What is a URL? And URL class and urlconnection class
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Java
URL concept
protocol://resourceName
http://www.sun.com/ 协议名://主机名 http://localhost:8080/Test/admin/login.jsp 协议名://机器名:端口号/文件名
URL class
Urlconnection class
Example 1
package ch16; import java.io.IOException; import java.io.InputStream; import java.net.URL; import java.net.URLConnection; public class URLDemo { public static void main(String[] args) { try { URL url=new URL("http://www.baidu.com/"); System.out.println("协议:" + url.getProtocol()); System.out.println("主机:" + url.getHost()); System.out.println("端口:" + url.getPort()); InputStream in; } catch(IOException e) { //TODO 自动生成的 catch 块 e.printStackTrace(); } } }
URLConnection uc=url.openConnection(); in=uc.getInputStream(); byte[] b=new byte[1024]; int len; while((len=in.read(b))!=-1) { System.out.println(new String(b,len)); } in.close();
协议:http 主机:www.baidu.com 端口:-1 <!DOCTYPE html> <!--STATUS OK--><html> <head><Meta http-equiv=content-type content=text/html;charset=utf-8><Meta http-equiv=X-UA-Compatible content=IE=Edge><Meta content=always name=referrer><link rel=stylesheet type=text/css href=http://s1.bdstatic.com/r/www/cache/......<img src=//www.baidu.com/img/gs.gif> </p> </div> </div> </div> </body> </html>
Extract URL protocol name
package ch16; import java.net.MalformedURLException; import java.net.URL; import java.util.Scanner; public class URLDemo1 { public static void main(String[] args) { try { Scanner scan=new Scanner(system.in); //创建输入扫描器 System.out.println("请输入一个完整的网址:"); String line=scan.nextLine(); //获取用户输入文本 URL url=new URL(line); //创建URL对象 System.out.println("这个网址的主机名称是:"+url.getHost()); //获取主机名称 System.out.println("这个网址的URL协议名称是:"+url.getProtocol()); //获取协议名称 } catch(MalformedURLException e) { System.out.println("输入的是非法网址"); //提示错误信息 } } }
请输入一个完整的网址: http://www.baidu.com 这个网址的主机名称是:www.baidu.com 这个网址的URL协议名称是:http
请输入一个完整的网址: ftp://www.baidu.com/SEO 这个网址的主机名称是:www.baidu.com 这个网址的URL协议名称是:ftp
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