1. Netty 能做什么
1. http服务器 类 Tomcat ，但是没有实现web规范
2. socket 开发 rpc通信
3. 长链接的开发
2. netty的http程序示例
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| public class TestServer {
public static void main(String[] args) throws Exception{
//工作线程
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
//服务启动器
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new TestServerInitializer());
//绑定端口
ChannelFuture sync = bootstrap.bind(8899).sync();
sync.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
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| public class TestServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
//管道可以拥有很多个handler，类似于拦截器
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast("httpServerCodec",new HttpServerCodec());
//自定义处理器
pipeline.addLast("testHttpServerHandler",new TestHttpServerHandler());
}
}
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| public class TestHttpServerHandler extends SimpleChannelInboundHandler<HttpObject> {
//类似于 msgReceived 方法 , //接收消息，返回响应
@Override
protected void channelRead0(ChannelHandlerContext ctx, HttpObject msg) throws Exception {
if (msg instanceof HttpRequest) {
//构造一个响应内容
ByteBuf content = Unpooled.copiedBuffer("hello", CharsetUtil.UTF_8);
//构造响应体
FullHttpResponse response = new DefaultFullHttpResponse(
HttpVersion.HTTP_1_1, HttpResponseStatus.OK,content
);
response.headers().add(HttpHeaderNames.CONTENT_TYPE,"text/plain");
response.headers().add(HttpHeaderNames.CONTENT_LENGTH,content.readableBytes());
//回写response
ctx.writeAndFlush(response);
}
}
}
|
使用：
浏览器 localhost：8899
curl localhost：8899
3. netty实现socket编程示例
3.1 SocketServer的实现
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| public class TestSocketServer {
public static void main(String[] args) throws Exception {
NioEventLoopGroup bossGroup = new NioEventLoopGroup();
NioEventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap bootstrap = new ServerBootstrap();
bootstrap.group(bossGroup,workerGroup)
.channel(NioServerSocketChannel.class)
.childHandler(new TestSocketServerInitializer());
ChannelFuture sync = bootstrap.bind(8899).sync();
sync.channel().closeFuture().sync();
} finally {
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
public class TestSocketServerInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new LengthFieldBasedFrameDecoder(
Integer.MAX_VALUE,0,4,0,4));
pipeline.addLast(new LengthFieldPrepender(4));
pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast(new TestSocketServerHandler());
}
}
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
SocketAddress socketAddress = ctx.channel().remoteAddress();
System.out.println(socketAddress + " : " + msg );
ctx.writeAndFlush("write from server : " + UUID.randomUUID());
}
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3.2 SocketClient的实现
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| public class MySocketClient {
public static void main(String[] args) throws Exception {
NioEventLoopGroup loop = new NioEventLoopGroup();
try {
Bootstrap bootstrap = new Bootstrap();
bootstrap.group(loop)
.channel(NioSocketChannel.class)
.handler(new MySocketClientInitializer());
ChannelFuture future = bootstrap.connect("localhost", 8899).sync();
future.channel().closeFuture().sync();
} finally {
loop.shutdownGracefully();
}
}
}
public class MySocketClientInitializer extends ChannelInitializer<SocketChannel> {
@Override
protected void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline pipeline = ch.pipeline();
pipeline.addLast(new LengthFieldBasedFrameDecoder(
Integer.MAX_VALUE,0,4,0,4));
pipeline.addLast(new LengthFieldPrepender(4));
pipeline.addLast(new StringEncoder(CharsetUtil.UTF_8));
pipeline.addLast(new StringDecoder(CharsetUtil.UTF_8));
pipeline.addLast(new MySocketClientHandler());
}
}
class MySocketClientHandler extends SimpleChannelInboundHandler<String> {
@Override
protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception {
System.out.println(ctx.channel().remoteAddress() + " : " + msg);
ctx.writeAndFlush("from client : " + LocalDateTime.now());
}
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
super.channelActive(ctx);
ctx.writeAndFlush("sss");
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
// super.exceptionCaught(ctx, cause);
cause.printStackTrace();
ctx.close();
}
}
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分别启动服务端和客户端就可以在命令行看到输出
4. netty编程流程总结
在Netty中，几乎所有的代码编写流程都遵循以下流程
服务端：
1. 构建 ServerBootstrap
创建工作线程 NioEventLoopGroup
指定channel NioServerSocketChannel
指定handler
2. 构建ChannelInitializer
获取ChannelPipeline 添加netty处理器
添加自定义处理器
3. 编写自定义处理器
继承SimpleChannelInboundHandler 接收参数
然后通过ChannelHandlerContext写会数据
socket客户端：
1. 构建 Bootstrap
创建工作线程 NioEventLoopGroup
指定channel NioSocketChannel
指定handler
2. 构建ChannelInitializer
获取ChannelPipeline 添加netty处理器
添加自定义处理器
3. 编写自定义处理器
继承SimpleChannelInboundHandler 接收参数
然后通过ChannelHandlerContext写会数据
