spring-cloud-alibaba

# Spring Cloud Alibaba 开发指南

## 概述

Spring Cloud Alibaba 是阿里巴巴提供的微服务解决方案，提供了 Nacos（服务注册与配置）、Sentinel（流量控制）、RocketMQ（消息队列）、Seata（分布式事务）等组件。

## 核心组件

### 1. Nacos（服务注册与配置中心）

**Nacos Server 安装**：

```bash
# 下载 Nacos
wget https://github.com/alibaba/nacos/releases/download/2.2.0/nacos-server-2.2.0.tar.gz

# 解压并启动
tar -xzf nacos-server-2.2.0.tar.gz
cd nacos/bin
sh startup.sh -m standalone
```

**服务注册**：

```java
@SpringBootApplication
@EnableDiscoveryClient
public class UserServiceApplication {
    public static void main(String[] args) {
        SpringApplication.run(UserServiceApplication.class, args);
    }
}
```

**application.yml**：

```yaml
spring:
  application:
    name: user-service
  cloud:
    nacos:
      discovery:
        server-addr: localhost:8848
        namespace: dev
        group: DEFAULT_GROUP
```

**配置管理**：

```yaml
spring:
  cloud:
    nacos:
      config:
        server-addr: localhost:8848
        file-extension: yaml
        namespace: dev
        group: DEFAULT_GROUP
        shared-configs:
          - data-id: common-config.yaml
            group: DEFAULT_GROUP
            refresh: true
```

**动态配置刷新**：

```java
@RestController
@RefreshScope
public class ConfigController {
    @Value("${app.name:default}")
    private String appName;
    
    @GetMapping("/config")
    public String getConfig() {
        return appName;
    }
}
```

### 2. Sentinel（流量控制）

**依赖**：

```xml
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>
```

**配置**：

```yaml
spring:
  cloud:
    sentinel:
      transport:
        dashboard: localhost:8080
        port: 8719
      datasource:
        flow:
          nacos:
            server-addr: localhost:8848
            dataId: ${spring.application.name}-flow-rules
            groupId: SENTINEL_GROUP
            rule-type: flow
```

**流量控制**：

```java
@Service
public class UserService {
    @SentinelResource(value = "getUser", blockHandler = "getUserBlockHandler")
    public User getUser(Long id) {
        return userRepository.findById(id)
            .orElseThrow(() -> new UserNotFoundException(id));
    }
    
    public User getUserBlockHandler(Long id, BlockException ex) {
        return new User(); // 降级处理
    }
}
```

**熔断降级**：

```java
@SentinelResource(
    value = "getUser",
    fallback = "getUserFallback",
    blockHandler = "getUserBlockHandler"
)
public User getUser(Long id) {
    // 业务逻辑
}

public User getUserFallback(Long id, Throwable ex) {
    // 降级处理
    return new User();
}
```

### 3. RocketMQ（消息队列）

**依赖**：

```xml
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-rocketmq</artifactId>
</dependency>
```

**配置**：

```yaml
spring:
  cloud:
    stream:
      rocketmq:
        binder:
          name-server: localhost:9876
        bindings:
          output:
            producer:
              group: user-service-group
```

**消息发送**：

```java
@Service
public class UserService {
    private final RocketMQTemplate rocketMQTemplate;
    
    public UserService(RocketMQTemplate rocketMQTemplate) {
        this.rocketMQTemplate = rocketMQTemplate;
    }
    
    public void sendUserCreatedEvent(User user) {
        rocketMQTemplate.convertAndSend("user-topic", user);
    }
}
```

**消息接收**：

```java
@Component
@RocketMQMessageListener(
    topic = "user-topic",
    consumerGroup = "user-consumer-group"
)
public class UserEventListener implements RocketMQListener<User> {
    @Override
    public void onMessage(User user) {
        // 处理消息
        System.out.println("Received user: " + user.getName());
    }
}
```

