Spring的MapPropertySource刷新系统属性值（key-value配置在外部系统中如redis，数据库等)

我们经常会把一些属性值以key=value的形式放在properties文件中，有的时候，我们可能会将一些经常变动的属性值放在外部系统中，比如redis或者数据库中，如果在某个时刻修改了redis中的值，如何让使用了该值的系统及时刷新系统内存中的值呢？下面我将介绍，如何在Spring环境中动态刷新属性值。

1、假设我在redis服务器上set了一个key为env,value为dev的值

2、自定义MapPropertySource并继承Spring的MapPropertySource类，在自定义的刷新类中添加refresh方法，用于定时刷新内部属性值

package com.example.spring.refresh.config;import com.google.common.collect.Maps;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.boot.autoconfigure.AutoConfigureAfter;import org.springframework.core.env.MapPropertySource;import org.springframework.data.redis.core.RedisTemplate;import org.springframework.data.redis.core.StringRedisTemplate;import org.springframework.stereotype.Component;import javax.annotation.PostConstruct;import java.util.Map;/** * ClassName: RefreshPropertySource <br/> * Description: 将外部属性，在实例化时动态注入到Spring容器中 <br/> * Date: 2017/10/12 13:56 <br/> * * @author sxp([e-mail]) <br/> * @version 1.0 <br/> */@Component@AutoConfigureAfter(RedisTemplate.class)public class RefreshPropertySource extends MapPropertySource {    @Autowired    private StringRedisTemplate redisTemplate;    public RefreshPropertySource(String name, Map<String, Object> source) {        super(name, source);    }    public RefreshPropertySource() {        super("RefreshPropertySource", Maps.newHashMap());    }    @PostConstruct    public void setup() {        redisTemplate.opsForValue().set("env", "dev");    }    public void refresh() {        String env = redisTemplate.opsForValue().get("env");        this.source.put("env", env);    }}

3、使用Spring的定时器机制，定时检测外部系统中属性值的变化

package com.example.spring.refresh.config;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.cloud.context.refresh.ContextRefresher;import org.springframework.cloud.context.scope.refresh.RefreshScope;import org.springframework.core.env.ConfigurableEnvironment;import org.springframework.scheduling.annotation.Scheduled;import org.springframework.stereotype.Component;import org.springframework.web.client.RestTemplate;/** * ClassName: RefreshScheduler <br/> * Description: RefreshScheduler <br/> * Date: 2017/10/11 10:22 <br/> * * @author sxp([e-mail]) <br/> * @version 1.0 <br/> */@Componentpublic class RefreshScheduler {    @Autowired    private ConfigurableEnvironment environment;    @Autowired    private RefreshPropertySource refreshPropertySource;    @PostConstruct    public void setup() {        environment.getPropertySources().addLast(refreshPropertySource);    }    @Scheduled(cron = "*/5 * * * * ?")    public void scheduling() {        /* 将自定的RefreshPropertySource添加到Spring的环境中定时刷新 */        environment.getPropertySources().addLast(refreshPropertySource);        System.out.println(environment.getProperty("env"));    }}