本文详细介绍Netty的实现原理及高级应用技巧，包括通信步骤、丢弃服务实现、粘包拆包解决方案、序列化技术及长连接管理等核心内容。
Netty 实现通信的步骤：
1.创建两个NIO线程组，一个专门用于网络事件处理（接受客户端的连接），另一个则进行网络通信读写。
2.创建一个ServerBootstrap对象，配置Netty的一系列参数，例如接受传出数据的缓存大小等。
3.创建一个实际处理数据的类Channellnitalizer，进行初始化的准备工作，比如设置接受传出数据的字符 格式 以及实际处理数据的接口
4.绑定接口，执行同步阻塞方法等待服务器启动即可。
如此简单的四个步骤，我们的服务器端就编写完成了，几十行代码 就可以把之前NIO的代码代替。
DISCARD服务(丢弃服务，指的是会忽略所有接收的数据的一种协议)
世界上最简单的协议不是”Hello,World!”，是DISCARD，他是一种丢弃了所有接受到的数据，并不做有任何的响应的协议。
为了实现DISCARD协议，你唯一需要做的就是忽略所有收到的数据。让我们从处理器的实现开始，处理器是由Netty生成用来处理I/O事件的。
01 | package io.netty.example.discard; |
02 |
03 | import io.netty.buffer.ByteBuf; |
04 |
05 | import io.netty.channel.ChannelHandlerContext; |
06 | import io.netty.channel.ChannelHandlerAdapter; |
07 |
08 | /** |
09 | * Handles a server-side channel. |
10 | */ |
11 | public class DiscardServerHandler extends ChannelHandlerAdapter { // (1) |
12 |
13 | @Override |
14 | public void channelRead(ChannelHandlerContext ctx, Object msg) { // (2) |
15 | // Discard the received data silently. |
16 | ((ByteBuf) msg).release(); // (3) |
17 | } |
18 |
19 | @Override |
20 | public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) { // (4) |
21 | // Close the connection when an exception is raised. |
22 | cause.printStackTrace(); |
23 | ctx.close(); |
24 | } |
25 | } |
- DisCardServerHandler 继承自 ChannelHandlerAdapter，这个类实现了ChannelHandler接口，ChannelHandler提供了许多事件处理的接口方法，然后你可以覆盖这些方法。现在仅仅只需要继承ChannelHandlerAdapter类而不是你自己去实现接口方法。
- 这里我们覆盖了chanelRead()事件处理方法。每当从客户端收到新的数据时，这个方法会在收到消息时被调用，这个例子中，收到的消息的类型是ByteBuf
- 为了实现DISCARD协议，处理器不得不忽略所有接受到的消息。ByteBuf是一个引用计数对象，这个对象必须显示地调用release()方法来释放。请记住处理器的职责是释放所有传递到处理器的引用计数对象。通常，channelRead()方法的实现就像下面的这段代码：
1@Override2publicvoidchannelRead(ChannelHandlerContext ctx, Object msg) {3try{4// Do something with msg5}finally{6ReferenceCountUtil.release(msg);7}8} - exceptionCaught()事件处理方法是当出现Throwable对象才会被调用，即当Netty由于IO错误或者处理器在处理事件时抛出的异常时。在大部分情况下，捕获的异常应该被记录下来并且把关联的channel给关闭掉。然而这个方法的处理方式会在遇到不同异常的情况下有不同的实现，比如你可能想在关闭连接之前发送一个错误码的响应消息。
public class Server {
public static void main(String[] args) throws Exception {
//1 第一个线程组 是用于接收Client端连接的
EventLoopGroup bossGroup = new NioEventLoopGroup();
//2 第二个线程组 是用于实际的业务处理操作的
EventLoopGroup workerGroup = new NioEventLoopGroup();
//3 创建一个辅助类Bootstrap，就是对我们的Server进行一系列的配置
ServerBootstrap b = new ServerBootstrap();
//把俩个工作线程组加入进来
b.group(bossGroup, workerGroup)
//我要指定使用NioServerSocketChannel这种类型的通道
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024) //设置tcp列队缓冲区
.option(ChannelOption.SO_SNDBUF, 32*1024) //设置发送缓冲大小
.option(ChannelOption.SO_RCVBUF, 32*1024) //这是接收缓冲大小
.option(ChannelOption.SO_KEEPALIVE, true) //保持连接
//一定要使用 childHandler 去绑定具体的 事件处理器
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(new ServerHandler());
}
});
//绑定指定的端口 进行监听
ChannelFuture f = b.bind(8765).sync();
//Thread.sleep(1000000);
f.channel().closeFuture().sync();
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
package bhz.netty.helloworld;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFutureListener;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class ServerHandler extends ChannelHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("server channel active... ");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg)
throws Exception {
ByteBuf buf = (ByteBuf) msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body = new String(req, "utf-8");
System.out.println("Server :" + body );
String response = "进行返回给客户端的响应：" + body ;
