java 实现简单的http客户端

1、废话不多说，代码如下

package com.linhuaming.test;

import java.io.InputStream;
import java.io.OutputStream;
import java.net.MalformedURLException;
import java.net.Socket;
import java.net.URL;

/**
 * http客户端 测试
 */
public class HttpClientTest {

    public static void main(String[] args) throws Exception {
        try{
            // 请求地址、端口
            String httpURL = "http://127.0.0.1:8080/demo?username=lhm&password=123456";
            URL url = new URL(httpURL);
            String host = url.getHost();
            int port = url.getPort();

            // socket客户端
            Socket socket = new Socket(host,port);

            // 发送请求
            OutputStream outputStream = socket.getOutputStream();
            String req = createRequestHeader(url);
            outputStream.write(req.getBytes());
            outputStream.flush();
            System.out.println("------------------------请求结果-------------------------");
            System.out.println(req);
            Thread.sleep(2000);

            // 响应结果
            InputStream inputStream = socket.getInputStream();
            byte[] buffer = new byte[1024];
            int len = 0;
            StringBuilder ret = new StringBuilder();
            while ((len = inputStream.read(buffer)) >= 0) {
                ret.append(new String(buffer, 0, len));
            }
            System.out.println("------------------------响应结果-------------------------");
            System.out.println(ret);

            // 关闭流
            inputStream.close();
            outputStream.close();
            socket.close();
        }catch (Exception e){
            e.printStackTrace();
        }
    }

    /**
     * 创建请求头部
     * @param url
     * @return
     * @throws MalformedURLException
     */
    public static String createRequestHeader(URL url) throws MalformedURLException {
        StringBuilder sb = new StringBuilder();
        String path = "/";
        if (url.getPath() != null && url.getPath().length() > 0) {
            path = url.getPath();
        }
        String BR = "\r\n";
        sb.append("GET " + path + " HTTP/1.0" + BR);
        sb.append("HOST: " + url.getHost() + BR);
        sb.append("User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) " + BR);
        sb.append(BR);
        sb.append(url.getQuery());
        return sb.toString();
    }

}

2、运行结果，如下图所示