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‎spring-cloud/lesson-2/README.md

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## Environment
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`Environment`: `PropertySources` = 1:1
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`PropertySources`: `PropertySource` = 1:N
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[0] `PropertySource` （Map）
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​ spring.application.name = spring-cloud-config-client
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[1] `PropertySource`（Map）
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​ spring.application.name = spring-cloud-config-client-demo
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### Spring Boot 配置文件
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#### application.properties 或 application.xml
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加载器：`PropertiesPropertySourceLoader`
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#### application.yml 或者 application.yaml
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加载器：`YamlPropertySourceLoader`
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## Environment 端点
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### 请求 URI ：`/env`
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数据来源：`EnvironmentEndpoint`
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Controller 来源：`EnvironmentMvcEndpoint`
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## Bootstrap 配置
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参考`BootstrapApplicationListener` 实现
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> 注：程序启动参数的加载逻辑：
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>
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> `SpringApplication#configurePropertySources()`
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## Bootstrap 配置文件
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```java
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String configName = environment.resolvePlaceholders("${spring.cloud.bootstrap.name:bootstrap}");
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```
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当 `spring.cloud.bootstrap.name` 存在时，使用该配置项，否则，使用 "bootstrap" 作为默认
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```properties
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## application.properties
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## 通过调整 spring.cloud.bootstrap.enabled = false，尝试关闭 bootstrap 上下文
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## 实际测试结果，没有效果
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spring.cloud.bootstrap.enabled = false
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```
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> 注意：`BootstrapApplicationListener` 加载实际早于 `ConfigFileApplicationListener`
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>
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> 原因是：
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>
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> `ConfigFileApplicationListener` 的 Order = Ordered.HIGHEST_PRECEDENCE + 10（第十一位）
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>
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> `BootstrapApplicationListener`的 Order = Ordered.HIGHEST_PRECEDENCE + 5（第六位）
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如果需要调整 控制 Bootstrap 上下文行为配置，需要更高优先级，也就是说 Order 需要 < Ordered.HIGHEST_PRECEDENCE + 5 (越小越优先)，比如使用程序启动参数：
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```
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--spring.cloud.bootstrap.enabld = true
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```
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### 调整 Bootstrap 配置
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#### 调整 Bootstrap 配置文件名称
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调整程序启动参数
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```
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--spring.cloud.bootstrap.name=spring-cloud
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```
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bootstrap 配置文件名称发生了改变"spring-cloud"，现有三个文件：
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* `application.properties`
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* **spring.application.name = spring-cloud-config-client**
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* `bootstrap.properties`
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* spring.application.name = spring-cloud-config-client-demo
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* `spring-cloud.properties`
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* **spring.application.name = spring-cloud**
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运行结果（部分）：
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```json
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"applicationConfig: [classpath:/application.properties]": {
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"spring.cloud.bootstrap.enabled": "false",
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"endpoints.env.sensitive": "false",
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"spring.application.name": "spring-cloud-config-client"
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},
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...
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"applicationConfig: [classpath:/spring-cloud.properties]": {
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"spring.application.name": "spring-cloud-config-client"
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}
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```
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#### 调整 Bootstrap 配置文件路径
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保留 **Bootstrap 配置文件名称** 程序启动参数：
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```properties
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--spring.cloud.bootstrap.name=spring-cloud
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```
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调整 **Bootstrap 配置文件路径** 程序启动参数：
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```properties
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--spring.cloud.bootstrap.location=config
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```
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现有四个文件：
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* `application.properties`
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* **spring.application.name = spring-cloud-config-client**
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* `bootstrap.properties`
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* spring.application.name = spring-cloud-config-client-demo
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* `spring-cloud.properties`
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* **spring.application.name = spring-cloud**
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* `config/spring-cloud.properties`
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* **spring.application.name = spring-cloud-2**
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实际结果：
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```json
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"applicationConfig: [classpath:/application.properties]": {
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"spring.cloud.bootstrap.enabled": "false",
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"endpoints.env.sensitive": "false",
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"spring.application.name": "spring-cloud-config-client"
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},
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...
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"applicationConfig: [classpath:/config/spring-cloud.properties]": {
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"spring.application.name": "spring-cloud-config-client"
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},
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"applicationConfig: [classpath:/spring-cloud.properties]": {
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"spring.application.name": "spring-cloud-config-client"
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},
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```
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#### 覆盖远程配置属性
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默认情况，Spring Cloud 是允许覆盖的，`spring.cloud.config.allowOverride=true`
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通过程序启动参数，调整这个值为"**false**"
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```properties
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--spring.cloud.config.allowOverride=false
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```
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启动后，重新Postman 发送 POST 请求，调整`spring.application.name` 值为 "**spring-cloud-new**"
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> 注意官方文档的说明：the remote property source has to grant it permission by setting `spring.cloud.config.allowOverride=true` (it doesn’t work to set this locally).
