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UDP网络通信

代码示例：

流 程：

• 1.DatagramSocket与DatagramPacket
• 2.建立发送端，接收端
• 3.建立数据包
• 4.调用Socket的发送、接收方法
• 5.关闭Socket
  发送端与接收端是两个独立的运行程序
  */

public class UDPTest {
       //发送端    @Test    public void sender(){
           DatagramSocket socket = null;        try {
               socket = new DatagramSocket();//  public DatagramPacket(byte[] buf,int length,InetAddress address,int port)构造数据报包，//   用来将长度为 length 的包发送到指定主机上的指定端口号。length 参数必须小于等于 buf.length            String str = "我是UDP方式发送的导弹";            byte[] buffer = str.getBytes();            InetAddress inet = InetAddress.getLocalHost();            DatagramPacket packet = new DatagramPacket(buffer,0,buffer.length,inet,7788);            socket.send(packet);            System.out.println("发送成功！");        } catch (IOException e) {
               e.printStackTrace();        } finally {
               if(socket != null){
                   socket.close();            }        }    }    //接收端    @Test    public void receiver(){
           DatagramSocket socket = null;        try {
               socket = new DatagramSocket(7788);            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()));        } catch (IOException e) {
               e.printStackTrace();        } finally {
               if(socket != null){
                   socket.close();            }        }    }}

URL编程

1.URL(Uniform Resource Locator)的理解:

• URL网络编程
• 1.URL:统一资源定位符，对应着互联网的某一资源地址
  

2.URL的5个基本结构：

• 2.格式：
• http://localhost:8080/examples/beauty.jpg?username=Tom
• 协议 主机名 端口号 资源地址 参数列表
• 

3.如何实例化:

URL url = new URL("“http://localhost:8080/examples/beauty.jpg?username=Tom”");

4.常用方法：

5.可以读取、下载对应的url资源：

public class URLTest1 {
       public static void main(String[] args) {
           HttpURLConnection urlConnection = null;        InputStream is = null;        FileOutputStream fos = null;        try {
               URL url = new URL("http://localhost:8080/examples/beauty.jpg");            urlConnection = (HttpURLConnection) url.openConnection();            urlConnection.connect();            is = urlConnection.getInputStream();            fos = new FileOutputStream("day10\\beauty3.jpg");            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 {
               //关闭资源            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();            }        }    }}

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