簡介
相比Netty3, Netty4有很多顯著的變化：
NioEventLoopGroup 是一個處理I/O操作的多線程事件環。即為Netty4裡的線程池，在3.x裡，一個Channel是由ChannelFactory創建的，同時新創建的Channel會自動注冊到一個隱藏的I/O線程。 4.0使用新的名為EventLoopGroup的接口來替換ChannelFactory，它由一個或多個EventLoop來構成。一個新的 Channel不會自動注冊到EventLoopGroup，但用戶可以顯式調用EventLoopGroup.register（）來注冊。在Server端的Bootstrap參數中，有兩個EventLoopGroup，第一個通常稱為'boss'，用於接收發來的連接請求。第二個稱為'worker',，用於處理boss接受並且注冊給worker的連接中的信息。
ChannelInitializer是一個特殊的handler，用於方便的配置用戶自定義的handler實現，如代碼中所示。在channelRegistered的生命周期中會觸發用戶復寫的initChannel(C ch)方法，並且在調用後會講自身從channelPipeline中移除。
代碼示例
import io.netty.bootstrap.ServerBootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
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;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
import io.netty.handler.logging.LogLevel;
import io.netty.handler.logging.LoggingHandler;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.util.SelfSignedCertificate;
/**
* DateTime: 2015年1月5日 上午9:56:10
*
*/
public class HelloWorldServer {
static final boolean SSL = System.getProperty("ssl") != null;
static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));
public static void main(String[] args) throws Exception {
// Configure SSL.
final SslContext sslCtx;
if (SSL) {
SelfSignedCertificate ssc = new SelfSignedCertificate();
sslCtx = SslContext.newServerContext(ssc.certificate(), ssc.privateKey());
} else {
sslCtx = null;
}
// Configure the server.
EventLoopGroup bossGroup = new NioEventLoopGroup(1);
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
ServerBootstrap b = new ServerBootstrap();
b.group(bossGroup, workerGroup)
.channel(NioServerSocketChannel.class)
.option(ChannelOption.SO_BACKLOG, 100)
.handler(new LoggingHandler(LogLevel.INFO))
.childHandler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
if (sslCtx != null) {
p.addLast(sslCtx.newHandler(ch.alloc()));
}
p.addLast(new LoggingHandler(LogLevel.INFO));
p.addLast(
new ObjectEncoder(),
new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
new HelloWorldServerHandler());
}
});
// Start the server.
ChannelFuture f = b.bind(PORT).sync();
// Wait until the server socket is closed.
f.channel().closeFuture().sync();
} finally {
// Shut down all event loops to terminate all threads.
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
}
class HelloWorldServerHandler extends ChannelInboundHandlerAdapter {
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
ctx.write("server write msg:"+msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// Close the connection when an exception is raised.
cause.printStackTrace();
ctx.close();
}
}
import io.netty.bootstrap.Bootstrap;
import io.netty.channel.ChannelFuture;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
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.NioSocketChannel;
import io.netty.handler.codec.serialization.ClassResolvers;
import io.netty.handler.codec.serialization.ObjectDecoder;
import io.netty.handler.codec.serialization.ObjectEncoder;
import io.netty.handler.ssl.SslContext;
import io.netty.handler.ssl.util.InsecureTrustManagerFactory;
/**
* DateTime: 2015年1月5日 上午9:56:22
*
*/
public class HelloWorldClient {
static final boolean SSL = System.getProperty("ssl") != null;
static final String HOST = System.getProperty("host", "127.0.0.1");
static final int PORT = Integer.parseInt(System.getProperty("port", "8007"));
public static void main(String[] args) throws Exception {
// Configure SSL.git
final SslContext sslCtx;
if (SSL) {
sslCtx = SslContext.newClientContext(InsecureTrustManagerFactory.INSTANCE);
}
else {
sslCtx = null;
}
// Configure the client.
EventLoopGroup group = new NioEventLoopGroup();
try {
Bootstrap b = new Bootstrap();
b.group(group).channel(NioSocketChannel.class).option(ChannelOption.TCP_NODELAY, true)
.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ChannelPipeline p = ch.pipeline();
if (sslCtx != null) {
p.addLast(sslCtx.newHandler(ch.alloc(), HOST, PORT));
}
p.addLast(new ObjectEncoder(), new ObjectDecoder(ClassResolvers.cacheDisabled(null)),
new HelloWorldClientHandler());
}
});
// Start the client.
ChannelFuture f = b.connect(HOST, PORT).sync();
// Wait until the connection is closed.
f.channel().closeFuture().sync();
}
finally {
// Shut down the event loop to terminate all threads.
group.shutdownGracefully();
}
}
}
class HelloWorldClientHandler extends ChannelInboundHandlerAdapter {
private final String msg = "hello java world";
/**
* Creates a client-side handler.
*/
public HelloWorldClientHandler() {
//TODO
}
@Override
public void channelActive(ChannelHandlerContext ctx) {
ctx.writeAndFlush(msg);
}
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) {
System.out.println(msg);
// ctx.write(msg);
}
@Override
public void channelReadComplete(ChannelHandlerContext ctx) {
ctx.flush();
}
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) {
// Close the connection when an exception is raised.
cause.printStackTrace();
ctx.close();
}
}
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