小马哥Java分布式架构训练营第一期服务治理
download：3w 51xuebc com使用Netty和Spring Boot实现仿微信的示例
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
第二步：创建数据库模型
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。
@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
}@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。
@Component
public 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。
@Component
public 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。
@Component
@ChannelHandler.Sharable
public 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 =