Java 基础 (网络编程 UDP 例子, URL)

UDP

UDPTest.java

package com.klvchen.java1;

import org.junit.Test;

import java.io.IOException;
import java.net.*;

public class UDPTest {

    @Test
    public void sender() throws IOException {

        DatagramSocket socket = new DatagramSocket();

        String str = "我是UDP方式发送的导弹";
        byte[] data = str.getBytes();
        InetAddress inet = InetAddress.getLocalHost();
        DatagramPacket packet = new DatagramPacket(data, 0, data.length,inet,9090);

        socket.send(packet);

        socket.close();

    }

    @Test
    public void receiver() throws IOException{

        DatagramSocket socket = new DatagramSocket(9090);

        byte[] buffer = new byte[100];
        DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length);

        socket.receive(packet);

        System.out.println(new String(packet.getData(), 0, packet.getLength()));

        socket.close();
    }
}

URL

* URL(Uniform Resource Locator): 统一资源定位符，它表示 Internet 上某一资源的地址。
* 它是一种具体的URI，即URL可以用来标识一个资源，而且还指明了如何locate这个资源。
* 通过URL我们可以访问 Internet上的各种网络资源，比如最常见的 www，ftp站点。浏览器通过解析给定的URL可以在网络上查找相应的文件或其他资源。

* URL的基本结构由5部分组成:
<传输协议>://<主机名>:<端口号>/<文件名>#片段名?参数列表
例如：
http://192.168.1.100:8080/helloworld/index.jsp#a?username=shkstart&password=123

URLTest.java

package com.klvchen.java1;

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

public class URLTest {

    public static void main(String[] args){

        URL url = null;
        try {
            url = new URL("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fb-ssl.duitang.com%2Fuploads%2Fitem%2F201810%2F05%2F20181005142528_yinka.jpg&refer=http%3A%2F%2Fb-ssl.duitang.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1638864631&t=26377d1d4652702f21909f93fee1af0e");

            // 获取URL的协议名称
            System.out.println(url.getProtocol());
            // 获取该URL的主机名
            System.out.println(url.getHost());
            // 获取该URL的端口号
            System.out.println(url.getPort());
            //获取该URL的文件路径
            System.out.println(url.getPath());
            //获取该URL的文件名
            System.out.println(url.getFile());
            // 获取该URL的查询名
            System.out.println(url.getQuery());



        } catch (MalformedURLException e) {
            e.printStackTrace();
        }



    }
}

URLTest1.java

package com.klvchen.java1;

import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.net.HttpURLConnection;
import java.net.URL;

public class URLTest1 {

    public static void main(String[] args){

        HttpURLConnection urlConnection = null;
        InputStream is = null;
        FileOutputStream fos = null;
        try {
            URL url = new URL("https://gimg2.baidu.com/image_search/src=http%3A%2F%2Fb-ssl.duitang.com%2Fuploads%2Fitem%2F201810%2F05%2F20181005142528_yinka.jpg&refer=http%3A%2F%2Fb-ssl.duitang.com&app=2002&size=f9999,10000&q=a80&n=0&g=0n&fmt=jpeg?sec=1638864631&t=26377d1d4652702f21909f93fee1af0e");

            urlConnection = (HttpURLConnection) url.openConnection();

            urlConnection.connect();

            is = urlConnection.getInputStream();
            fos = new FileOutputStream("day10\\5.jpeg");

            byte[] buffer = new byte[1024];
            int len;
            while ((len = is.read(buffer)) != -1) {
                fos.write(buffer, 0, len);
            }

            System.out.println("下载完成");
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            if (is != null) {
                try {
                    is.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
            if (fos != null) {
                try {
                    fos.close();
                } catch (IOException e) {
                    e.printStackTrace();
                }

            }
            if (urlConnection != null) {
                urlConnection.disconnect();

            }
        }

    }
}