ctx.writeAndFlush(Unpooled.copiedBuffer(response.getBytes()));
//.addListener(ChannelFutureListener.CLOSE);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx)
throws Exception {
System.out.println("读完了");
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable t)
throws Exception {
ctx.close();
}
}
package bhz.netty.helloworld;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
public class Client {
public static void main(String[] args) throws Exception{
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture cf1 = b.connect("127.0.0.1", 8765).sync();
//ChannelFuture cf2 = b.connect("127.0.0.1", 8764).sync();
//发送消息
Thread.sleep(1000);
cf1.channel().writeAndFlush(Unpooled.copiedBuffer("777".getBytes()));
cf1.channel().writeAndFlush(Unpooled.copiedBuffer("666".getBytes()));
//cf2.channel().writeAndFlush(Unpooled.copiedBuffer("888".getBytes()));
Thread.sleep(2000);
cf1.channel().writeAndFlush(Unpooled.copiedBuffer("888".getBytes()));
//cf2.channel().writeAndFlush(Unpooled.copiedBuffer("666".getBytes()));
cf1.channel().closeFuture().sync();
//cf2.channel().closeFuture().sync();
group.shutdownGracefully();
}
}
package bhz.netty.helloworld;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelPromise;
import io.netty.util.ReferenceCountUtil;
public class ClientHandler extends ChannelHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
ByteBuf buf = (ByteBuf) msg;
byte[] req = new byte[buf.readableBytes()];
buf.readBytes(req);
String body = new String(req, "utf-8");
System.out.println("Client :" + body );
String response = "收到服务器端的返回信息：" + body;
} finally {
ReferenceCountUtil.release(msg);
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause)
throws Exception {
ctx.close();
}
}
- NioEventLoopGroup 是用来处理I/O操作的多线程事件循环器，Netty提供了许多不同的EventLoopGroup的实现用来处理不同传输协议。在这个例子中我们实现了一个服务端的应用，因此会有2个NioEventLoopGroup会被使用。第一个经常被叫做‘boss’，用来接收进来的连接。第二个经常被叫做‘worker’，用来处理已经被接收的连接，一旦‘boss’接收到连接，就会把连接信息注册到‘worker’上。如何知道多少个线程已经被使用，如何映射到已经创建的Channels上都需要依赖于EventLoopGroup的实现，并且可以通过构造函数来配置他们的关系。
- ServerBootstrap 是一个启动NIO服务的辅助启动类。你可以在这个服务中直接使用Channel，但是这会是一个复杂的处理过程，在很多情况下你并不需要这样做。
- 这里我们指定使用NioServerSocketChannel类来举例说明一个新的Channel如何接收进来的连接。
- 这里的事件处理类经常会被用来处理一个最近的已经接收的Channel。ChannelInitializer是一个特殊的处理类，他的目的是帮助使用者配置一个新的Channel。也许你想通过增加一些处理类比如DiscardServerHandle来配置一个新的Channel或者其对应的ChannelPipeline来实现你的网络程序。当你的程序变的复杂时，可能你会增加更多的处理类到pipline上，然后提取这些匿名类到最顶层的类上。
- 你可以设置这里指定的通道实现的配置参数。我们正在写一个TCP/IP的服务端，因此我们被允许设置socket的参数选项比如tcpNoDelay和keepAlive。请参考ChannelOption和详细的ChannelConfig实现的接口文档以此可以对ChannelOptions的有一个大概的认识。
- 你关注过option()和childOption()吗？option()是提供给NioServerSocketChannel用来接收进来的连接。childOption()是提供给由父管道ServerChannel接收到的连接，在这个例子中也是NioServerSocketChannel。
- 我们继续，剩下的就是绑定端口然后启动服务。这里我们在机器上绑定了机器所有网卡上的8765端口。当然现在你可以多次调用bind()方法(基于不同绑定地址)。
9. ctx.write(Object)方法不会使消息写入到通道上，他被缓冲在了内部，你需要调用ctx.flush()方法来把缓冲区中数据强行输出。或者你可以用更简洁的cxt.writeAndFlush(msg)以达到同样的目的。
TCP拆包和粘包问题的解决：
1.消息定长，例如每个报文的大小固定为200个字节，如果不够，空位补空格。
2.在包尾部增加特殊字符进行分割，例如加回车
3.消息分为消息头和消息体，在消息头中包含表示消息总长度的字段，然后进行业务逻辑的处理。（类似于自定协议）
Netty如何去解决粘包问题
1.分隔符类DellmlterBasedFrameDecoder(自定义分隔符)
package bhz.netty.ende1;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
public class Server {
public static void main(String[] args) throws Exception{
//1 创建2个线程，一个是负责接收客户端的连接。一个是负责进行数据传输的
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
//2 创建服务器辅助类
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
