九、URL
统一资源定位符：定位资源，定位互谅网上的某一个资源
DNS：域名解析
协议://ip地址:端口号/项目名/对应的资源 可以多，但不可以少
查看网络连接的内容
package com.net; import java.net.URL; public class URLDemo01 { public static void main(String[] args) throws Exception { URL url = new URL("http://localhost:8080/hello/index.jsp?username=hxl"); 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 } }
下载资源
暂时先用tomcat来检验。运行下面代码需要tomcat启动
package com.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。这个地址必须是存在的 URL url = new URL("http://localhost:8080/hxl/securityFile.txt"); //2.连接到这个资源 HTTP HttpURLConnection urlConnection = (HttpURLConnection)url.openConnection(); InputStream inputStream = urlConnection.getInputStream(); //存储的文件 FileOutputStream fos = new FileOutputStream("securityFile.txt"); byte[] buffer = new byte[1024]; int len; while((len = inputStream.read(buffer)) != -1){ fos.write(buffer,0,len); } fos.close(); inputStream.close(); urlConnection.disconnect(); } }