### 4. Seata（分布式事务）

**依赖**：

```xml
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>
```

**配置**：

```yaml
spring:
  cloud:
    alibaba:
      seata:
        tx-service-group: my-tx-group
        enabled: true

seata:
  enabled: true
  application-id: ${spring.application.name}
  tx-service-group: my-tx-group
  config:
    type: nacos
    nacos:
      server-addr: localhost:8848
      namespace: ""
      group: SEATA_GROUP
  registry:
    type: nacos
    nacos:
      server-addr: localhost:8848
      namespace: ""
      group: SEATA_GROUP
```

**使用 @GlobalTransactional**：

```java
@Service
public class OrderService {
    @GlobalTransactional
    public void createOrder(Order order) {
        // 1. 创建订单
        orderRepository.save(order);
        
        // 2. 扣减库存
        productService.reduceStock(order.getProductId(), order.getQuantity());
        
        // 3. 扣减余额
        accountService.deductBalance(order.getUserId(), order.getAmount());
    }
}
```

### 5. Dubbo（RPC 框架）

**依赖**：

```xml
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-dubbo</artifactId>
</dependency>
```

**配置**：

```yaml
spring:
  cloud:
    dubbo:
      application:
        name: user-service
      registry:
        address: nacos://localhost:8848
      protocol:
        name: dubbo
        port: 20880
```

**服务提供者**：

```java
@Service
@org.apache.dubbo.config.annotation.Service
public class UserServiceImpl implements UserService {
    public User getUser(Long id) {
        return userRepository.findById(id).orElseThrow();
    }
}
```

**服务消费者**：

```java
@Service
public class OrderService {
    @org.apache.dubbo.config.annotation.Reference
    private UserService userService;
    
    public Order createOrder(Long userId, Order order) {
        User user = userService.getUser(userId);
        // 创建订单逻辑
        return order;
    }
}
```

## 微服务架构示例

### 项目结构

```
microservices/
├── nacos-server/           # Nacos 服务
├── gateway/                # API 网关
├── user-service/           # 用户服务
├── order-service/          # 订单服务
└── product-service/        # 商品服务
```

### 配置示例

**统一配置管理**：

```yaml
# Nacos 配置中心
spring:
  cloud:
    nacos:
      config:
        server-addr: localhost:8848
        file-extension: yaml
        namespace: ${spring.profiles.active}
        group: DEFAULT_GROUP
        extension-configs:
          - data-id: common-datasource.yaml
            group: DEFAULT_GROUP
            refresh: true
          - data-id: common-redis.yaml
            group: DEFAULT_GROUP
            refresh: true
```

## 最佳实践

### 1. 服务注册

- 使用 Nacos 作为服务注册中心
- 配置合适的命名空间和分组
- 设置健康检查

### 2. 配置管理

- 使用 Nacos 配置中心统一管理
- 区分环境配置（dev、test、prod）
- 支持动态刷新

### 3. 流量控制

- 使用 Sentinel 进行流量控制
- 配置限流、熔断、降级规则
- 监控服务调用情况

### 4. 分布式事务

- 使用 Seata 处理分布式事务
- 合理使用 @GlobalTransactional
- 避免长事务

## 常用依赖

```xml
<!-- Nacos Discovery -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-discovery</artifactId>
</dependency>

<!-- Nacos Config -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
</dependency>

<!-- Sentinel -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-sentinel</artifactId>
</dependency>

<!-- RocketMQ -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-rocketmq</artifactId>
</dependency>

<!-- Seata -->
<dependency>
    <groupId>com.alibaba.cloud</groupId>
    <artifactId>spring-cloud-starter-alibaba-seata</artifactId>
</dependency>
```

## 示例 Prompt

- "如何使用 Spring Cloud Alibaba 构建微服务架构？"
- "Nacos 如何配置服务注册和配置管理？"
- "如何在 Spring Cloud Alibaba 中使用 Sentinel 进行流量控制？"
- "Spring Cloud Alibaba 中如何使用 Seata 处理分布式事务？"
- "如何配置 RocketMQ 消息队列？"