使用UrlConnection实现后台模拟http请求的简单实例

使用UrlConnection实现后台模拟http请求的简单实例

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。

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