介绍

在使用spring 时，动态更新配置是常见的，属性值更新，但是需要开启支持刷新功能，一个是spring.cloud.nacos.config.isRefreshEnabled=true; 这个值一般是默认的，可以在nacosConfigProperties这个类中看到。还要在扩展配置中开启refresh = true

spring
    cloud:
      nacos:
        config:
          server-addr: ${nacos-ip}
          extension-configs[0]:
            data-id: ${spring.application.name}.yml
            group: base
        # 这个地方必须开启，否则不会自动刷新
            refresh: true

2 使用

2.1 新建配置类

import lombok.Data;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.context.annotation.Configuration;

@Data
@Configuration
@ConfigurationProperties(prefix = "apply.demo")
public class DemoConfig {

    /**
     * 配置信息
     */
    private String config;
}

2.2 新建测试访问类


import com.purgeteam.dynamic.config.starter.event.ActionConfigEvent;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RestController
@Slf4j
@RequestMapping("/api/test2")
public class Test2Controller {//

    @Autowired
    private DemoConfig demoConfig;



    @GetMapping(value = "dd")
    public String test4(String params){

        log.info("dsds" + params);

        System.out.println(demoConfig.getConfig());
        System.out.println(SpringUtil.getApplicationContext().getBean("testController"));
        // 保存数据
        return demoConfig.getConfig();
    }

}

2.3 yml配置

apply:
  demo:
    config: 2225dssww

测试结果：配置中心值改变，对应的属性值也改变

------这里好像没用加@RefreshScope注解

3. 监听到变化触发方法

在监听到配置值变化后，需要触发一些方法，需要实现ApplicationListener<T> 接口，重写onApplicationEvent方法

3.1 触发代码


import com.purgeteam.dynamic.config.starter.event.ActionConfigEvent;
import lombok.extern.slf4j.Slf4j;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.context.ApplicationListener;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.HashMap;
import java.util.Map;

@RestController
@Slf4j
@RequestMapping("/api/test2")
public class Test2Controller implements ApplicationListener<ActionConfigEvent> {//

    @Autowired
    private DemoConfig demoConfig;



    @GetMapping(value = "dd")
    public String test4(String params){

        log.info("dsds" + params);

        System.out.println(demoConfig.getConfig());
        System.out.println(SpringUtil.getApplicationContext().getBean("testController"));
        // 保存数据
        return demoConfig.getConfig();
    }

// 这个方法会在属性变化后调用，这里可以根据某个值变化去处理其他逻辑
    @Override
    public void onApplicationEvent(ActionConfigEvent actionConfigEvent) {
// 获取变化的key
        Map<String, HashMap> propertyMap = actionConfigEvent.getPropertyMap();
// 取出变化的key的map
        HashMap hashMap = propertyMap.get("spring.profiles1.active1");
// 变化后的值
        Object after = hashMap.get("after");
// 变化前的值
        Object after = hashMap.get("before");
// 打印属性值
        log.info("====env========={}",this.demoConfig.getConfig());
    }
}

4. 执行流程分析

处理属性变化绑定值类org.springframework.cloud.context.properties.ConfigurationPropertiesRebinder#onApplicationEvent

自己可以打断点，看方法走向。

获取服务端配置最后是一个string，在com.alibaba.nacos.client.config.impl.ClientWorker.LongPollingRunnable#run这个方法中

String[] ct = ClientWorker.this.getServerConfig(dataId, group, tenant, 3000L);

4.1 服务启动注册配置监听

com.alibaba.cloud.nacos.refresh.NacosContextRefresher#onApplicationEvent这里会调用注册方法com.alibaba.cloud.nacos.refresh.NacosContextRefresher#registerNacosListenersForApplications

