URL

URL

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 www.baidu.com -> xxxx.xxxx.xxxx.xxxx

协议: //ip地址:端口/项目名/资源

package com.hua;

import java.net.MalformedURLException;
import java.net.URL;

public class URLDemo01 {
    public static void main(String[] args) throws Exception {
        URL url = new URL("http://localhost:8080/helloworld/index.jsp?username=kuangshen&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());//全路径
        System.out.println(url.getFile());//文件
        System.out.println(url.getQuery());//参数
    }

package com.hua;

import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.MalformedURLException;
import java.net.URL;
import java.net.URLConnection;

public class URLDown {
    public static void main(String[] args) throws Exception {
        //1、下载地址
        URL url = new URL("https://cambrian-images.cdn.bcebos.com/ca301075b8ec31caeffd466f09c53a21_1528724735774.jpeg");
        //2、连接到这个资源 HTTP
        HttpURLConnection urlConnection = (HttpURLConnection) url.openConnection();

        InputStream is = urlConnection.getInputStream();
        FileOutputStream fos = new FileOutputStream(new File("photo.png"));
        byte[] buffer = new byte[1024];
        int len;
        while((len=is.read(buffer))!=-1){
            fos.write(buffer,0,len);
        }
        fos.close();
        is.close();
    }
}