
ms.write(buf, 0, count);
}
resStream.close();
body = new String(ms.toByteArray(), encoding);
} catch (UnknownHostException e) {
System.err.println( "服务器不可达【" + e.getMessage() + "】");
} catch (IOException e) {
e.printStackTrace();
} finally {
try {
if (reqStream != null)
reqStream.close();
if (resStream != null)
resStream.close();
} catch (Exception ex) {
}
}

System.out.println("交易响应结果：");
System.out.println(body);
return body;
}

public static void main(String[] args) {
String url="http://php.weather.sina.com.cn/iframe/index/w_cl.php";
Map<String, String> map = new HashMap<String, String>();
map.put("code", "js");
map.put("day", "0");
map.put("city", "上海");
map.put("dfc", "1");
map.put("charset", "utf-8");
send(url, map,"utf-8");
}
}

结果如下：

交易请求地址：http://php.weather.sina.com.cn/iframe/index/w_cl.php
参数：dfc=1&charset=utf-8&day=0&code=js&city=上海
交易响应结果：
(function(){var w=[];w['上海']=[{s1:'阴',s2:'阴',f1:'yin',f2:'yin',t1:'17',t2:'14',p1:'≤3',p2:'≤3',d1:'东北风',d2:'东北风'}];var add={now:'2015-11-11 19:04:33',time:'1447239873',update:'北京时间11月11日17:10更新',error:'0',total:'1'};window.SWther={w:w,add:add};})();//0

代码中的步骤写的很明白了，如果你有心，还可以对该方法进行各种封装，方便使用。下篇我会分享一下httpclient是如何模拟后台来发送http请求的，还有配置ssl、代理、自定义header等等，敬请期待吧。