Netty開發 —— 首個demo學習
阿新 • • 發佈：2020-07-30
1. 編寫服務端程式碼
編寫業務邏輯：讀取到客戶端的訊息時候，列印客戶端訊息，並給客戶端回覆一條訊息
import io.netty.bootstrap.ServerBootstrap;
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.NioServerSocketChannel;
public class DemoNettyServer {
public void bind(int port) throws Exception {
// 主執行緒組
EventLoopGroup bossGroup = new NioEventLoopGroup();
// 從執行緒組
EventLoopGroup workerGroup = new NioEventLoopGroup();
try {
// netty伺服器啟動類
ServerBootstrap serverBootstrap = new ServerBootstrap();
serverBootstrap.group(bossGroup, workerGroup) //繫結兩個執行緒組
// 用於構造socketchannel工廠
.channel(NioServerSocketChannel.class) //指定NIO的模式
.childHandler(new ChannelInitializer<SocketChannel>() { // 子處理器，用於處理workerGroup
protected void initChannel(SocketChannel socketChannel) throws Exception {
socketChannel.pipeline().addLast(new DemoNettyServerHandler());
}
});
// 啟動server，繫結埠
ChannelFuture channelFuture = serverBootstrap.bind(8088).sync();
System.out.println("server start");
// 監聽關閉的channel，等待伺服器 socket 關閉 。設定位同步方式
channelFuture.channel().closeFuture().sync();
System.out.println("server close");
} finally {
//退出執行緒組
bossGroup.shutdownGracefully();
workerGroup.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
int port = 8080;
new DemoNettyServer().bind(port);
}
}
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class DemoNettyServerHandler extends ChannelInboundHandlerAdapter {
/**
* 本方法用於讀取客戶端傳送的資訊
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("收到來自客服端的一條訊息");
ByteBuf result = (ByteBuf) msg;
byte[] bytesMsg = new byte[result.readableBytes()];
// msg中儲存的是ByteBuf型別的資料，把資料讀取到byte[]中
result.readBytes(bytesMsg);
String resultStr = new String(bytesMsg);
// 接收並列印客戶端的資訊
System.out.println("客服端內容:" + resultStr);
// 釋放資源，這行很關鍵
result.release();
// 向客戶端傳送訊息
String response = "我是server，我已經收到你的訊息： " + resultStr;
// 在當前場景下，傳送的資料必須轉換成ByteBuf陣列
ByteBuf encoded = ctx.alloc().buffer(4 * response.length());
encoded.writeBytes(response.getBytes());
ctx.write(encoded);
ctx.flush();
}
/**
* 本方法用作處理異常
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
// 當出現異常就關閉連線
cause.printStackTrace();
ctx.close();
}
/**
* 資訊獲取完畢後操作
*/
@Override
public void channelReadComplete(ChannelHandlerContext ctx) throws Exception {
ctx.flush();
}
}
2. 編寫客戶端程式碼
編寫業務邏輯：獲取使用者輸入，連線服務端，傳送訊息，讀取服務端訊息，關閉連線。
import io.netty.bootstrap.Bootstrap;
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 java.util.Scanner;
public class DemoNettyClient {
public void connect(String host, int port) throws Exception {
EventLoopGroup worker = new NioEventLoopGroup();
try {
// 客戶端啟動類程式
Bootstrap bootstrap = new Bootstrap();
/**
*EventLoop的組
*/
bootstrap.group(worker);
/**
* 用於構造socketchannel工廠
*/
bootstrap.channel(NioSocketChannel.class);
/**設定選項
* 引數：Socket的標準引數（key，value），可自行百度
保持呼吸，不要斷氣！
* */
bootstrap.option(ChannelOption.SO_KEEPALIVE, true);
/**
* 自定義客戶端Handle（客戶端在這裡搞事情）
*/
bootstrap.handler(new ChannelInitializer<SocketChannel>() {
@Override
public void initChannel(SocketChannel ch) throws Exception {
ch.pipeline().addFirst(new DemoNettyClientHandler());
}
});
/** 開啟客戶端監聽，連線到遠端節點，阻塞等待直到連線完成*/
ChannelFuture channelFuture = bootstrap.connect(host, port).sync();
/**阻塞等待資料，直到channel關閉(客戶端關閉)*/
channelFuture.channel().closeFuture().sync();
} finally {
worker.shutdownGracefully();
}
}
public static void main(String[] args) throws Exception {
while (true){
Scanner content = new Scanner(System.in);
System.out.print("請輸入您要傳送的內容: ");
Meesage.CLIENT_MESSAGE = content.nextLine();
DemoNettyClient client = new DemoNettyClient();
client.connect("127.0.0.1", 8088);
}
}
}
import io.netty.buffer.ByteBuf;
import io.netty.channel.ChannelHandlerContext;
import io.netty.channel.ChannelInboundHandlerAdapter;
public class DemoNettyClientHandler extends ChannelInboundHandlerAdapter {
/**
* 服務端發過來訊息時呼叫
*/
@Override
public void channelRead(ChannelHandlerContext ctx, Object msg) throws Exception {
System.out.println("收到來自服務端的一條訊息");
ByteBuf result = (ByteBuf) msg;
byte[] result1 = new byte[result.readableBytes()];
result.readBytes(result1);
System.out.println(new String(result1));
result.release();
//關閉連線
ctx.close();
}
/**
* 異常時呼叫
*/
@Override
public void exceptionCaught(ChannelHandlerContext ctx, Throwable cause) throws Exception {
cause.printStackTrace();
ctx.close();
}
/**
* 連線到伺服器呼叫
*/
@Override
public void channelActive(ChannelHandlerContext ctx) throws Exception {
String msg = Meesage.CLIENT_MESSAGE;
ByteBuf encoded = ctx.alloc().buffer(4 * msg.length());
encoded.writeBytes(msg.getBytes());
ctx.write(encoded);
ctx.flush();
}
}
public class Meesage {
public static String CLIENT_MESSAGE = "";
public static String SERVER_MESSAGE = "";
}
3. 結果分析