http 发送post请求

/*
* http发送post请求
*/
public static void  main(String args[]){

        try {

            String obj = "";  //请求发送的数据  ，json格式

            JSONObject ob = new JSONObject(obj); //转成json对象

            System.out.println(ob);

            URL url = new URL("http://ip地址 ：端口号/项目地址");   //要访问的地址路径

            HttpURLConnection conn = (HttpURLConnection) url.openConnection();

            conn.setDoOutput(true);

            conn.setDoInput(true);

            conn.setUseCaches(false);

            conn.setRequestMethod("POST");  //请求方式是get 还是post。

            conn.setRequestProperty("Connection", "Keep-Alive");

            conn.setRequestProperty("Charset", "UTF-8");  //设置编码格式

            byte[] data = (obj.toString()).getBytes();

            conn.setRequestProperty("Content-Length", String.valueOf(data.length));

            conn.setRequestProperty("contentType", "application/json");

            conn.connect();

            OutputStream  out = conn.getOutputStream();     

            out.write((obj.toString()).getBytes());

            out.flush();

            out.close();

            System.out.println(conn.getResponseCode());

            if (conn.getResponseCode() == 200) {

                System.out.println("");

                InputStream in = conn.getInputStream();

                String a = null;

                try {

                    byte[] data1 = new byte[in.available()];

                    in.read(data1);

                    a = new String(data1);

                    System.out.println(a);

                } catch (Exception e1) {

                    // TODO Auto-generated catch block

                    e1.printStackTrace();

                }

            } else {

                System.out.println("no++");

            }

        } catch (Exception e) {

        }

    }