在本文中,我们将使用Netty和Spring Boot框架来创建一个简单的聊天应用程序,类似于微信。这个应用程序将支持多用户聊天和即时消息发送。下面让我们来一步步看看如何实现。
第一步:设置项目结构和依赖项首先,我们需要创建一个新的Spring Boot项目,并添加必要的依赖项。我们需要添加以下依赖项:
- Spring Boot Starter Web
- Spring Boot Starter Data JPA
- Netty
接下来,我们将创建一个数据库模型,表示用户和消息之间的关系。我们可以使用Hibernate框架来实现这个模型。
java复制代码@Entity@Table(name = "users")public class User { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @Column(name = "name", nullable = false, unique = true) private String name; // getters and setters }java复制代码
@Entity@Table(name = "messages")public class Message { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) private Long id; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "from_user_id", nullable = false) private User fromUser; @ManyToOne(fetch = FetchType.EAGER) @JoinColumn(name = "to_user_id", nullable = false) private User toUser; @Column(name = "content", nullable = false) private String content; // getters and setters }第三步:创建Netty服务器
接下来,我们将使用Netty框架来创建一个聊天服务器。我们需要定义一个ChannelInitializer类,用于初始化Netty的管道。
java复制代码@Componentpublic class ChatServerInitializer extends ChannelInitializer<SocketChannel> { private final ChatServerHandler chatServerHandler; @Autowired public ChatServerInitializer(ChatServerHandler chatServerHandler) { this.chatServerHandler = chatServerHandler; } @Override public void initChannel(SocketChannel ch) throws Exception { ChannelPipeline pipeline = ch.pipeline(); pipeline.addLast(new DelimiterBasedFrameDecoder(8192, Delimiters.lineDelimiter())); pipeline.addLast(new StringDecoder()); pipeline.addLast(new StringEncoder()); pipeline.addLast(chatServerHandler); }}
然后,我们需要创建一个Netty服务器,并将它绑定到一个端口上。
java复制代码@Componentpublic class ChatServer { private final EventLoopGroup bossGroup; private final EventLoopGroup workerGroup; private final ServerBootstrap serverBootstrap; @Autowired public ChatServer(ChatServerInitializer chatServerInitializer) { bossGroup = new NioEventLoopGroup(); workerGroup = new NioEventLoopGroup(); serverBootstrap = new ServerBootstrap(); serverBootstrap.group(bossGroup, workerGroup) .channel(NioServerSocketChannel.class) .childHandler(chatServerInitializer); } public void start(int port) throws InterruptedException { serverBootstrap.bind(port).sync().channel().closeFuture().sync(); } public void stop() { workerGroup.shutdownGracefully(); bossGroup.shutdownGracefully(); }}第四步:处理Netty消息
我们需要实现一个Handler类,用于处理Netty管道中的消息。在这个示例中,我们需要解析客户端发送的JSON消息,并将其保存到数据库中。
java复制代码@Component@ChannelHandler.Sharablepublic class ChatServerHandler extends SimpleChannelInboundHandler<String> { private final ObjectMapper objectMapper; private final UserService userService; private final MessageService messageService; @Autowired public ChatServerHandler(ObjectMapper objectMapper, UserService userService, MessageService messageService) { this.objectMapper = objectMapper; this.userService = userService; this.messageService = messageService; } @Override protected void channelRead0(ChannelHandlerContext ctx, String msg) throws Exception { JsonNode jsonNode = objectMapper.readTree(msg); if (!jsonNode.has("from") || !jsonNode.has("to") || !jsonNode.has("content")) { return; } User fromUser = userService.findByName(jsonNode.get("from").asText()); User toUser =Java 亿级项目架构设计与落地应用
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