.option(ChannelOption.SO_SNDBUF, 32*1024)
.option(ChannelOption.SO_RCVBUF, 32*1024)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
//设置特殊分隔符
ByteBuf buf = Unpooled.copiedBuffer("$_".getBytes());
sc.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, buf));
//设置字符串形式的解码
sc.pipeline().addLast(new StringDecoder()); //转换成String 类型
sc.pipeline().addLast(new ServerHandler());
}
});
//4 绑定连接
ChannelFuture cf = b.bind(8765).sync();
//等待服务器监听端口关闭
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
package bhz.netty.ende1;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class ServerHandler extends ChannelHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(" server channel active... ");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
String request = (String)msg;
System.out.println("Server :" + request);
String response = "服务器响应：" + msg + "$_";
ctx.writeAndFlush(Unpooled.copiedBuffer(response.getBytes()));
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable t) throws Exception {
ctx.close();
}
}
package bhz.netty.ende1;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
public class Client {
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
//
ByteBuf buf = Unpooled.copiedBuffer("$_".getBytes());
sc.pipeline().addLast(new DelimiterBasedFrameDecoder(1024, buf));
sc.pipeline().addLast(new StringDecoder());
sc.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
cf.channel().writeAndFlush(Unpooled.copiedBuffer("bbbb$_".getBytes()));
cf.channel().writeAndFlush(Unpooled.copiedBuffer("cccc$_".getBytes()));
//等待客户端端口关闭
cf.channel().closeFuture().sync();
group.shutdownGracefully();
}
}
package bhz.netty.ende1;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
public class ClientHandler extends ChannelHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println("client channel active... ");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
String response = (String)msg;
System.out.println("Client: " + response);
} finally {
ReferenceCountUtil.release(msg);
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
2.FixedLengthFrameDecode(定长)
package bhz.netty.ende2;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
public class Server {
public static void main(String[] args) throws Exception{
//1 创建2个线程，一个是负责接收客户端的连接。一个是负责进行数据传输的
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
//2 创建服务器辅助类
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
.option(ChannelOption.SO_SNDBUF, 32*1024)
.option(ChannelOption.SO_RCVBUF, 32*1024)
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
//设置定长字符串接收
sc.pipeline().addLast(new FixedLengthFrameDecoder(5));
//设置字符串形式的解码
sc.pipeline().addLast(new StringDecoder());
sc.pipeline().addLast(new ServerHandler());
}
});
//4 绑定连接
ChannelFuture cf = b.bind(8765).sync();
//等待服务器监听端口关闭
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
package bhz.netty.ende2;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
public class ServerHandler extends ChannelHandlerAdapter {
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
System.out.println(" server channel active... ");
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
String request = (String)msg;
System.out.println("Server :" + msg);
String response = request ;
ctx.writeAndFlush(Unpooled.copiedBuffer(response.getBytes()));
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable t) throws Exception {
}
}
package bhz.netty.ende2;
