364 lines
8.6 KiB
Markdown
364 lines
8.6 KiB
Markdown
# 微服务文档
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## 注册中心
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### 服务发现
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发现服务信息。
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```java
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@SpringBootTest()
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public class DiscoveryTest {
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@Autowired
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private DiscoveryClient discoveryClient;
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@Autowired
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private NacosDiscoveryClient nacosDiscoveryClient;
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@Test
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void discoveryClientTest() {
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// 使用Spring Cloud标准DiscoveryClient
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for (String service : discoveryClient.getServices()) {
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System.out.println("服务名称: " + service);
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for (ServiceInstance instance : discoveryClient.getInstances(service)) {
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System.out.println("实例IP地址: " + instance.getHost());
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System.out.println("实例端口号: " + instance.getPort());
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}
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}
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System.out.println("----------------------------------------------");
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// 使用Nacos专用DiscoveryClient
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for (String service : nacosDiscoveryClient.getServices()) {
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System.out.println("服务名称: " + service);
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for (ServiceInstance instance : nacosDiscoveryClient.getInstances(service)) {
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System.out.println("实例IP地址: " + instance.getHost());
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System.out.println("实例端口号: " + instance.getPort());
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}
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}
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}
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}
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```
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### 远程调用
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订单模块调用远程商品模块，使用Nacos作为注册中心，可以使用`RestTemplate`进行远程调用。`RestTemplate`是线程安全的，只需注册一次即可全局使用。
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**RestTemplate线程安全说明**
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`RestTemplate`继承了`InterceptingHttpAccessor`，其中使用了单例模式保证线程安全：
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```java
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public ClientHttpRequestFactory getRequestFactory() {
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List<ClientHttpRequestInterceptor> interceptors = this.getInterceptors();
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if (!CollectionUtils.isEmpty(interceptors)) {
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ClientHttpRequestFactory factory = this.interceptingRequestFactory;
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if (factory == null) {
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factory = new InterceptingClientHttpRequestFactory(super.getRequestFactory(), interceptors);
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this.interceptingRequestFactory = factory;
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}
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return factory;
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} else {
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return super.getRequestFactory();
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}
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}
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```
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#### 实现远程调用
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##### 基础调用方式
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1. 注册`RestTemplate` Bean：
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```java
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@Bean
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public RestTemplate restTemplate() {
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return new RestTemplate();
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}
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```
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2. 实现远程调用：
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```java
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private Product getProductFromRemote(Long productId) {
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// 获取商品服务所有实例
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List<ServiceInstance> instances = discoveryClient.getInstances("service-product");
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if (instances.isEmpty()) {
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throw new RuntimeException("未找到可用的商品服务实例");
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}
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ServiceInstance instance = instances.get(0);
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String url = "http://" + instance.getHost() + ":" + instance.getPort() + "/api/product/" + productId;
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log.info("远程调用商品服务: {}", url);
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return restTemplate.getForObject(url, Product.class);
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}
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```
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##### 负载均衡调用
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1. 注册`RestTemplate` Bean：
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```java
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@Bean
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public RestTemplate restTemplate() {
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return new RestTemplate();
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}
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```
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2. 使用`LoadBalancerClient`实现负载均衡：
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```java
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/**
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* 使用负载均衡调用远程商品服务
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*
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* @param productId 商品ID
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* @return 商品信息
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*/
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private Product getProductFromRemoteWithLoadBalancer(Long productId) {
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ServiceInstance instance = loadBalancerClient.choose("service-product");
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String url = "http://" + instance.getHost() + ":" + instance.getPort() + "/api/product/" + productId;
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log.info("负载均衡远程调用商品服务: {}", url);
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return restTemplate.getForObject(url, Product.class);
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}
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```
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##### 注解式负载均衡调用
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> [!TIP]
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> 关于注册中心宕机的影响：
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> - 已调用过的服务：可以继续调用，因为客户端有缓存
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> - 未调用过的服务：首次调用会失败，因为需要从注册中心获取服务列表
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1. 注册带负载均衡的`RestTemplate`：
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```java
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@Bean
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@LoadBalanced
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public RestTemplate restTemplate() {
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return new RestTemplate();
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}
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```
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2. 直接使用服务名进行调用：
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```java
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/**
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* 使用注解式负载均衡调用远程商品服务
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*
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* @param productId 商品ID
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* @return 商品信息
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*/
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private Product getProductFromRemoteWithLoadBalancerAnnotation(Long productId) {
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String url = "http://service-product/api/product/" + productId;
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log.info("负载均衡注解调用商品服务: {}", url);
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return restTemplate.getForObject(url, Product.class);
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}
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```
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### 远程配置管理
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#### 基础配置
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1. 添加依赖：
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```xml
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<dependency>
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<groupId>com.alibaba.cloud</groupId>
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<artifactId>spring-cloud-starter-alibaba-nacos-config</artifactId>
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</dependency>
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```
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2. 在Nacos中配置：
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配置内容示例：
