spring-cloud

# Spring Cloud 微服务开发指南

## 概述

Spring Cloud 是一套完整的微服务解决方案，提供了服务注册与发现、配置管理、网关、负载均衡、熔断器等组件。

## 核心组件

### 1. 服务注册与发现（Eureka）

**Eureka Server**：

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

**application.yml**：

```yaml
server:
  port: 8761

eureka:
  instance:
    hostname: localhost
  client:
    register-with-eureka: false
    fetch-registry: false
    service-url:
      defaultZone: http://${eureka.instance.hostname}:${server.port}/eureka/
```

**Eureka Client**：

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

**application.yml**：

```yaml
spring:
  application:
    name: user-service

eureka:
  client:
    service-url:
      defaultZone: http://localhost:8761/eureka/
```

### 2. 配置中心（Config Server）

**Config Server**：

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

**application.yml**：

```yaml
server:
  port: 8888

spring:
  cloud:
    config:
      server:
        git:
          uri: https://github.com/example/config-repo
          search-paths: '{application}'
```

**Config Client**：

```yaml
spring:
  application:
    name: user-service
  cloud:
    config:
      uri: http://localhost:8888
      name: user-service
      profile: dev
```

### 3. API 网关（Gateway）

**Gateway 配置**：

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

**application.yml**：

```yaml
spring:
  cloud:
    gateway:
      routes:
        - id: user-service