[网络协议]DatagramChannel用法

DatagramChannel用法

1.打开DatagramChannel

DatagramChannel server = DatagramChannel.open();
server.socket().bind(new InetSocketAddress(10086));

此例子是打开10086端口接收UDP接收包

2.接收数据

通过receive()接收UDP包

ByteBuffer receiveBuffer = ByteBuffer.allocate(64);
receiveBuffer.clear();
SocketAddress receiveAddr = server.receive(receiveBuffer);

SocketAddress可以获得发包的ip,端口等信息,用toString查看,格式如下/127.0.0.1:57126

3.发送数据

通过send()发送UDP包

DatagramChannel server = DatagramChannel.open();
ByteBuffer sendBuffer = ByteBuffer.wrap("client send".getBytes());
server.send(sendBuffer,new InetSocketAddress("127.0.0.1",10086));

4.连接

UDP不存在真正意义上的连接,这里的连接是向特定服务地址用write和read接收发送数据包

server.connect(new InetSocketAddress("127.0.0.1",10086));
int redSize = server.read(receiveBuffer);
server.write(sendBuffer);

read()和write()只有在connect()后才能使用,不然会抛NotYetConnectedException异常.用read()接收时,如果没有接收包,会抛PortUnreachableException

5.DatagramChannel示例

客户端发送,服务端接收的例子

package FileChannel演示;

import org.junit.Test;

import java.io.IOException;
import java.net.InetSocketAddress;
import java.net.SocketAddress;
import java.nio.ByteBuffer;
import java.nio.channels.DatagramChannel;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

public class DatagramChannelDemo {
    //发送的实现
    @Test
    public void sendDatagram() throws IOException, InterruptedException {
        //打开 DatagramChannel
        DatagramChannel sendChannel = DatagramChannel.open();
        InetSocketAddress sendAddress = new InetSocketAddress("127.0.0.1",9999);

        //发送
        while(true) {
            ByteBuffer buffer = ByteBuffer.wrap("你好,我是顾文韬".getBytes(StandardCharsets.UTF_8));
            sendChannel.send(buffer,sendAddress);
            System.out.println("已经发送完成");
            Thread.sleep(1000);
        }
    }
    //接收的实现
    @Test
    public void receiveDatagram() throws IOException {
        //打开 DatagramChannel
        DatagramChannel receiveChannel = DatagramChannel.open();
        InetSocketAddress sendAddress = new InetSocketAddress(9999);
        //绑定
        receiveChannel.bind(sendAddress);

        //buffer
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        //接收
        while(true) {
            buffer.clear();
            SocketAddress socketAddress = receiveChannel.receive(buffer);
            buffer.flip();
            System.out.println(socketAddress.toString());
            System.out.println(Charset.forName("UTF-8").decode(buffer));
        }
    }
   
}

//连接read和write
@Test
    public void testConnect() throws IOException {
        //打开DatagramChannel
        DatagramChannel connChannel = DatagramChannel.open();
        //绑定
        connChannel.bind(new InetSocketAddress(9999));
        //连接
        connChannel.connect(new InetSocketAddress("127.0.0.1",9999));
        //write方法
        connChannel.write(ByteBuffer.wrap("你好,我是顾文韬".getBytes(StandardCharsets.UTF_8)));
        //buffer
        ByteBuffer buffer = ByteBuffer.allocate(1024);

        while(true) {
            buffer.clear();
            connChannel.read(buffer);
            buffer.flip();
            System.out.println(Charset.forName("UTF-8").decode(buffer));
        }
    }