import io.netty.bootstrap.Bootstrap;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.codec.DelimiterBasedFrameDecoder;
import io.netty.handler.codec.FixedLengthFrameDecoder;
import io.netty.handler.codec.string.StringDecoder;
import io.netty.handler.codec.string.StringEncoder;
public class Client {
public static void main(String[] args) throws Exception {
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(new FixedLengthFrameDecoder(5));
sc.pipeline().addLast(new StringDecoder());
sc.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
cf.channel().writeAndFlush(Unpooled.wrappedBuffer("aaaaabbbbb".getBytes()));
cf.channel().writeAndFlush(Unpooled.copiedBuffer("ccccccc ".getBytes()));
//等待客户端端口关闭
cf.channel().closeFuture().sync();
group.shutdownGracefully();
}
}
package bhz.netty.ende2;
package bhz.netty.serial;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
public class Server {
public static void main(String[] args) throws Exception{
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
//设置日志
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel sc) throws Exception {
// Jboss Marshalling 序列号
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ServerHandler());
}
});
ChannelFuture cf = b.bind(8765).sync();
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
import io.netty.channel.ChannelHandlerAdapter;import io.netty.channel.ChannelHandlerContext;
public class ClientHandler extends ChannelHandlerAdapter{@Overridepublic void channelActive(ChannelHandlerContext ctx) throws Exception {System.out.println("client channel active... ");}@Overridepublic void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {String response = (String)msg;System.out.println("Client: " + response);}@Overridepublic void channelReadComplete(ChannelHandlerContext ctx) throws Exception {}@Overridepublic void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {}}
Netty编解码技术：
编解码技术，说白了就是JAVA序列化技术，序列化目的就是 一个进行网络传输，二是对象持久化
虽然我们可以使用JAVA进行对象序列化，Netty去传输，但是java 序列化的硬伤太多，比如JAVA序列化无法跨语言，序列化后码流太大，序列化性能太低等等
主流的编解码框架：
JOBSS masrshalling
google的protobuf
基于protobuf的kyro
MessagePack框架
JOBSS masrshalling 是一个java对象序列化包，对JDK默认的序列化框架进行了优化，但又保持跟java.io.Seriallzable的接口的兼容，同时增加了一些可调的参数和附加特性
package bhz.netty.serial;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
public class Server {
public static void main(String[] args) throws Exception{
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
//设置日志
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel sc) throws Exception {
// Jboss Marshalling 序列号
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ServerHandler());
}
});
ChannelFuture cf = b.bind(8765).sync();
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
package bhz.netty.serial;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import java.io.File;
import java.io.FileOutputStream;
import bhz.utils.GzipUtils;
public class ServerHandler extends ChannelHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
Req req = (Req)msg;
System.out.println("Server : " + req.getId() + ", " + req.getName() + ", " + req.getRequestMessage());
byte[] attachment = GzipUtils.ungzip(req.getAttachment());
String path = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar + "001.jpg";
FileOutputStream fos = new FileOutputStream(path);
fos.write(attachment);
fos.close();
Resp resp = new Resp();
resp.setId(req.getId());
resp.setName("resp" + req.getId());
resp.setResponseMessage("响应内容" + req.getId());