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```yaml
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order:
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timeout: 30min
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auto-confirm: true
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```
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3. 创建配置读取接口：
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```java
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@RestController
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@RequestMapping("/api/order")
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@RequiredArgsConstructor
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public class OrderController {
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@Value("${order.timeout}")
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private String timeout;
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@Value("${order.auto-confirm}")
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private String autoConfirm;
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@Operation(summary = "读取配置")
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@GetMapping("config")
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public String config() {
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return "timeout: " + timeout + "\nautoConfirm: " + autoConfirm;
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}
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}
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```
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4. 应用配置：
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```yaml
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server:
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port: 8000
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spring:
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application:
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name: service-order
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profiles:
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active: dev
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config:
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import:
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- nacos:service-order.yml
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cloud:
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nacos:
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server-addr: 192.168.95.135:8848
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config:
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import-check:
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enabled: false
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```
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> [!CAUTION]
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> 注意事项：
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> - 不要在`server-addr`中使用变量引用如`${nacos.server-addr}`，这可能导致连接失败
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> - 对于不需要动态配置的模块，可以禁用配置检查
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#### 动态刷新配置
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1. 添加`@RefreshScope`注解：
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```java
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@SpringBootApplication
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@EnableDiscoveryClient
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@RefreshScope
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public class ProductServiceApplication {
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public static void main(String[] args) {
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SpringApplication.run(ProductServiceApplication.class, args);
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}
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}
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```
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#### 批量配置绑定
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> [!TIP]
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> 使用`@ConfigurationProperties`批量绑定配置：
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> - 无需`@RefreshScope`即可实现动态刷新
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> - 支持中划线命名自动转为驼峰命名
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1. 创建配置类：
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```java
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@Configuration
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@ConfigurationProperties(prefix = "order")
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public class OrderProperties {
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private String timeout;
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private String autoConfirm;
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// getters and setters
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}
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```
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2. 使用配置：
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```java
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@RestController
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@RequestMapping("/api/order")
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@RequiredArgsConstructor
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public class OrderController {
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private final OrderProperties orderProperties;
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@Operation(summary = "读取配置")
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@GetMapping("config")
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public String config() {
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return "timeout: " + orderProperties.getTimeout() +
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"\nautoConfirm: " + orderProperties.getAutoConfirm();
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}
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}
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```
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#### 高级配置管理
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1. 多环境配置：
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```yaml
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spring:
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profiles:
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active: @profileActive@
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config:
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import:
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- nacos:service-order-${spring.profiles.active}.yml
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```
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2. 共享配置：
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```yaml
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spring:
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config:
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import:
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- nacos:common-config.yml
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- nacos:service-order.yml
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```
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3. 命名空间和分组：
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```yaml
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cloud:
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nacos:
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config:
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namespace: dev
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group: DEFAULT_GROUP
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```
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4. 配置优先级：
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- 应用名-profile.yml (最高优先级)
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- 应用名.yml
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- 扩展配置
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- 共享配置 (最低优先级)
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### 配置监听
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#### 实现配置监听
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1. 项目启动时注册监听器：
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```java
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@SpringBootApplication
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@EnableDiscoveryClient
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public class OrderServiceApplication {
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public static void main(String[] args) {
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SpringApplication.run(OrderServiceApplication.class, args);
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}
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@Bean
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public ApplicationRunner runner(NacosConfigManager nacosConfigManager) {
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return args -> {
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ConfigService configService = nacosConfigManager.getConfigService();
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configService.addListener("service-order.yml", "DEFAULT_GROUP", new Listener() {
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@Override
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public Executor getExecutor() {
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return Executors.newFixedThreadPool(10);
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}
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@Override
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public void receiveConfigInfo(String configInfo) {
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System.out.println("配置变更内容: " + configInfo);
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// 实现配置变更后的处理逻辑
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System.out.println("发送配置变更通知邮件...");
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}
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});
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System.out.println("订单服务启动完成，配置监听已注册");
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};
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}
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}
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```
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