java调用HTTP接口（Get请求和Post请求）

package com.company;

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

/**
 * 功能简述：
 *
 * @author caidingnu
 * @create 2019/03/27 13:46
 * @since 1.0.0
 */
public class HTTP_Request {
    private static void httpURLGETCase() {
        String methodUrl = "http://127.0.0.1:8099/select_by_id?userid=1";
        HttpURLConnection connection = null;
        BufferedReader reader = null;
        String line = null;
        try {
            URL url = new URL(methodUrl);
            connection = (HttpURLConnection) url.openConnection();// 根据URL生成HttpURLConnection
            connection.setRequestMethod("GET");// 默认GET请求
            connection.connect();// 建立TCP连接
            if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
                reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));// 发送http请求
                StringBuilder result = new StringBuilder();
                // 循环读取流
                while ((line = reader.readLine()) != null) {
                    result.append(line).append(System.getProperty("line.separator"));// "\n"
                }
                System.out.println(result.toString());
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            try {
                reader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
            connection.disconnect();
        }
    }






//Post请求
private static void httpURLPOSTCase() {
    String methodUrl = "http://127.0.0.1:8099/select_by_id?userid=1";
    HttpURLConnection connection = null;
    OutputStream dataout = null;
    BufferedReader reader = null;
    String line = null;
    try {
        URL url = new URL(methodUrl);
        connection = (HttpURLConnection) url.openConnection();// 根据URL生成HttpURLConnection
        connection.setDoOutput(true);// 设置是否向connection输出，因为这个是post请求，参数要放在http正文内，因此需要设为true,默认情况下是false
        connection.setDoInput(true); // 设置是否从connection读入，默认情况下是true;
        connection.setRequestMethod("POST");// 设置请求方式为post,默认GET请求
        connection.setUseCaches(false);// post请求不能使用缓存设为false
        connection.setConnectTimeout(3000);// 连接主机的超时时间
        connection.setReadTimeout(3000);// 从主机读取数据的超时时间
        connection.setInstanceFollowRedirects(true);// 设置该HttpURLConnection实例是否自动执行重定向
        connection.setRequestProperty("connection", "Keep-Alive");// 连接复用
        connection.setRequestProperty("charset", "utf-8");
        connection.setRequestProperty("Content-Type", "application/json");
//        connection.setRequestProperty("Authorization", "Bearer 66cb225f1c3ff0ddfdae31rae2b57488aadfb8b5e7");
        connection.connect();// 建立TCP连接,getOutputStream会隐含的进行connect,所以此处可以不要

        dataout = new DataOutputStream(connection.getOutputStream());// 创建输入输出流,用于往连接里面输出携带的参数
        dataout.flush();
        dataout.close();

        if (connection.getResponseCode() == HttpURLConnection.HTTP_OK) {
            reader = new BufferedReader(new InputStreamReader(connection.getInputStream(), "UTF-8"));// 发送http请求
            StringBuilder result = new StringBuilder();
            // 循环读取流
            while ((line = reader.readLine()) != null) {
                result.append(line).append(System.getProperty("line.separator"));//
            }
            connection.disconnect();  //关闭http连接
            System.out.println(result.toString());
        }
    } catch (IOException e) {
        e.printStackTrace();
    } finally {
        try {
            reader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
        connection.disconnect();
    }
}




public static void main(String[] args){
    HTTP_Request.httpURLPOSTCase();
    HTTP_Request.httpURLGETCase();
}


}