ctx.writeAndFlush(resp);//.addListener(ChannelFutureListener.CLOSE);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
package bhz.netty.serial;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import java.io.File;
import java.io.FileInputStream;
import bhz.utils.GzipUtils;
public class Client {
public static void main(String[] args) throws Exception{
EventLoopGroup group = new NioEventLoopGroup();
Bootstrap b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
// Jboss Marshalling 序列号
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ClientHandler());
}
});
ChannelFuture cf = b.connect("127.0.0.1", 8765).sync();
for(int i = 0; i < 5; i++ ){
Req req = new Req();
req.setId("" + i);
req.setName("pro" + i);
req.setRequestMessage("数据信息" + i);
String path = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar + "001.jpg";
File file = new File(path);
FileInputStream in = new FileInputStream(file);
byte[] data = new byte[in.available()];
in.read(data);
in.close();
req.setAttachment(GzipUtils.gzip(data));
cf.channel().writeAndFlush(req);
}
cf.channel().closeFuture().sync();
group.shutdownGracefully();
}
}
package bhz.netty.serial;
import io.netty.channel.ChannelHandlerAdapter;
import io.netty.channel.ChannelHandlerContext;
import io.netty.util.ReferenceCountUtil;
public class ClientHandler extends ChannelHandlerAdapter{
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
try {
Resp resp = (Resp)msg;
System.out.println("Client : " + resp.getId() + ", " + resp.getName() + ", " + resp.getResponseMessage());
} finally {
ReferenceCountUtil.release(msg);
}
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
ctx.close();
}
}
package bhz.netty.serial;
import io.netty.handler.codec.marshalling.DefaultMarshallerProvider;
import io.netty.handler.codec.marshalling.DefaultUnmarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallerProvider;
import io.netty.handler.codec.marshalling.MarshallingDecoder;
import io.netty.handler.codec.marshalling.MarshallingEncoder;
import io.netty.handler.codec.marshalling.UnmarshallerProvider;
import org.jboss.marshalling.MarshallerFactory;
import org.jboss.marshalling.Marshalling;
import org.jboss.marshalling.MarshallingConfiguration;
/**
* Marshalling工厂
* @author（alienware）
* @since 2014-12-16
*/
public final class MarshallingCodeCFactory {
/**
* 创建Jboss Marshalling解码器MarshallingDecoder
* @return MarshallingDecoder
*/
public static MarshallingDecoder buildMarshallingDecoder() {
//首先通过Marshalling工具类的精通方法获取Marshalling实例对象 参数serial标识创建的是java序列化工厂对象。
final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
//创建了MarshallingConfiguration对象，配置了版本号为5
final MarshallingConfiguration configuration = new MarshallingConfiguration();
configuration.setVersion(5);
//根据marshallerFactory和configuration创建provider
UnmarshallerProvider provider = new DefaultUnmarshallerProvider(marshallerFactory, configuration);
//构建Netty的MarshallingDecoder对象，俩个参数分别为provider和单个消息序列化后的最大长度
MarshallingDecoder decoder = new MarshallingDecoder(provider, 1024 * 1024 * 1);
return decoder;
}
/**
* 创建Jboss Marshalling编码器MarshallingEncoder
* @return MarshallingEncoder
*/
public static MarshallingEncoder buildMarshallingEncoder() {
final MarshallerFactory marshallerFactory = Marshalling.getProvidedMarshallerFactory("serial");
final MarshallingConfiguration configuration = new MarshallingConfiguration();
configuration.setVersion(5);
