NIO流行框架 Netty

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： 查看源代码 打印 帮助 1 @Override 2 public void channelRead(ChannelHandlerContext ctx, Object msg) { 3     try { 4         // Do something with msg 5     } finally { 6         ReferenceCountUtil.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。 到目前为止一切都还比较顺利，我们已经实现了DISCARD服务的一半功能，剩下的需要编写一个main()方法来启动服务端的DiscardServerHandler。

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)。 8.  ChannelHandlerContext 对象提供了许多操作，使你能够触发各种各样的I/O事件和操作。这里我们调用了write(Object)方法来逐字地把接受到的消息写入。请注意不同于DISCARD的例子我们并没有释放接受到的消息，这是因为当写入的时候Netty已经帮我们释放了。

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.