public static void connectionUrl(String username,String password){
        String url = "http://localhost:8080/aaa/bbb.action";

        String responseMessage = ""; 
        StringBuffer response = new StringBuffer(); 
        HttpURLConnection httpConnection = null; 
        OutputStreamWriter out = null
 
; 
        BufferedReader reader = null; 
        try { 
          URL urlPost = new URL(url); 
          httpConnection = (HttpURLConnection) urlPost.openConnection(); 
          httpConnection.setDoOutput(true); 
          httpConnection.setDoInput(true); 
          // 引數長度太大，不能用get方式 
          httpConnection.setRequestMethod("POST"
 
); 
          // 不使用快取 
          httpConnection.setUseCaches(false); 
          // URLConnection.setInstanceFollowRedirects是成員函式，僅作用於當前函式 
          httpConnection.setInstanceFollowRedirects(true); 
          // 配置本次連線的Content-type，配置為application/x-www-form-urlencoded的 
          // 意思是正文是urlencoded編碼過的form引數 
 

          httpConnection.setRequestProperty("Connection", "Keep-Alive");
          // 設定請求頭資訊
          httpConnection.setRequestProperty("Charset", "UTF-8");
          // 設定邊界
          String BOUNDARY = "----------" + System.currentTimeMillis();
          httpConnection.setRequestProperty("Content-Type", "multipart/form-data; boundary=" + BOUNDARY);
          //httpConnection.setRequestProperty("Content-Type", "application/x-www-form-urlencoded"); 

          // 連線，從postUrl.openConnection()至此的配置必須要在connect之前完成， 
          // 要注意的是connection.getOutputStream會隱含的進行connect。 
          // 實際上只是建立了一個與伺服器的tcp連線，並沒有實際傳送http請求。 

          httpConnection.connect(); 
          out = new OutputStreamWriter(httpConnection.getOutputStream(),"UTF-8"); 

          // 正文，正文內容其實跟get的URL中'?'後的引數字串一致 

          /*JSONObject jsonObject=new JSONObject(); 
          try{
              jsonObject.put("username", username); 
              jsonObject.put("password", password); 
              jsonObject.put("captcha", captcha); 
          }catch(Exception e){
              e.printStackTrace();
          }*/
          /*
          Map parames = new HashMap<String, String>();  
            parames.put("username", "username");  
            parames.put("username", "username");  
            parames.put("captcha", "captcha");  
          */
          // 構建請求引數  
            StringBuffer sb = new StringBuffer();  
            sb.append("username="+username+"&password="+password);
          //寫入引數,DataOutputStream.writeBytes將字串中的16位的unicode字元以8位的字元形式寫道流裡面 
          out.write(sb.toString()); 
          System.out.println("send_url:" + url);  
          System.out.println("send_data:" + sb.toString());  
          // flush and close 
          out.flush(); 

        } catch (Exception e) {  
            e.printStackTrace();  
        } finally {  
             try { 
                if (null != out) { 
                  out.close(); 
                } 
                if (null != reader) { 
                  reader.close(); 
                } 
                if (null != httpConnection) { 
                  httpConnection.disconnect(); 
                } 
              } catch (Exception e2) { 
                  e2.printStackTrace();
              }
        }  

        try {
          reader = new BufferedReader(new InputStreamReader(httpConnection.getInputStream(),"UTF-8")); 
          while ((responseMessage = reader.readLine()) != null) { 
              response.append(responseMessage); 
              response.append("\n"); 
          } 

          if (!"failure".equals(response.toString())) { 
              System.out.println("success");
          } else { 
              System.out.println("failue");
          } 
          // 將該url的配置資訊快取起來 
          System.out.println(response.toString()); 
          System.out.println(httpConnection.getResponseCode());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
public static void main(String[] args){
    connectionUrl("張三","123456");
}