add client

pom.xml

@@ -15,29 +15,33 @@
         <java.version>17</java.version>
         <maven.compiler.source>${java.version}</maven.compiler.source>
         <maven.compiler.target>${java.version}</maven.compiler.target>
+        <junit.version>4.13.2</junit.version>
+        <lombok.version>1.18.24</lombok.version>
+        <gson.version>2.9.1</gson.version>
+        <netty.version>4.1.82.Final</netty.version>
     </properties>
 
     <dependencies>
         <dependency>
             <groupId>junit</groupId>
             <artifactId>junit</artifactId>
-            <version>4.13.2</version>
+            <version>${junit.version}</version>
         </dependency>
         <dependency>
             <groupId>org.projectlombok</groupId>
             <artifactId>lombok</artifactId>
-            <version>1.18.24</version>
+            <version>${lombok.version}</version>
             <scope>provided</scope>
         </dependency>
         <dependency>
             <groupId>com.google.code.gson</groupId>
             <artifactId>gson</artifactId>
-            <version>2.9.1</version>
+            <version>${gson.version}</version>
         </dependency>
         <dependency>
             <groupId>io.netty</groupId>
             <artifactId>netty-all</artifactId>
-            <version>4.1.82.Final</version>
+            <version>${netty.version}</version>
         </dependency>
     </dependencies>
 

src/main/java/chat/client/ClientHandler.java

+package chat.client;
+
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.ChannelHandlerContext;
+import io.netty.channel.ChannelInboundHandlerAdapter;
+
+
+import java.util.Date;
+import java.util.UUID;
+import java.util.Date;
+
+/**
+ * @author <a href="mailto:410486047@qq.com">Grey</a>
+ * @date 2022/9/15
+ * @since
+ */
+public class ClientHandler extends ChannelInboundHandlerAdapter {
+    @Override
+    public void channelActive(ChannelHandlerContext ctx) throws Exception {
+        System.out.println(new Date() + ": 客户端开始登录");
+
+        // 创建登录对象
+        LoginRequestPacket loginRequestPacket = new LoginRequestPacket();
+        loginRequestPacket.setUserId(UUID.randomUUID().toString());
+        loginRequestPacket.setUsername("flash");
+        loginRequestPacket.setPassword("pwd");
+
+        // 编码
+        ByteBuf buffer = PacketCodeC.INSTANCE.encode(ctx.alloc(), loginRequestPacket);
+
+        // 写数据
+        ctx.channel().writeAndFlush(buffer);
+    }
+    @Override
+    public void channelRead(ChannelHandlerContext ctx, Object msg) {
+        ByteBuf byteBuf = (ByteBuf) msg;
+
+        Packet packet = PacketCodeC.INSTANCE.decode(byteBuf);
+
+        if (packet instanceof LoginResponsePacket) {
+            LoginResponsePacket loginResponsePacket = (LoginResponsePacket) packet;
+
+            if (loginResponsePacket.isSuccess()) {
+                System.out.println(new Date() + ": 客户端登录成功");
+            } else {
+                System.out.println(new Date() + ": 客户端登录失败，原因：" + loginResponsePacket.getReason());
+            }
+        }
+    }
+}

src/main/java/chat/client/NettyClient.java

+package chat.client;
+
+import io.netty.bootstrap.Bootstrap;
+import io.netty.buffer.ByteBuf;
+import io.netty.channel.Channel;
+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.nio.NioEventLoopGroup;
+import io.netty.channel.socket.nio.NioSocketChannel;
+import io.netty.util.AttributeKey;
+
+import java.nio.charset.StandardCharsets;
+import java.util.Date;
+import java.util.concurrent.TimeUnit;
+
+/**
+ * Netty 可自动重连的客户端，增加了IO处理逻辑
+ *
+ * @author <a href="mailto:410486047@qq.com">Grey</a>
+ * @date 2022/9/12
+ * @since
+ */
+public class NettyClient {
+    static final int MAX_RETRY = 6;
+    static final String HOST = "localhost";
+    static final int PORT = 8000;
+
+    public static void main(String[] args) throws InterruptedException {
+        Bootstrap bootstrap = new Bootstrap();
+
+        NioEventLoopGroup group = new NioEventLoopGroup();
+        bootstrap
+                // 指定线程模型
+                .group(group)
+                // 指定IO类型为NIO
+                .channel(NioSocketChannel.class)
+                // attr可以为客户端Channel绑定自定义属性
+                .attr(AttributeKey.newInstance("clientName"), "nettyClient")
+                // 连接的超时时间，如果超过这个时间，仍未连接到服务端，则表示连接失败
+                .option(ChannelOption.CONNECT_TIMEOUT_MILLIS, 5000)
+                // 表示是否开启TCP底层心跳机制，true表示开启
+                .option(ChannelOption.SO_KEEPALIVE, true)
+                // 是否开启Nagle算法，如果要求高实时性，有数据就马上发送，则为true
+                // 如果需要减少发送次数，减少网络交互，就设置为false
+                .option(ChannelOption.TCP_NODELAY, true)
+                // IO处理逻辑
+                .handler(new ChannelInitializer<>() {
+                    @Override
+                    protected void initChannel(Channel ch) {
+                        ch.pipeline().addLast(new ChannelInboundHandlerAdapter() {
+                            // 这个方法会在客户端连接建立成功之后被调用
+                            @Override
+                            public void channelActive(ChannelHandlerContext ctx) {
+                                System.out.println(new Date() + ": 客户端写出数据");
+                                // 包装成ByteBuf并发送到服务端
+                                // 注：Netty中的数据是以 ByteBuf 为单位的。
+                                ctx.channel().writeAndFlush(getByteBuf(ctx));
+                            }
+
+                            @Override
+                            public void channelRead(ChannelHandlerContext ctx, Object msg) {
+                                ByteBuf byteBuf = (ByteBuf) msg;
+                                System.out.println(new Date() + ": 客户端读取到的数据 -> " + byteBuf.toString(StandardCharsets.UTF_8));
+                            }
+
+                            private ByteBuf getByteBuf(ChannelHandlerContext ctx) {
+                                ByteBuf buffer = ctx.alloc().buffer();
+                                byte[] bytes = "hello world".getBytes(StandardCharsets.UTF_8);
+                                buffer.writeBytes(bytes);
+                                return buffer;
+                            }
+                        })
+                    }
+                });
+        connect(bootstrap, HOST, PORT, MAX_RETRY);
+    }
+
+    private static void connect(final Bootstrap bootstrap, final String host, final int port, int retry) {
+        bootstrap.connect(host, port).addListener(future -> {
+            if (future.isSuccess()) {
+                System.out.println("连接成功！");
+            } else if (retry == 0) {
+                System.err.println("重试次数已经使用完毕");
+            } else {
+                // 第几次重试
+                int order = (MAX_RETRY - retry) + 1;
+                // 本次的重试间隔
+                int delay = 1 << order;
+                System.out.println(new Date() + "： 连接失败，第" + order + "次重连...");
+                bootstrap.config().group().schedule(() -> connect(bootstrap, host, port, retry - 1), delay, TimeUnit.SECONDS);
+            }
+        });
+    }
+    // TEST
+
+}