https://www.baidu.com/

统一资源定位符:定位资源的,定位互联网上的某一个资源

DNS 域名解析

协议://ip地址:端口/项目名/资源

package top.ltyzqhh.Net;

import java.net.URL;

public class URLDemo01 {
    public static void main(String[] args) throws Exception {
        URL url = new URL("<http://localhost:8080/helloword/index.jsp?username=ltyzqhh&password=123>");
        System.out.println(url.getProtocol());//协议
        System.out.println(url.getHost());//主机ip
        System.out.println(url.getPort());//端口
        System.out.println(url.getPath());//文件
        System.out.println(url.getFile());//全路径
        System.out.println(url.getQuery());//参数
    }
}

网上下载

package top.ltyzqhh.Net;

import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class UrlDown {
    public static void main(String[] args) throws Exception {
        //1.下载地址
        //URL url = new URL("<https://www.ghibli.jp/gallery/howl049.jpg>");
        URL url = new URL("<https://m10.music.126.net/20210502230534/6f89e8ba5eb4ded1604d23e23ae54098/yyaac/obj/wonDkMOGw6XDiTHCmMOi/3228431698/05d9/8b56/c9c2/83b7f1f128e7f9597c7b3da8f4135913.m4a>");
        //2.连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();
        //3

        InputStream inputStream = urlConnection.getInputStream();

        FileOutputStream fos = new FileOutputStream("shall We Talk.m4a");

        byte[] buffer = new byte[1024];

        int len;

        while ((len=inputStream.read(buffer))!=-1)
        {
            fos.write(buffer,0,len);//写出这个数据
        }
        fos.close();
        inputStream.close();
        urlConnection.disconnect();//断开连接

    }
}