java中讲讲URL的用法，举例？

4.URL类的实例

马克-to-win：URL（Uniform Resource Locator-----一致资源查找器）它用来指向Internet上的资源文件，比如 http://java.sun.com:8080/docs/introdiction.htm net包中的URL类提供API来访问Internet上的信息。

比如以上的URL中：

1）协议：http

2）IP 地址或主机名：java.sun.com

3）端口号：8080

4）实际文件路径：docs/introdiction.htm

例：2.4.1

/*no need to have network through to run the program.*/

import java.net.*;

import java.io.*;

public class TestMark_to_win {

    public static void main(String[] args) throws Exception {

        /* Class URL represents a Uniform Resource Locator, a pointer to a

         * "resource" on the World Wide Web. A resource can be something as

         * simple as a file or a directory, public URL(String spec)throws

         * MalformedURLException: Creates a URL object from the String

         * representation.

         */

        URL aURL = new URL("http://java.sun.com:8080/docs/books/"

                + "tutorial/index.html");

        System.out.println("protocol = " + aURL.getProtocol());

        System.out.println("host = " + aURL.getHost());

        System.out.println("filename = " + aURL.getFile());

        System.out.println("default port = " + aURL.getDefaultPort());

        System.out.println("port = " + aURL.getPort());

    }

}

例：2.4.2

/* This program needs an open connection to run.

*/

import java.net.*;

import java.io.*;

import java.util.*;

public class TestMark_to_win {

    public static void main(String[] args) throws Exception {

        URL yahoo = new URL("https://www.oracle.com/index.html");

        /* public URLConnection openConnection() throws IOException: Returns a

         * URLConnection object that represents a connection to the remote

         * object referred to by the URL.

         */

        URLConnection yahooConnection = yahoo.openConnection();

        /* public long getLastModified() Returns the value of the last-modified

         * header field. The result is the number of milliseconds since January

         * 1, 1970 GMT.

         */

        System.out.println("content LastModified"

                + new Date(yahooConnection.getLastModified()));

        /*public InputStream getInputStream()throws IOException: Returns an

         * input stream that reads from this open connection.

         */

        // DataInputStream in = new

        // DataInputStream(yahooConnection.getInputStream());

        BufferedReader in = new BufferedReader(new InputStreamReader(

                yahooConnection.getInputStream()));

        String inputLine;

        for (int i = 0; i < 25; i++) {

            inputLine = in.readLine();

            System.out.println(inputLine);

        }

        in.close();

    }

}

更多请见：https://blog.csdn.net/qq_44639795/article/details/102319021