MarshallerProvider provider = new DefaultMarshallerProvider(marshallerFactory, configuration);
//构建Netty的MarshallingEncoder对象，MarshallingEncoder用于实现序列化接口的POJO对象序列化为二进制数组
MarshallingEncoder encoder = new MarshallingEncoder(provider);
return encoder;
}
}
package bhz.netty.serial;
import java.io.Serializable;
public class Req implements Serializable{
private static final long SerialVersionUID = 1L;
private String id ;
private String name ;
private String requestMessage ;
private byte[] attachment;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getRequestMessage() {
return requestMessage;
}
public void setRequestMessage(String requestMessage) {
this.requestMessage = requestMessage;
}
public byte[] getAttachment() {
return attachment;
}
public void setAttachment(byte[] attachment) {
this.attachment = attachment;
}
}
package bhz.netty.serial;
import java.io.Serializable;
public class Resp implements Serializable{
private static final long serialVersionUID = 1L;
private String id;
private String name;
private String responseMessage;
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getResponseMessage() {
return responseMessage;
}
public void setResponseMessage(String responseMessage) {
this.responseMessage = responseMessage;
}
}
package bhz.utils;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
public class GzipUtils {
public static byte[] gzip(byte[] data) throws Exception{
ByteArrayOutputStream bos = new ByteArrayOutputStream();
GZIPOutputStream gzip = new GZIPOutputStream(bos);
gzip.write(data);
gzip.finish();
gzip.close();
byte[] ret = bos.toByteArray();
bos.close();
return ret;
}
public static byte[] ungzip(byte[] data) throws Exception{
ByteArrayInputStream bis = new ByteArrayInputStream(data);
GZIPInputStream gzip = new GZIPInputStream(bis);
byte[] buf = new byte[1024];
int num = -1;
ByteArrayOutputStream bos = new ByteArrayOutputStream();
while((num = gzip.read(buf, 0 , buf.length)) != -1 ){
bos.write(buf, 0, num);
}
gzip.close();
bis.close();
byte[] ret = bos.toByteArray();
bos.flush();
bos.close();
return ret;
}
public static void main(String[] args) throws Exception{
//读取文件
String readPath = System.getProperty("user.dir") + File.separatorChar + "sources" + File.separatorChar + "006.jpg";
File file = new File(readPath);
FileInputStream in = new FileInputStream(file);
byte[] data = new byte[in.available()];
in.read(data);
in.close();
System.out.println("文件原始大小:" + data.length);
//测试压缩
byte[] ret1 = GzipUtils.gzip(data);
System.out.println("压缩之后大小:" + ret1.length);
byte[] ret2 = GzipUtils.ungzip(ret1);
System.out.println("还原之后大小:" + ret2.length);
//写出文件
String writePath = System.getProperty("user.dir") + File.separatorChar + "receive" + File.separatorChar + "006.jpg";
FileOutputStream fos = new FileOutputStream(writePath);
fos.write(ret2);
fos.close();
}
}
实践实际场景一、数据通信
1.使用长连接通道不断开进行通信，也就是服务器和客户端一直处于开启状态，如果服务器性能比较好，并且我们的客户端数量比较少的情况下。
2.一次性批量提交数据，采用短连接方式，也就是我们会把数据保存在本地临时缓存，当达到临界值时进行一次性批量提交，这种做不到实时性传输。
3.我们可以使用一种特殊的长连接，在指定某一时间内，服务器端与客户端没有任何通信，则断开连接，下次连接则是客户端想服务器发送请求的时候，再次建立连接，但是这种模式 我们要需要考虑2个因素：
（1）如何在超时后关闭通道，关闭后我们又如何再次建立连接？（Netty5 之后提供）
（2）客户端宕机时，我们无需考虑，下次客户端重启之后我们就可以与服务器建立连接，但是服务器宕机时，我们的客户端如何与服务器进行连接呢？（Netty5 之后提供）
package bhz.netty.runtime;
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.ChannelOption;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioServerSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.ReadTimeoutHandler;
public class Server {
