网络编程

IP

abcd地址分类 0-255对半分
如何查看IP，查看java帮助文档 中该类。

端口

通信协议

ULR

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;
public class UrlDown {
    public static void main(String[] args) throws IOException {
        //1.下载地址
        URL url = new URL("https://m701.music.126.net/20210111112635/1d76165639698f6ac64f02860722014c/jdyyaac/obj/w5rDlsOJwrLDjj7CmsOj/5546003514/e409/aed6/f93a/e0f802f6dbe22026d98c0129ec474324.m4a");
        //2.连接这个资源HTTP
        HttpURLConnection  urlConnection = (HttpURLConnection)url.openConnection();
        //3.io流读取
        InputStream inputStream = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream("4.m4a");
        byte[] buffer = new byte[1024];
        int len;
        while ((len=inputStream.read(buffer))!=-1){
            fos.write(buffer,0,len);

        }
        //4.逐层关闭资源
        fos.close();
        inputStream.close();
        urlConnection.disconnect();
    }
}