Dubbo

概述

Dubbo 是阿里开源的高性能 RPC 框架，提供服务注册、发现、调用、负载均衡等功能。

架构

┌─────────────────────────────────────────────────────────┐
│                    Dubbo 架构                           │
├─────────────────────────────────────────────────────────┤
│                                                         │
│    ┌──────────┐         ┌──────────┐                   │
│    │ Consumer │ ──────> │ Provider │                   │
│    └──────────┘         └──────────┘                   │
│         │                    │                          │
│         │    ┌──────────┐    │                          │
│         └──> │ Registry │ <──┘                          │
│              └──────────┘                               │
│                   │                                     │
│              ┌──────────┐                               │
│              │ Monitor  │                               │
│              └──────────┘                               │
│                                                         │
└─────────────────────────────────────────────────────────┘

快速开始

定义接口

// API 模块
public interface UserService {
    User getUser(Long id);
    List<User> listUsers();
    void createUser(User user);
}

服务提供者

// Provider 模块
@DubboService(version = "1.0.0")
public class UserServiceImpl implements UserService {
    
    @Override
    public User getUser(Long id) {
        return userRepository.findById(id).orElse(null);
    }
    
    @Override
    public List<User> listUsers() {
        return userRepository.findAll();
    }
    
    @Override
    public void createUser(User user) {
        userRepository.save(user);
    }
}

# application.yml
dubbo:
  application:
    name: user-provider
  registry:
    address: nacos://localhost:8848
  protocol:
    name: dubbo
    port: 20880
  scan:
    base-packages: com.example.service

服务消费者

// Consumer 模块
@RestController
public class UserController {
    
    @DubboReference(version = "1.0.0")
    private UserService userService;
    
    @GetMapping("/users/{id}")
    public User getUser(@PathVariable Long id) {
        return userService.getUser(id);
    }
}

# application.yml
dubbo:
  application:
    name: user-consumer
  registry:
    address: nacos://localhost:8848

高级特性

负载均衡

// 随机（默认）
@DubboReference(loadbalance = "random")

// 轮询
@DubboReference(loadbalance = "roundrobin")

// 最少活跃
@DubboReference(loadbalance = "leastactive")

// 一致性哈希
@DubboReference(loadbalance = "consistenthash")

集群容错

// 失败自动切换（默认）
@DubboReference(cluster = "failover", retries = 2)

// 快速失败
@DubboReference(cluster = "failfast")

// 失败安全
@DubboReference(cluster = "failsafe")

// 并行调用
@DubboReference(cluster = "forking", forks = 2)

服务降级

@DubboReference(mock = "com.example.UserServiceMock")
private UserService userService;

// Mock 实现
public class UserServiceMock implements UserService {
    @Override
    public User getUser(Long id) {
        return new User(-1L, "降级用户");
    }
}

超时配置

// 方法级别
@DubboService(timeout = 3000, methods = {
    @Method(name = "getUser", timeout = 1000),
    @Method(name = "listUsers", timeout = 5000)
})

// 消费端
@DubboReference(timeout = 3000)

异步调用

// 定义异步接口
public interface UserService {
    CompletableFuture<User> getUserAsync(Long id);
}

// 使用
@DubboReference
private UserService userService;

public void asyncCall() {
    CompletableFuture<User> future = userService.getUserAsync(1L);
    future.whenComplete((user, throwable) -> {
        if (throwable != null) {
            // 处理异常
        } else {
            // 处理结果
        }
    });
}

泛化调用

// 不依赖接口，动态调用
@DubboReference(interfaceClass = GenericService.class, generic = true)
private GenericService genericService;

public Object invoke() {
    return genericService.$invoke(
        "getUser",
        new String[]{"java.lang.Long"},
        new Object[]{1L}
    );
}

服务治理

路由规则

# 条件路由
conditions:
  - "host = 192.168.1.* => host = 192.168.1.*"
  - "method = getUser => host = 192.168.1.1"

动态配置

# 覆盖规则
configVersion: v2.7
scope: service
key: com.example.UserService
enabled: true
configs:
  - side: consumer
    parameters:
      timeout: 5000

完整配置

dubbo:
  application:
    name: user-service
    qos-enable: false
  registry:
    address: nacos://localhost:8848
    timeout: 10000
  protocol:
    name: dubbo
    port: 20880
    threads: 200
  provider:
    timeout: 3000
    retries: 0
    loadbalance: random
  consumer:
    timeout: 3000
    retries: 2
    check: false
  scan:
    base-packages: com.example.service