public static void main(String[] args) throws Exception{
EventLoopGroup pGroup = new NioEventLoopGroup();
EventLoopGroup cGroup = new NioEventLoopGroup();
ServerBootstrap b = new ServerBootstrap();
b.group(pGroup, cGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 1024)
//设置日志
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
sc.pipeline().addLast(new ReadTimeoutHandler(5));
sc.pipeline().addLast(new ServerHandler());
}
});
ChannelFuture cf = b.bind(8765).sync();
cf.channel().closeFuture().sync();
pGroup.shutdownGracefully();
cGroup.shutdownGracefully();
}
}
package bhz.netty.runtime;
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelInitializer;
import io.netty.channel.EventLoopGroup;
import io.netty.channel.nio.NioEventLoopGroup;
import io.netty.channel.socket.SocketChannel;
import io.netty.channel.socket.nio.NioSocketChannel;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.timeout.ReadTimeoutHandler;
import java.util.concurrent.TimeUnit;
/**
* Best Do It
*/
public class Client {
private static class SingletonHolder {
static final Client instance = new Client();
}
public static Client getInstance(){
return SingletonHolder.instance;
}
private EventLoopGroup group;
private Bootstrap b;
private ChannelFuture cf ;
private Client(){
group = new NioEventLoopGroup();
b = new Bootstrap();
b.group(group)
.channel(NioSocketChannel.class)
.handler(new LoggingHandler(LogLevel.INFO))
.handler(new ChannelInitializer<SocketChannel>() {
@Override
protected void initChannel(SocketChannel sc) throws Exception {
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingDecoder());
sc.pipeline().addLast(MarshallingCodeCFactory.buildMarshallingEncoder());
//超时handler（当服务器端与客户端在指定时间以上没有任何进行通信，则会关闭响应的通道，主要为减小服务端资源占用）
sc.pipeline().addLast(new ReadTimeoutHandler(5));
sc.pipeline().addLast(new ClientHandler());
}
});
}
public void connect(){
try {
this.cf = b.connect("127.0.0.1", 8765).sync();
System.out.println("远程服务器已经连接, 可以进行数据交换..");
} catch (Exception e) {
e.printStackTrace();
}
}
public ChannelFuture getChannelFuture(){
if(this.cf == null){
this.connect();
}
if(!this.cf.channel().isActive()){
this.connect();
}
return this.cf;
}
public static void main(String[] args) throws Exception{
final Client c = Client.getInstance();
//c.connect();
ChannelFuture cf = c.getChannelFuture();
for(int i = 1; i <= 3; i++ ){
Request request = new Request();
request.setId("" + i);
request.setName("pro" + i);
request.setRequestMessage("数据信息" + i);
cf.channel().writeAndFlush(request);
TimeUnit.SECONDS.sleep(4);
}
cf.channel().closeFuture().sync();
new Thread(new Runnable() {
@Override
public void run() {
try {
System.out.println("进入子线程...");
//判断通道是否断开 是否重连
ChannelFuture cf = c.getChannelFuture();
System.out.println(cf.channel().isActive());
System.out.println(cf.channel().isOpen());
//再次发送数据
Request request = new Request();
request.setId("" + 4);
request.setName("pro" + 4);
request.setRequestMessage("数据信息" + 4);
cf.channel().writeAndFlush(request);
cf.channel().closeFuture().sync();
System.out.println("子线程结束.");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
}).start();
System.out.println("断开连接,主线程结束..");
}
}
远程服务器已经连接, 可以进行数据交换..
Client : 1, response1, 响应内容1
Client : 2, response2, 响应内容2
Client : 3, response3, 响应内容3
断开连接,主线程结束..
进入子线程...
远程服务器已经连接, 可以进行数据交换..
true
true
Client : 4, response4, 响应内容4
子线程结束.
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