java模拟post请求发送json

java模拟http发送请求，第一种是HttpURLConnection发送post请求，第二种是使用httpclient模拟post请求，

方法一：

 package main.utils;

 import java.io.*;
 import java.net.HttpURLConnection;
 import java.net.URL;

 public class HttpUtilTest {
     Log log = new Log(this.getClass());//初始化日志类
     /**
      * @作用 使用urlconnection
      * @param url
      * @param Params
      * @return
      * @throws IOException
      */
     public String sendPost(String url,String Params)throws IOException{
         OutputStreamWriter out = null;
         BufferedReader reader = null;
         String response="";
         try {
             URL httpUrl = null; //HTTP URL类 用这个类来创建连接
             //创建URL
             httpUrl = new URL(url);
             //建立连接
             HttpURLConnection conn = (HttpURLConnection) httpUrl.openConnection();
             conn.setRequestMethod("POST");
             conn.setRequestProperty("Content-Type", "application/json");
             conn.setRequestProperty("connection", "keep-alive");
             conn.setUseCaches(false);//设置不要缓存
             conn.setInstanceFollowRedirects(true);
             conn.setDoOutput(true);
             conn.setDoInput(true);
             conn.connect();
             //POST请求
             out = new OutputStreamWriter(
                     conn.getOutputStream());
             out.write(Params);
             out.flush();
             //读取响应
             reader = new BufferedReader(new InputStreamReader(
                     conn.getInputStream()));
             String lines;
             while ((lines = reader.readLine()) != null) {
                 lines = new String(lines.getBytes(), "utf-8");
                 response+=lines;
             }
             reader.close();
             // 断开连接
             conn.disconnect();

             log.info(response.toString());
         } catch (Exception e) {
         System.out.println("发送 POST 请求出现异常！"+e);
         e.printStackTrace();
         }
         //使用finally块来关闭输出流、输入流
         finally{
         try{
             if(out!=null){
                 out.close();
             }
             if(reader!=null){
                 reader.close();
             }
         }
         catch(IOException ex){
             ex.printStackTrace();
         }
     }

         return response;
     }
 }

　方法二：使用httpclient实现

 import java.io.UnsupportedEncodingException;
 import java.net.URLEncoder;

 import main.utils.Log;

 import org.apache.http.client.methods.CloseableHttpResponse;
 import org.apache.http.client.methods.HttpPost;
 import org.apache.http.entity.ContentType;
 import org.apache.http.entity.StringEntity;
 import org.apache.http.impl.client.CloseableHttpClient;
 import org.apache.http.impl.client.HttpClients;
 import org.apache.http.util.EntityUtils;

 //post请求方法
 public  String sendPost(String url, String data) {
    String response = null;
    log.info("url: " + url);
    log.info("request: " + data);
    try {
        CloseableHttpClient httpclient = null;
        CloseableHttpResponse httpresponse = null;
        try {
            httpclient = HttpClients.createDefault();
            HttpPost httppost = new HttpPost(url);
            StringEntity stringentity = new StringEntity(data,
                    ContentType.create("text/json", "UTF-8"));
            httppost.setEntity(stringentity);
            httpresponse = httpclient.execute(httppost);
            response = EntityUtils
                    .toString(httpresponse.getEntity());
            log.info("response: " + response);
        } finally {
            if (httpclient != null) {
                httpclient.close();
            }
            if (httpresponse != null) {
                httpresponse.close();
            }
        }
    } catch (Exception e) {
        e.printStackTrace();
    }
    return response;
 }

附：httpClient 4.3中文手册，来自开源中国：https://my.oschina.net/u/565871/blog/701214