向指定Url发送post请求

/**
   * 向指定 URL 发送POST方法的请求
   *
   * @param url 发送请求的 URL
   * @param param 请求参数,json格式，请求参数应该是{name:value1,name2:value2}的形式。
   * @return 所代表远程资源的响应结果
   * @throws IOException
   */
  public static String sendPost(String url, String param) {
    PrintWriter out = null;
    BufferedReader in = null;
    StringBuilder result = new StringBuilder();
    URLConnection conn = null;
    try {
      URL realUrl = new URL(url);
      // 打开和URL之间的连接
      conn = realUrl.openConnection();
      // 设置通用的请求属性
      conn.setRequestProperty("accept", "*/*");
      conn.setRequestProperty("Accept-Charset", "UTF-8");
      conn.setRequestProperty("contentType", "UTF-8");
      conn.setRequestProperty("Accept-Language", Locale.getDefault().toString());
      conn.setRequestProperty("Accept",
          "image/gif, image/jpeg, image/pjpeg, image/pjpeg, application/x-shockwave-flash, application/xaml+xml, application/vnd.ms-xpsdocument, application/x-ms-xbap, application/x-ms-application, application/vnd.ms-excel, application/vnd.ms-powerpoint, application/msword, */*");
      conn.setRequestProperty("Content-Type", "application/json;charset=UTF-8");
      // 发送POST请求必须设置如下两行
      conn.setConnectTimeout(30000);
      conn.setReadTimeout(120000);
      conn.setDoOutput(true);
      conn.setDoInput(true);
      // 获取URLConnection对象对应的输出流
      out = new PrintWriter(new OutputStreamWriter(conn.getOutputStream(), "UTF-8"));
      // out = new PrintWriter(conn.getOutputStream());
      // 发送请求参数
      out.print(param);
      // flush输出流的缓冲
      out.flush();
      // 定义BufferedReader输入流来读取URL的响应
      InputStream stream = conn.getInputStream();
      in = new BufferedReader(new InputStreamReader(stream, "UTF-8"));
      String line;
      while ((line = in.readLine()) != null) {
        result.append(line);
      }
    } catch (Exception e) {
      e.printStackTrace();
      try {
        in = new BufferedReader(new InputStreamReader(((HttpURLConnection) conn).getErrorStream(), "UTF-8"));
        String line;
        while ((line = in.readLine()) != null) {
          result.append(line);
        }
      } catch (IOException e1) {
        e1.printStackTrace();
      }

    } finally {
      try {
        if (out != null) {
          out.close();
        }
        if (in != null) {
          in.close();
        }
      } catch (IOException ex) {
        ex.printStackTrace();
      }
    }
    return result.toString();
  }