标签：add extend getc etc comment alt lis ppi obj
需求描述：在SpringBoot项目中，一般业务配置都是写死在配置文件中的，如果某个业务配置想修改，就得重启项目。这在生产环境是不被允许的，这就需要通过技术手段做到配置变更后即使生效。下面就来看一下怎么实现这个功能。
来一张核心代码截图：
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实现思路：
我们知道Spring提供了@Value注解来获取配置文件中的配置项，我们也可以自己定义一个注解来模仿Spring的这种获取配置的方式，
只不过@Value获取的是静态的配置，而我们的注解要实现配置能实时刷新。比如我使用@DynamicConf("${key}")来引用配置，在SpringBoot工程启动的时候，
就扫描项目中所有使用了该注解的Bean属性，将配置信息从数据库中读取出来放到本地缓存，然后挨个赋值给加了@DynamicConf注解的属性。
当配置有变更时，就动态给这个属性重新赋值。这就是最核心的思路，下面看如何用代码实现。
1.创建一张数据表，用于存储配置信息：
CREATE TABLE `s_system_dict` ( `id` int(11) NOT NULL AUTO_INCREMENT COMMENT ‘自增主键，唯一标识‘, `dict_name` varchar(64) NOT NULL COMMENT ‘字典名称‘, `dict_key` varchar(255) NOT NULL COMMENT ‘字典KEY‘, `dict_value` varchar(2000) NOT NULL COMMENT ‘字典VALUE‘, `dict_type` int(11) NOT NULL DEFAULT ‘0‘ COMMENT ‘字典类型 0系统配置 1微信配置 2支付宝配置 3推送 4短信 5版本‘, `dict_desc` varchar(255) NOT NULL DEFAULT ‘‘ COMMENT ‘字典描述‘, `status` int(4) NOT NULL DEFAULT ‘1‘ COMMENT ‘字典状态：0-停用 1-正常‘, `delete_flag` tinyint(1) NOT NULL DEFAULT ‘0‘ COMMENT ‘是否删除：0-未删除 1-已删除‘, `operator` int(11) NOT NULL COMMENT ‘操作人ID，关联用户域用户表ID‘, `create_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT ‘创建时间‘, `update_time` datetime NOT NULL DEFAULT CURRENT_TIMESTAMP COMMENT ‘修改时间‘, `delete_time` datetime NOT NULL DEFAULT ‘1970-01-01 00:00:00‘ COMMENT ‘删除时间‘, PRIMARY KEY (`id`) ) ENGINE=InnoDB AUTO_INCREMENT=47 DEFAULT CHARSET=utf8 COMMENT=‘配置字典表‘;
2.自定义注解
import java.lang.annotation.*; @Target(ElementType.FIELD) @Retention(RetentionPolicy.RUNTIME) @Documented public @interface DynamicConf { String value(); String defaultValue() default ""; boolean callback() default true; }
3.配置变更接口
public interface DynamicConfListener { void onChange(String key, String value) throws Exception; }
4.配置变更实现：
public class BeanRefreshDynamicConfListener implements DynamicConfListener { public static class BeanField { private String beanName; private String property; public BeanField() { } public BeanField(String beanName, String property) { this.beanName = beanName; this.property = property; } public String getBeanName() { return beanName; } public void setBeanName(String beanName) { this.beanName = beanName; } public String getProperty() { return property; } public void setProperty(String property) { this.property = property; } } private static Map<String, List<BeanField>> key2BeanField = new ConcurrentHashMap<>(); public static void addBeanField(String key, BeanField beanField) { List<BeanField> beanFieldList = key2BeanField.get(key); if (beanFieldList == null) { beanFieldList = new ArrayList<>(); key2BeanField.put(key, beanFieldList); } for (BeanField item : beanFieldList) { if (item.getBeanName().equals(beanField.getBeanName()) && item.getProperty().equals(beanField.getProperty())) { return; // avoid repeat refresh } } beanFieldList.add(beanField); } /** * refresh bean field * * @param key * @param value * @throws Exception */ @Override public void onChange(String key, String value) throws Exception { List<BeanField> beanFieldList = key2BeanField.get(key); if (beanFieldList != null && beanFieldList.size() > 0) { for (BeanField beanField : beanFieldList) { DynamicConfFactory.refreshBeanField(beanField, value, null); } } } }
5.用一个工程包装一下
public class DynamicConfListenerFactory { /** * dynamic config listener repository */ private static List<DynamicConfListener> confListenerRepository = Collections.synchronizedList(new ArrayList<>()); /** * add listener * * @param confListener * @return */ public static boolean addListener(DynamicConfListener confListener) { if (confListener == null) { return false; } confListenerRepository.add(confListener); return true; } /** * refresh bean field * * @param key * @param value */ public static void onChange(String key, String value) { if (key == null || key.trim().length() == 0) { return; } if (confListenerRepository.size() > 0) { for (DynamicConfListener confListener : confListenerRepository) { try { confListener.onChange(key, value); } catch (Exception e) { log.error(">>>>>>>>>>> refresh bean field, key={}, value={}, exception={}", key, value, e); } } } } }
6.对Spring的扩展，实现实时刷新功能最核心的部分
public class DynamicConfFactory extends InstantiationAwareBeanPostProcessorAdapter implements InitializingBean, DisposableBean, BeanNameAware, BeanFactoryAware {
// 注入操作配置信息的业务类 @Autowired private SystemDictService systemDictService; @Override public void afterPropertiesSet() { DynamicConfBaseFactory.init();
// 启动时将数据库中的配置缓存到本地（用一个Map存） LocalDictMap.setDictMap(systemDictService.all()); } @Override public void destroy() { DynamicConfBaseFactory.destroy(); } @Override public boolean postProcessAfterInstantiation(final Object bean, final String beanName) throws BeansException { if (!beanName.equals(this.beanName)) { ReflectionUtils.doWithFields(bean.getClass(), field -> { if (field.isAnnotationPresent(DynamicConf.class)) { String propertyName = field.getName(); DynamicConf dynamicConf = field.getAnnotation(DynamicConf.class); String confKey = dynamicConf.value(); confKey = confKeyParse(confKey);
