Java基础系列：HttpURLConnection请求GET、POST接口

Java请求Http接口常用的方式有三种，如下表

本章讲解：HttpURLConnection，该类继承URLConnection。

package com.monkey.java_study.web;

import com.google.gson.Gson;
import com.monkey.java_study.common.constant.BooleanConstant;
import com.monkey.java_study.common.constant.WebConstant;
import com.monkey.java_study.common.entity.PageEntity;
import org.apache.logging.log4j.LogManager;
import org.apache.logging.log4j.Logger;

import java.io.BufferedReader;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.net.HttpURLConnection;
import java.net.URL;
import java.net.URLConnection;


public class HttpUrlConnectionTest {

    private static final Logger logger = LogManager.getLogger(HttpUrlConnectionTest.class);

    
    public static String doGet(String url) {
        HttpURLConnection urlConnection = null;
        try {
            // 新建URL对象
            URL urlObject = new URL(url);
            // 打开URL连接
            urlConnection = (HttpURLConnection) urlObject.openConnection();
            // 设置请求方法
            urlConnection.setRequestMethod(WebConstant.GET_METHOD);
            // 设置请求头内容类型和字符集类型
            urlConnection.setRequestProperty(WebConstant.CONTENT_TYPE, WebConstant.APPLICATION_JSON);
            // 不使用缓存
            urlConnection.setUseCaches(BooleanConstant.FALSE);
            // 设置连接超时时间，单位：毫秒
            urlConnection.setConnectTimeout(2000);
            // 设置读取数据超时时间，单位：毫秒
            urlConnection.setReadTimeout(2000);

            // 获取响应
            return inputStreamProcess(urlConnection);
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    
    public static String doPost(String url, String params) {
        HttpURLConnection urlConnection = null;
        try {
            // 新建URL对象
            URL urlObject = new URL(url);
            // 打开URL连接
            urlConnection = (HttpURLConnection) urlObject.openConnection();
            // 设置请求方法
            urlConnection.setRequestMethod(WebConstant.POST_METHOD);
            // 设置请求头内容类型和字符集类型
            urlConnection.setRequestProperty(WebConstant.CONTENT_TYPE, WebConstant.APPLICATION_JSON);
            urlConnection.setRequestProperty("accept", "*
    public static String responseProcess(URLConnection urlConnection, String params) {
        try (PrintWriter printWriter = new PrintWriter(urlConnection.getOutputStream())) {
            // 发送请求参数
            printWriter.print(params);
            // 刷新输出流
            printWriter.flush();
            return inputStreamProcess(urlConnection);
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    
    public static String inputStreamProcess(URLConnection urlConnection) {
        try (InputStream inputStream = urlConnection.getInputStream(); BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(inputStream))) {
            String line;
            StringBuilder response = new StringBuilder();
            while ((line = bufferedReader.readLine()) != null) {
                response.append(line);
            }
            return response.toString();
        } catch (Exception ex) {
            throw new RuntimeException(ex);
        }
    }

    public static void main(String[] args) {
        // GET：请求
        String getUrl = "http://localhost:9121/api/v1/mongodb/read?userId=0x001";
        String getResponse = doGet(getUrl);
        logger.info(">>>>>>>>>Get response:{}", getResponse);
        // POST：请求
        String postUrl = "http://localhost:9121/api/v1/mongodb/page";
        // 入参实体
        PageEntity pageEntity = new PageEntity(1, 2);
        Gson gson = new Gson();
        // 实体转JSON字符串
        String jsonString = gson.toJson(pageEntity);
        String postResponse = doPost(postUrl, jsonString);
        logger.info(">>>>>>>>>>Post response:{}", postResponse);
    }
}

HttpURLConnection发送POST请求：参数使用PrintWriter；POST参数传入时转换为JSON字符串；可配置请求方法、连接超时时间、读取超时时间。