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#### 自定义 Bootstrap 配置
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1. 创建`META-INF/spring.factories`文件（类似于 Spring Boot 自定义 Starter）
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2. 自定义 Bootstrap 配置 Configuration
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```java
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package com.segmentfault.springcloudlesson2.boostrap;
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import org.springframework.context.ApplicationContextInitializer;
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import org.springframework.context.ConfigurableApplicationContext;
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import org.springframework.context.annotation.Configuration;
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import org.springframework.core.env.ConfigurableEnvironment;
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import org.springframework.core.env.MapPropertySource;
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import org.springframework.core.env.MutablePropertySources;
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import org.springframework.core.env.PropertySource;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* Bootstrap 配置 Bean
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*
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* @author <a href="mailto:mercyblitz@gmail.com">Mercy</a>
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* @since Configuration
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*/
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@Configuration
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public class MyConfiguration implements ApplicationContextInitializer {
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@Override
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public void initialize(ConfigurableApplicationContext applicationContext) {
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// 从 ConfigurableApplicationContext 获取 ConfigurableEnvironment 实例
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ConfigurableEnvironment environment = applicationContext.getEnvironment();
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// 获取 PropertySources
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MutablePropertySources propertySources = environment.getPropertySources();
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// 定义一个新的 PropertySource，并且放置在首位
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propertySources.addFirst(createPropertySource());
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}
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private PropertySource createPropertySource() {
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Map<String, Object> source = new HashMap<>();
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source.put("name", "小马哥");
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PropertySource propertySource = new MapPropertySource("my-property-source", source);
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return propertySource;
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}
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}
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```
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​
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3. 配置`META-INF/spring.factories`文件，关联Key `org.springframework.cloud.bootstrap.BootstrapConfiguration`
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```properties
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org.springframework.cloud.bootstrap.BootstrapConfiguration= \
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com.segmentfault.springcloudlesson2.boostrap.MyConfiguration
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```
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​
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​
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#### 自定义 Bootstrap 配置属性源
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1. 实现`PropertySourceLocator`
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```java
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package com.segmentfault.springcloudlesson2.boostrap;
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import org.springframework.cloud.bootstrap.config.PropertySourceLocator;
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import org.springframework.core.env.*;
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import java.util.HashMap;
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import java.util.Map;
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/**
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* 自定义 {@link PropertySourceLocator} 实现
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*
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* @author <a href="mailto:mercyblitz@gmail.com">Mercy</a>
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* @since PropertySourceLocator
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*/
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public class MyPropertySourceLocator implements PropertySourceLocator {
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@Override
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public PropertySource<?> locate(Environment environment) {
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if (environment instanceof ConfigurableEnvironment) {
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ConfigurableEnvironment configurableEnvironment = ConfigurableEnvironment.class.cast(environment);
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// 获取 PropertySources
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MutablePropertySources propertySources = configurableEnvironment.getPropertySources();
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// 定义一个新的 PropertySource，并且放置在首位
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propertySources.addFirst(createPropertySource());
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}
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return null;
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}
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private PropertySource createPropertySource() {
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Map<String, Object> source = new HashMap<>();
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source.put("spring.application.name", "小马哥的 Spring Cloud 程序");
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// 设置名称和来源
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PropertySource propertySource = new MapPropertySource("over-bootstrap-property-source", source);
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return propertySource;
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}
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}
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```
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​
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2. 配置`META-INF/spring.factories`
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```properties
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org.springframework.cloud.bootstrap.BootstrapConfiguration= \
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com.segmentfault.springcloudlesson2.boostrap.MyConfiguration,\
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com.segmentfault.springcloudlesson2.boostrap.MyPropertySourceLocator
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```
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​
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‎spring-cloud/lesson-2/[课件] Spring Cloud 配置客户端.pdf

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‎spring-cloud/lesson-2/spring-cloud-lesson-2/.gitignore

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target/
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!.mvn/wrapper/maven-wrapper.jar
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### STS ###
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.apt_generated
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.classpath
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.factorypath
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.project
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.settings
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.springBeans
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### IntelliJ IDEA ###
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.idea
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*.iws
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*.iml
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*.ipr
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### NetBeans ###
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nbproject/private/
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build/
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nbbuild/
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dist/
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nbdist/
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.nb-gradle/

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