Spring Boot按需重载配置文件属性技术问询

Alright, let's tackle your requirement of on-demand loading and auto-reloading configuration properties in Spring Boot. Here's a step-by-step solution tailored to your existing setup:

1. 基础配置完善（确保@ConfigurationProperties生效） #

First, let's fix a common oversight: your GetValues class needs to be a Spring-managed bean. Add the @Component annotation so Spring can scan and initialize it, along with @RefreshScope to enable refresh capability:

@Component
@ConfigurationProperties
@RefreshScope
public class GetValues {
    private List<String> values;

    // Getters and Setters
    public List<String> getValues() {
        return values;
    }

    public void setValues(List<String> values) {
        this.values = values;
    }
}

2. 手动触发配置刷新（使用Actuator端点） #

The simplest way to reload properties on demand is using Spring Boot Actuator's /refresh endpoint. Here's how to set it up:

Step 2.1 添加Actuator依赖 #

Add the actuator starter to your build file:

Maven (pom.xml):

<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-actuator</artifactId>
</dependency>

Gradle (build.gradle):

implementation 'org.springframework.boot:spring-boot-starter-actuator'

Step 2.2 暴露Refresh端点 #

Update your application configuration (application.yml or application.properties) to expose the refresh endpoint:

management:
  endpoints:
    web:
      exposure:
        include: refresh

Step 2.3 触发刷新 #

Now you can reload properties by sending a POST request to http://your-app-url/actuator/refresh. You can also wrap this in your custom REST endpoint if needed:

@RestController
@RequestMapping("/config")
public class ConfigController {
    private final RefreshScope refreshScope;

    public ConfigController(RefreshScope refreshScope) {
        this.refreshScope = refreshScope;
    }

    @PostMapping("/refresh")
    public String triggerRefresh() {
        // Refresh all beans annotated with @RefreshScope
        refreshScope.refreshAll();
        // Or refresh only the GetValues bean: refreshScope.refresh("getValues")
        return "Configuration reloaded successfully";
    }
}

3. 自动监听配置文件变更（无需手动触发） #

If you want properties to reload automatically whenever test-properties.yml changes, you can use Spring's FileSystemWatcher to monitor the file. Here's how:

Step 3.1 创建文件监听配置 #

@Configuration
public class ConfigWatcherConfig {

    @Value("${spring.config.location}")
    private String configFilePath;

    @Bean
    public FileSystemWatcher configFileWatcher() {
        // Parse the file path (remove "file:" prefix)
        String rawPath = configFilePath.replace("file:", "");
        File configFile = new File(rawPath);
        File parentDir = configFile.getParentFile();

        // Initialize watcher with polling intervals
        FileSystemWatcher watcher = new FileSystemWatcher(true, Duration.ofMillis(500), Duration.ofMillis(500));
        watcher.addSourceDirectory(parentDir);
        watcher.addListener(new ConfigFileChangeListener());
        watcher.start();

        return watcher;
    }

    // Stop the watcher when the application shuts down
    @PreDestroy
    public void stopWatcher() throws Exception {
        configFileWatcher().stop();
    }
}

Step 3.2 创建文件变更监听器 #

@Component
public class ConfigFileChangeListener implements FileChangeListener {

    private final RefreshScope refreshScope;

    public ConfigFileChangeListener(RefreshScope refreshScope) {
        this.refreshScope = refreshScope;
    }

    @Override
    public void onChange(FileChangeEvent event) {
        // Check if the changed file is your target properties file
        if ("test-properties.yml".equals(event.getFile().getName())) {
            refreshScope.refreshAll();
            System.out.println("test-properties.yml updated - properties reloaded");
        }
    }
}

4. 验证配置加载 #

You can create a simple REST endpoint to verify the current values:

@RestController
@RequestMapping("/values")
public class ValuesController {
    private final GetValues getValues;

    public ValuesController(GetValues getValues) {
        this.getValues = getValues;
    }

    @GetMapping
    public List<String> getCurrentValues() {
        return getValues.getValues();
    }
}

Now, whenever you modify test-properties.yml, either send a POST to /actuator/refresh (manual) or let the file watcher trigger an auto-refresh, then call /values to see the updated list.

内容的提问来源于stack exchange，提问作者Bhagath