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NETTY使用

Netty Server端

导入Netty的库包

找到工程中的pom.xml文件,在dependencies中添加如下代码

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<dependency>
<groupId>io.netty</groupId>
<artifactId>netty-all</artifactId>
<version>4.1.48.Final</version>
</dependency>

创建NettyServer

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import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.ChannelPipeline;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;

public class NettyServer {
//绑定的端口号
private int port;

public NettyServer(int port) {
this.port = port;
bind();
}

private void bind() {
//创建线程组
EventLoopGroup boss = new NioEventLoopGroup();
EventLoopGroup worker = new NioEventLoopGroup();

try {
//定义服务端启动类
ServerBootstrap bootstrap = new ServerBootstrap();
//设置线程组
bootstrap.group(boss, worker);
//使用NioServerSocketChannel
bootstrap.channel(NioServerSocketChannel.class);
//位每个连接添加NettyServerHandler 处理器
bootstrap.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel)
throws Exception {
ChannelPipeline p = socketChannel.pipeline();
// 添加NettyServerHandler,用来处理Server端接收和处理消息的逻辑
p.addLast(new NettyServerHandler());
}
});
//绑定端口并进行阻塞
ChannelFuture channelFuture = bootstrap.bind(port).sync();
if (channelFuture.isSuccess()) {
System.err.println("启动Netty服务成功,端口号:" + this.port);
}
// 关闭连接之前一直阻塞
channelFuture.channel().closeFuture().sync();

} catch (Exception e) {
System.err.println("启动Netty服务异常,异常信息:" + e.getMessage());
e.printStackTrace();
} finally {
//退出的时候关闭线程组
boss.shutdownGracefully();
worker.shutdownGracefully();
}
}

public static void main(String[] args) throws InterruptedException {
//启动服务器
new NettyServer(10086);
}
}

创建NettyServerHandler

新建NettyServerHandler类,用来实现Server端接收和处理消息的逻辑

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import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandler;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import java.io.UnsupportedEncodingException;

//设置共享
@ChannelHandler.Sharable
public class NettyServerHandler extends ChannelInboundHandlerAdapter {

/**
* 读取数据
* @param ctx
* @param msg
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
//将msg强转成ByteBuf
ByteBuf buf = (ByteBuf) msg;
//从ByteBuf中获取消息
String recieved = getMessage(buf);
System.err.println("服务器接收到客户端消息:" + recieved);

try {
//使用ctx进行发送消息
ctx.writeAndFlush(getSendByteBuf("你好,客户端"));
System.err.println("服务器回复消息:你好,客户端");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
}
}

//客户端端连接
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
//super.channelActive(ctx);
System.out.println("一台客户端已经连接");
}

/*
* 从ByteBuf中获取信息 使用UTF-8编码返回
*/
private String getMessage(ByteBuf buf) {

byte[] con = new byte[buf.readableBytes()];
//将buf中的内容读取到con
buf.readBytes(con);
try {
return new String(con, "UTF8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return null;
}
}

@Override
public void channelInactive(ChannelHandlerContext ctx) throws Exception {
System.out.println("一个客户端的关闭了连接");
}

/**
* 发生异常
*
* @param ctx
* @param cause
* @throws Exception
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
System.out.println("发生了一个异常:" + cause.getMessage());
}

//发送消息
private ByteBuf getSendByteBuf(String message)
throws UnsupportedEncodingException {
//字符串转换成byte数组
byte[] req = message.getBytes("UTF-8");
//创建ByteBuf
ByteBuf pingMessage = Unpooled.buffer();
//向ByteBuf中写入消息
pingMessage.writeBytes(req);
//返回pingMessage
return pingMessage;
}
}

启动Server端

启动后打印信息

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启动Netty服务成功,端口号:10086

Netty Client端

导入Netty的库包

导入代码同上面的Server端代码

创建NettyClient

新建NettyClient类

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public class NettyClient {

/*
* 服务器端口号
*/
private int port;

/*
* 服务器IP
*/
private String host;

public NettyClient(int port, String host) throws InterruptedException {
this.port = port;
this.host = host;
start();
}

private void start() throws InterruptedException {
//创建线程组
EventLoopGroup eventLoopGroup = new NioEventLoopGroup();

try {
//定义客户端启动类
Bootstrap bootstrap = new Bootstrap();
//设置NioSocketChannel
bootstrap.channel(NioSocketChannel.class);
//设置线程组
bootstrap.group(eventLoopGroup);
//设置服务器的IP以及端口号
bootstrap.remoteAddress(host, port);
//设置处理类
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel socketChannel)
throws Exception {
//添加处理类
socketChannel.pipeline().addLast(new NettyClientHandler());
}
});
//连接到服务器并进行阻塞
ChannelFuture channelFuture = bootstrap.connect(host, port).sync();
if (channelFuture.isSuccess()) {
System.err.println("连接服务器成功");
}
//客户端关闭之前一直保持阻塞状态
channelFuture.channel().closeFuture().sync();
} finally {
//客户端关闭的时候关闭线程组
eventLoopGroup.shutdownGracefully();
}
}

public static void main(String[] args) throws InterruptedException {
new NettyClient(10086, "localhost");
}
}

创建NettyClientHandler

新建NettyClientHandler类,用来实现Server端接收和处理消息的逻辑

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import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;

import java.io.UnsupportedEncodingException;

public class NettyClientHandler extends ChannelInboundHandlerAdapter {

/**
* 连接到服务器触发
*
* @param ctx
* @throws Exception
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
byte[] data = "你好,服务器".getBytes();
ByteBuf firstMessage = Unpooled.buffer();
firstMessage.writeBytes(data);
ctx.writeAndFlush(firstMessage);
System.err.println("客户端发送消息:你好,服务器");
}

/**
* 读取数据
* @param ctx
* @param msg
* @throws Exception
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
ByteBuf buf = (ByteBuf) msg;
String rev = getMessage(buf);
System.err.println("客户端收到服务器消息:" + rev);
}


private String getMessage(ByteBuf buf) {
byte[] con = new byte[buf.readableBytes()];
buf.readBytes(con);
try {
return new String(con, "UTF8");
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
return null;
}
}
}

启动Client端

客户端输出
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连接服务器成功
客户端发送消息:你好,服务器
客户端收到服务器消息:你好,客户端
服务端输出
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启动Netty服务成功,端口号:10086
一台客户端已经连接
服务器接收到客户端消息:你好,服务器
服务器回复消息:你好,客户端

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