SpringBoot应用篇@Value配置自动刷新能力扩展实践｜ 8月更文挑战

<dependencies>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
</dependencies>
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xhh:
  dynamic:
    name: 一灰灰blog
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spring:
  profiles:
    active: dynamic
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@Data
@Component
public class RefreshConfigProperties {
    @Value("${xhh.dynamic.name}")
    private String name;
    @Value("${xhh.dynamic.age:18}")
    private Integer age;
    @Value("hello ${xhh.dynamic.other:test}")
    private String other;
}
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@Autowired
ConfigurableEnvironment environment;
// --- 配置修改
String name = "applicationConfig: [classpath:/application-dynamic.yml]";
MapPropertySource propertySource = (MapPropertySource) environment.getPropertySources().get(name);
Map<String, Object> source = propertySource.getSource();
Map<String, Object> map = new HashMap<>(source.size());
map.putAll(source);
map.put(key, value);
environment.getPropertySources().replace(name, new MapPropertySource(name, map));
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@Target({ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface RefreshValue {
}
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@Component
public class AnoValueRefreshPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements EnvironmentAware {
    private Map<String, List<FieldPair>> mapper = new HashMap<>();
    private Environment environment;
    @Override
    public boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {
        processMetaValue(bean);
        return super.postProcessAfterInstantiation(bean, beanName);
    }
    /**
     * 这里主要的目的就是获取支持动态刷新的配置属性，然后缓存起来
     *
     * @param bean
     */
    private void processMetaValue(Object bean) {
        Class clz = bean.getClass();
        if (!clz.isAnnotationPresent(RefreshValue.class)) {
            return;
        }
        try {
            for (Field field : clz.getDeclaredFields()) {
                if (field.isAnnotationPresent(Value.class)) {
                    Value val = field.getAnnotation(Value.class);
                    List<String> keyList = pickPropertyKey(val.value(), 0);
                    for (String key : keyList) {
                        mapper.computeIfAbsent(key, (k) -> new ArrayList<>())
                                .add(new FieldPair(bean, field, val.value()));
                    }
                }
            }
        } catch (Exception e) {
            e.printStackTrace();
            System.exit(-1);
        }
    }
    /**
     * 实现一个基础的配置文件参数动态刷新支持
     *
     * @param value
     * @return 提取key列表
     */
    private List<String> pickPropertyKey(String value, int begin) {
        int start = value.indexOf("${", begin) + 2;
        if (start < 2) {
            return new ArrayList<>();
        }
        int middle = value.indexOf(":", start);
        int end = value.indexOf("}", start);
        String key;
        if (middle > 0 && middle < end) {
            // 包含默认值
            key = value.substring(start, middle);
        } else {
            // 不包含默认值
            key = value.substring(start, end);
        }
        List<String> keys = pickPropertyKey(value, end);
        keys.add(key);
        return keys;
    }
    @Override
    public void setEnvironment(Environment environment) {
        this.environment = environment;
    }
    @Data
    @NoArgsConstructor
    @AllArgsConstructor
    public static class FieldPair {
        private static PropertyPlaceholderHelper propertyPlaceholderHelper = new PropertyPlaceholderHelper("${", "}",
                ":", true);
        Object bean;
        Field field;
        String value;
        public void updateValue(Environment environment) {
            boolean access = field.isAccessible();
            if (!access) {
                field.setAccessible(true);
            }
            String updateVal = propertyPlaceholderHelper.replacePlaceholders(value, environment::getProperty);
            try {
                if (field.getType() == String.class) {
                    field.set(bean, updateVal);
                } else {
                    field.set(bean, JSONObject.parseObject(updateVal, field.getType()));
                }
            } catch (IllegalAccessException e) {
                e.printStackTrace();
            }
            field.setAccessible(access);
        }
    }
}
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public static class ConfigUpdateEvent extends ApplicationEvent {
    String key;
    public ConfigUpdateEvent(Object source, String key) {
        super(source);
        this.key = key;
    }
}
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@EventListener
public void updateConfig(ConfigUpdateEvent configUpdateEvent) {
    List<FieldPair> list = mapper.get(configUpdateEvent.key);
    if (!CollectionUtils.isEmpty(list)) {
        list.forEach(f -> f.updateValue(environment));
    }
}
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@RestController
public class DynamicRest {
    @Autowired
    ApplicationContext applicationContext;
    @Autowired
    ConfigurableEnvironment environment;
    @Autowired
    RefreshConfigProperties refreshConfigProperties;
    @GetMapping(path = "dynamic/update")
    public RefreshConfigProperties updateEnvironment(String key, String value) {
        String name = "applicationConfig: [classpath:/application-dynamic.yml]";
        MapPropertySource propertySource = (MapPropertySource) environment.getPropertySources().get(name);
        Map<String, Object> source = propertySource.getSource();
        Map<String, Object> map = new HashMap<>(source.size());
        map.putAll(source);
        map.put(key, value);
        environment.getPropertySources().replace(name, new MapPropertySource(name, map));
        applicationContext.publishEvent(new AnoValueRefreshPostProcessor.ConfigUpdateEvent(this, key));
        return refreshConfigProperties;
    }
}
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