338 lines
7.6 KiB
Markdown
338 lines
7.6 KiB
Markdown
# Nacos注册中心
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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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for (String service : discoveryClient.getServices()) {
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System.out.println(service);
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for (ServiceInstance instance : discoveryClient.getInstances(service)) {
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System.out.println("IP地址：" + instance.getHost());
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System.out.println("端口号" + instance.getPort());
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}
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}
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System.out.println("----------------------------------------------");
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// 两个方式一样，DiscoveryClient 是 Spring自带的 NacosDiscoveryClient是 Nacos
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for (String service : nacosDiscoveryClient.getServices()) {
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System.out.println(service);
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for (ServiceInstance instance : nacosDiscoveryClient.getInstances(service)) {
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System.out.println("IP地址：" + instance.getHost());
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System.out.println("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，使用了nacos，可以使用`RestTemplate`，其中`RestTemplate`是线程安全的，只要注册一次全局都是可以使用。
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**RestTemplate源码**
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继承了`InterceptingHttpAccessor`，在`InterceptingHttpAccessor`中，使用了单例模式。
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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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##### 普通方式调用
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注册`RestTemplate`
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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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如果我们的服务启动了多个，在下面代码中即使一个服务宕机也可以做到远程调用。
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```java
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private Product getProductFromRemote(Long productId) {
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// 获取商品服务所有及其的 IP+port
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List<ServiceInstance> instances = discoveryClient.getInstances("service-product");
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ServiceInstance instance = instances.get(0);
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// 远程URL
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String url = "http://" + instance.getHost() + ":" + instance.getPort() + "/api/product/" + productId;
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// 2. 远程发送请求
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log.info("远程调用：{}", 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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注册`RestTemplate`
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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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使用负载均衡`LoadBalancerClient`，通过负载均衡算法动态调用远程服务。
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```java
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/**
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* 远程调用商品模块 --- 负载均衡
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*
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* @param productId 商品id
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* @return 商品对象
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*/
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private Product getProductFromRemoteWithLoadBalancer(Long productId) {
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// 1. 获取商品服务所有及其的 IP+port
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ServiceInstance instance = loadBalancerClient.choose("service-product");
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// 远程URL
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String url = "http://" + instance.getHost() + ":" + instance.getPort() + "/api/product/" + productId;
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// 2. 远程发送请求
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log.info("负载均衡远程调用：{}", url);
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return restTemplate.getForObject(url, Product.class);
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}
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```
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##### 负载均衡注解调用
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> [!TIP]
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>
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> 如果远程注册中心宕机是否可以调用？
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>
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> 调用过：远程调用不在依赖注册中心，可以通过。
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>
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> 没调用过：第一次发起远程调用；不能通过。
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在`RestTemplate`上加上`@LoadBalanced`注解使用负载均衡。
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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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在实际的调用中并不需要再显式调用，将URL替换成服务名称即可。
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```java
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/**
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* 远程调用商品模块 --- 负载均衡注解调用
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*
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* @param productId 商品id
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* @return 商品对象
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*/
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private Product getProductFromRemoteWithLoadBalancerAnnotation(Long productId) {
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// 远程URL，实现动态替换
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String url = "http://service-product/api/product/" + productId;
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// 远程发送请求
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log.info("负载均衡注解调用：{}", url);
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return restTemplate.getForObject(url, Product.class);
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}
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```
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## 按需加载
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### 数据隔离架构
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### 命名空间管理
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#### 创建命名空间
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> [!TIP]
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> 预配置的命名空间示例可在项目 `samples/namespace-config` 目录下找到。
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建议创建以下标准命名空间：
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- `dev` - 开发环境
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- `test` - 测试环境
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- `prod` - 生产环境
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**操作步骤**：
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1. 进入Nacos控制台命名空间管理
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2. 点击"新建命名空间"
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3. 填写命名空间信息（ID和名称）
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#### 配置管理
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**开发环境配置示例**：
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1. 基础配置：
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```yaml
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order:
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timeout: 1min
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auto-confirm: 1h
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```
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2. 数据库配置：
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```yaml
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order:
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db-url: jdbc:mysql://dev-db:3306/order_dev
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```
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#### 命名空间克隆
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通过克隆功能快速创建相似环境的命名空间：
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### 动态环境配置
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#### Spring Boot 配置方案
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**基础配置**：
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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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cloud:
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nacos:
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server-addr: ${NACOS_HOST:192.168.95.135}:8848
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config:
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namespace: ${spring.profiles.active:dev} # 动态匹配当前profile
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group: DEFAULT_GROUP
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```
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**多环境配置加载**：
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```yaml
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spring:
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config:
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import:
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- optional:nacos:service-order.yml
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- optional:nacos:common.yml?group=order
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- optional:nacos:database.yml?group=order
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```
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> [!NOTE]
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> 使用`optional:`前缀可避免配置不存在时启动失败
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### 配置读取实现
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**配置类**：
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```java
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@Configuration
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@ConfigurationProperties(prefix = "order")
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@Getter
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@Setter
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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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private String dbUrl; // 自动映射db-url
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}
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```
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**REST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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private final OrderProperties orderProperties;
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@GetMapping("/config")
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public Map<String, String> getConfig() {
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return Map.of(
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"timeout", orderProperties.getTimeout(),
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"autoConfirm", orderProperties.getAutoConfirm(),
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"dbUrl", orderProperties.getDbUrl()
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);
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}
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}
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```
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### 按需加载策略
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#### 多环境差异化配置
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```yaml
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spring:
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profiles:
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active: prod # 可通过启动参数覆盖
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---
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# 生产环境配置
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spring:
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config:
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import:
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- nacos:service-order-prod.yml
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- nacos:common-prod.yml?group=order
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activate:
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on-profile: prod
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---
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# 开发环境配置
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spring:
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config:
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import:
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- nacos:service-order-dev.yml
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- nacos:database-dev.yml?group=order
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activate:
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on-profile: dev
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---
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# 测试环境配置
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spring:
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config:
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import:
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- nacos:service-order-test.yml
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- nacos:database-test.yml?group=order
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activate:
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on-profile: test
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```
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