Java模拟post请求

private String getApiReply(){
String responseStr="";
try{
URL url = new URL("http://www.****");
    HttpURLConnection httpConn = (HttpURLConnection)url.openConnection();
        httpConn.setRequestMethod("POST");
        httpConn.setRequestProperty("Content-type", "application/json");
        //httpConn.s
        httpConn.setDoOutput(true);
        StringBuffer xml=new StringBuffer();
        byte[] b = xml.toString().getBytes();//和get的方法一样的
        httpConn.getOutputStream().write(b, 0, b.length);
        httpConn.getOutputStream().flush();
        httpConn.getOutputStream().close();
    //获得服务器返回的数据
        InputStreamReader l_urlStream = new InputStreamReader(httpConn.getInputStream(), "UTF-8"); 
BufferedReader l_reader = new BufferedReader(l_urlStream); 
    String sCurrentLine="";
    while ((sCurrentLine = l_reader.readLine()) != null) {  
    responseStr += sCurrentLine;  
    }
}catch(Exception e){
e.printStackTrace();
}
return responseStr;
}