Java学习笔记—开源框架Netty的简单使用
Java学习笔记—开源框架Netty的简单使用
1：什么是Netty
Netty是由JBOSS提供的一个java开源框架。Netty提供异步的、事件驱动的网络应用程序框架和工具，用以快速开发高性能、高可靠性的网络服务器和客户端程序。
Netty是一个基于NIO的客户，服务器端编程框架，使用Netty可以确保你快速和简单的开发出一个网络应用，例如实现了某种协议的客户，服务端应用。
Netty相当简化和流线化了网络应用的编程开发过程，例如，TCP和UDP的socket服务开发。
Netty是一个吸收了多种协议的实现经验，这些协议包括FTP,SMTP,HTTP，各种二进制，文本协议，并经过相当精心设计的项目，最终，Netty 成功的找到了一种方式，在保证易于开发的同时还保证了其应用的性能，稳定性和伸缩性。
官网地址：http://netty.io/index.html
2:Netty的特性
设计
统一的API，适用于不同的协议（阻塞和非阻塞）
基于灵活、可扩展的事件驱动模型
高度可定制的线程模型
可靠的无连接数据Socket支持（UDP）
性能
更好的吞吐量，低延迟
更省资源
尽量减少不必要的内存拷贝
安全
完整的SSL/TLS和STARTTLS的支持
能在Applet与Android的限制环境运行良好
健壮性
不再因过快、过慢或超负载连接导致OutOfMemoryError
不再有在高速网络环境下NIO读写频率不一致的问题
易用
完善的JavaDoc，用户指南和样例
简洁简单
3：Netty基本架构图
4：简单例子(本文中netty的版本是netty-all-4.0.29)
去官网下载jar http://netty.io/index.html 或者可以使用maven
io.netty netty-all 4.0.29.Final
以HTTP协议举例
service代码
package com.demo.http;
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.http.HttpRequestDecoder;
import io.netty.handler.codec.http.HttpResponseEncoder;
public class HttpServer {
public void start(int port) throws Exception {
EventLoopGroup bossGroup = new NioEventLoopGroup();
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup).channel(NioServerSocketChannel.class)
.childHandler(new ChannelInitializer() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
// server端发送的是httpResponse，所以要使用HttpResponseEncoder进行编码
ch.pipeline().addLast(new HttpResponseEncoder());
// server端接收到的是httpRequest，所以要使用HttpRequestDecoder进行解码
ch.pipeline().addLast(new HttpRequestDecoder());
ch.pipeline().addLast(new HttpServerInboundHandler());
}
}).option(ChannelOption.SO_BACKLOG, 128)
.childOption(ChannelOption.SO_KEEPALIVE, true);
ChannelFuture f = b.bind(port).sync();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
bossGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HttpServer server = new HttpServer();
System.out.println("Http Server listening on 8844 ...");
server.start(8844);
}
}
package com.demo.http;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONNECTION;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_LENGTH;
import static io.netty.handler.codec.http.HttpHeaders.Names.CONTENT_TYPE;
import static io.netty.handler.codec.http.HttpResponseStatus.OK;
import static io.netty.handler.codec.http.HttpVersion.HTTP_1_1;
import io.netty.buffer.ByteBuf;
import io.netty.buffer.Unpooled;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.DefaultFullHttpResponse;
import io.netty.handler.codec.http.FullHttpResponse;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpHeaders.Values;
import io.netty.handler.codec.http.HttpRequest;
public class HttpServerInboundHandler extends ChannelInboundHandlerAdapter {
private HttpRequest request;
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (msg instanceof HttpRequest) {
request = (HttpRequest) msg;
String uri = request.getUri();
System.out.println("Uri:" + uri);
}
if (msg instanceof HttpContent) {
HttpContent content = (HttpContent) msg;
ByteBuf buf = content.content();
System.out.println(buf.toString(io.netty.util.CharsetUtil.UTF_8));
buf.release();
String res = "www.ccblog.cn";
FullHttpResponse response = new DefaultFullHttpResponse(HTTP_1_1, OK,
Unpooled.wrappedBuffer(res.getBytes("UTF-8")));
response.headers().set(CONTENT_TYPE, "text/plain");
response.headers().set(CONTENT_LENGTH, response.content().readableBytes());
if (HttpHeaders.isKeepAlive(request)) {
response.headers().set(CONNECTION, Values.KEEP_ALIVE);
}
ctx.write(response);
ctx.flush();
}
}
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
System.out.println(cause.getMessage());
ctx.close();
}
}
客户端访问
第一中执行上面的main方法后 在浏览器里面直接输入
http://127.0.0.1:8844/ 你可以看到 www.ccblog.cn 内容。
第二种采用java编写客户端
代码如下
package com.demo.http;
import io.netty.bootstrap.Bootstrap;
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.NioSocketChannel;
import io.netty.handler.codec.http.DefaultFullHttpRequest;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpMethod;
import io.netty.handler.codec.http.HttpRequestEncoder;
import io.netty.handler.codec.http.HttpResponseDecoder;
import io.netty.handler.codec.http.HttpVersion;
import java.net.URI;
public class HttpClient {
public void connect(String host, int port) throws Exception {
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(workerGroup);
b.channel(NioSocketChannel.class);
b.option(ChannelOption.SO_KEEPALIVE, true);
b.handler(new ChannelInitializer() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
// 客户端接收到的是httpResponse响应，所以要使用HttpResponseDecoder进行解码
ch.pipeline().addLast(new HttpResponseDecoder());
// 客户端发送的是httprequest，所以要使用HttpRequestEncoder进行编码
ch.pipeline().addLast(new HttpRequestEncoder());
ch.pipeline().addLast(new HttpClientInboundHandler());
}
});
// Start the client.
ChannelFuture f = b.connect(host, port).sync();
URI uri = new URI("http://127.0.0.1:8844");
String msg = "Are you ok?";
DefaultFullHttpRequest request = new DefaultFullHttpRequest(HttpVersion.HTTP_1_1, HttpMethod.GET,
uri.toASCIIString(), Unpooled.wrappedBuffer(msg.getBytes("UTF-8")));
// 构建http请求
request.headers().set(HttpHeaders.Names.HOST, host);
request.headers().set(HttpHeaders.Names.CONNECTION, HttpHeaders.Values.KEEP_ALIVE);
request.headers().set(HttpHeaders.Names.CONTENT_LENGTH, request.content().readableBytes());
// 发送http请求
f.channel().write(request);
f.channel().flush();
f.channel().closeFuture().sync();
} finally {
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
HttpClient client = new HttpClient();
client.connect("127.0.0.1", 8844);
}
}
package com.demo.http;
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
import io.netty.handler.codec.http.HttpContent;
import io.netty.handler.codec.http.HttpHeaders;
import io.netty.handler.codec.http.HttpResponse;
public class HttpClientInboundHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
if (msg instanceof HttpResponse) {
HttpResponse response = (HttpResponse) msg;
System.out.println("CONTENT_TYPE:" + response.headers().get(HttpHeaders.Names.CONTENT_TYPE));
}
if (msg instanceof HttpContent) {
HttpContent content = (HttpContent) msg;
ByteBuf buf = content.content();
System.out.println(buf.toString(io.netty.util.CharsetUtil.UTF_8));
buf.release();
}
}
}