// 注册监听方法
private void registerNacosListenersForApplications() {
// 全局开启刷新，默认是true
        if (isRefreshEnabled()) {
            for (NacosPropertySource propertySource : NacosPropertySourceRepository
                    .getAll()) {
            // 判断单个配置文件是否支持刷新，就是refresh = true，开启了就会注册监听，有变化就会及时通知
                if (!propertySource.isRefreshable()) {
                    continue;
                }
                String dataId = propertySource.getDataId();
                // 调用注册方法
                registerNacosListener(propertySource.getGroup(), dataId);
            }
        }
    }

private void registerNacosListener(final String groupKey, final String dataKey) {
        String key = NacosPropertySourceRepository.getMapKey(dataKey, groupKey);
        // 创建监听
        Listener listener = listenerMap.computeIfAbsent(key,
                lst -> new AbstractSharedListener() {
                    @Override
                    public void innerReceive(String dataId, String group,
                            String configInfo) {
                        refreshCountIncrement();
                        nacosRefreshHistory.addRefreshRecord(dataId, group, configInfo);
                        // todo feature: support single refresh for listening
                        applicationContext.publishEvent(
                                new RefreshEvent(this, null, "Refresh Nacos config"));
                        if (log.isDebugEnabled()) {
                            log.debug(String.format(
                                    "Refresh Nacos config group=%s,dataId=%s,configInfo=%s",
                                    group, dataId, configInfo));
                        }
                    }
                });
        try {

        // 这里是最重要的，将监听添加到，config里，注册上
            configService.addListener(dataKey, groupKey, listener);
        }
        catch (NacosException e) {
            log.warn(String.format(
                    "register fail for nacos listener ,dataId=[%s],group=[%s]", dataKey,
                    groupKey), e);
        }
    }

4.2 配置改变刷新配置属性

调用到org.springframework.cloud.context.refresh.ContextRefresher#refreshEnvironment


// 返回变化的key
public synchronized Set<String> refreshEnvironment() {
// 以前的配置的值
        Map<String, Object> before = this.extract(this.context.getEnvironment().getPropertySources());
        this.addConfigFilesToEnvironment();
// 改变后的key
        Set<String> keys = this.changes(before, this.extract(this.context.getEnvironment().getPropertySources())).keySet();

// 发布环境变化时间，spring内部事件
        this.context.publishEvent(new EnvironmentChangeEvent(this.context, keys));
// 返回变化的key
        return keys;
    }

求出以前和现在变化的key

private Map<String, Object> changes(Map<String, Object> before, Map<String, Object> after) {
        Map<String, Object> result = new HashMap();
        Iterator var4 = before.keySet().iterator();

        String key;
        while(var4.hasNext()) {
            key = (String)var4.next();
            if (!after.containsKey(key)) {
                result.put(key, (Object)null);
            } else if (!this.equal(before.get(key), after.get(key))) {
                result.put(key, after.get(key));
            }
        }

        var4 = after.keySet().iterator();

        while(var4.hasNext()) {
            key = (String)var4.next();
            if (!before.containsKey(key)) {
                result.put(key, after.get(key));
            }
        }

        return result;
    }

环境变化事件处理

org.springframework.cloud.context.properties.ConfigurationPropertiesRebinder#onApplicationEvent

public void onApplicationEvent(EnvironmentChangeEvent event) {
        if (this.applicationContext.equals(event.getSource()) || event.getKeys().equals(event.getSource())) {
// 重新绑定值
            this.rebind();
        }

    }

这里会看到需要绑定的配置类

开始绑定

这里绑定值后，虽然经过了销毁和初始化，发现，地址没有变，里面的值变了

刷新后还会调用这个方法org.springframework.cloud.context.refresh.ContextRefresher#refresh

发布一个RefreshScopeRefreshedEvent事件

com.purgeteam.dynamic.config.starter.event.DynamicConfigApplicationListener#onApplicationEvent

public void onApplicationEvent(RefreshEvent event) {
        ConfigurableEnvironment beforeEnv = (ConfigurableEnvironment)this.context.getEnvironment();
        MutablePropertySources propertySources = beforeEnv.getPropertySources();
        MutablePropertySources beforeSources = new MutablePropertySources(propertySources);
        Set<String> refresh = this.refresh.refresh();
        Map<String, HashMap> contrast = this.propertyUtil.contrast(beforeSources, propertySources);

// 发布一个配置变化事件
        this.context.publishEvent(new ActionConfigEvent(this, "Refresh config", contrast));
        log.info("[ActionApplicationListener] The update is successful {}", refresh);
    }

调用到自己的方法

public void onApplicationEvent(ActionConfigEvent actionConfigEvent) {
        Map<String, HashMap> propertyMap = actionConfigEvent.getPropertyMap();
        HashMap hashMap = propertyMap.get("spring.profiles1.active1");
        Object after = hashMap.get("after");
// 触发其他逻辑
        log.info("====env========={}",this.demoConfig.getConfig());
    }