使用UrlConnection实现后台模拟http请求的简单实例

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"); 
  } 
} 

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