// 从本地缓存中获取配置 String confValue = LocalDictMap.getDict(confKey); confValue = !StringUtils.isEmpty(confValue) ? confValue : ""; BeanRefreshDynamicConfListener.BeanField beanField = new BeanRefreshDynamicConfListener.BeanField(beanName, propertyName); refreshBeanField(beanField, confValue, bean); if (dynamicConf.callback()) { BeanRefreshDynamicConfListener.addBeanField(confKey, beanField); } } }); } return super.postProcessAfterInstantiation(bean, beanName); } public static void refreshBeanField(final BeanRefreshDynamicConfListener.BeanField beanField, final String value, Object bean) { if (bean == null) { try {
// 如果你的项目使用了Aop，比如AspectJ，那么有些Bean可能会被代理，
// 这里你获取到的可能就不是真实的Bean而是被代理后的Bean，所以这里获取真实的Bean; bean = AopTargetUtils.getTarget(DynamicConfFactory.beanFactory.getBean(beanField.getBeanName())); } catch (Exception e) { log.error(">>>>>>>>>>>> Get target bean fail!!!!!"); } } if (bean == null) { return; } BeanWrapper beanWrapper = new BeanWrapperImpl(bean); PropertyDescriptor propertyDescriptor = null; PropertyDescriptor[] propertyDescriptors = beanWrapper.getPropertyDescriptors(); if (propertyDescriptors != null && propertyDescriptors.length > 0) { for (PropertyDescriptor item : propertyDescriptors) { if (beanField.getProperty().equals(item.getName())) { propertyDescriptor = item; } } } if (propertyDescriptor != null && propertyDescriptor.getWriteMethod() != null) { beanWrapper.setPropertyValue(beanField.getProperty(), value); log.info(">>>>>>>>>>> refresh bean field[set] success, {}#{}={}", beanField.getBeanName(), beanField.getProperty(), value); } else { final Object finalBean = bean; ReflectionUtils.doWithFields(bean.getClass(), fieldItem -> { if (beanField.getProperty().equals(fieldItem.getName())) { try { Object valueObj = FieldReflectionUtil.parseValue(fieldItem.getType(), value); fieldItem.setAccessible(true); fieldItem.set(finalBean, valueObj); log.info(">>>>>>>>>>> refresh bean field[field] success, {}#{}={}", beanField.getBeanName(), beanField.getProperty(), value); } catch (IllegalAccessException e) { throw new RuntimeException(">>>>>>>>>>> refresh bean field[field] fail, " + beanField.getBeanName() + "#" + beanField.getProperty() + "=" + value); } } }); } } private static final String placeholderPrefix = "${"; private static final String placeholderSuffix = "}"; /** * valid placeholder * * @param originKey * @return */ private static boolean confKeyValid(String originKey) { if (originKey == null || "".equals(originKey.trim())) { throw new RuntimeException(">>>>>>>>>>> originKey[" + originKey + "] not be empty"); } boolean start = originKey.startsWith(placeholderPrefix); boolean end = originKey.endsWith(placeholderSuffix); return start && end ? true : false; } /** * parse placeholder * * @param originKey * @return */ private static String confKeyParse(String originKey) { if (confKeyValid(originKey)) { return originKey.substring(placeholderPrefix.length(), originKey.length() - placeholderSuffix.length()); } return originKey; } private String beanName; @Override public void setBeanName(String name) { this.beanName = name; } private static BeanFactory beanFactory; @Override public void setBeanFactory(BeanFactory beanFactory) throws BeansException { this.beanFactory = beanFactory; } }
7.配置Bean
@Configuration public class DynamicConfConfig { @Bean public DynamicConfFactory dynamicConfFactory() { DynamicConfFactory dynamicConfFactory = new DynamicConfFactory(); return dynamicConfFactory; } }
8.使用方式
@RestController @RequestMapping("/test") public class TestController { @DynamicConf("${test.dynamic.config.key}") private String testDynamicConfig; @GetMapping("/getConfig") public JSONObject testDynamicConfig(String key) {
// 从本地缓存获取配置(就是一个Map) String value = LocalDictMap.getDict(key); JSONObject json = new JSONObject(); json.put(key, value); return json; }
// 通过接口来修改数据库中的配置信息 @GetMapping("/updateConfig") public String updateConfig(String key, String value) { SystemDictDto dictDto = new SystemDictDto(); dictDto.setDictKey(key); dictDto.setDictValue(value); systemDictService.update(dictDto, 0); return "success"; } }
9.配置变更后刷新
// 刷新Bean属性
DynamicConfListenerFactory.onChange(dictKey, dictValue);
// TODO 刷新本地缓存 略
10.补上一个工具类）
public class AopTargetUtils { /** * 获取目标对象 * * @param proxy 代理对象 * @return 目标对象 * @throws Exception */ public static Object getTarget(Object proxy) throws Exception { if (!AopUtils.isAopProxy(proxy)) { return proxy; } if (AopUtils.isJdkDynamicProxy(proxy)) { proxy = getJdkDynamicProxyTargetObject(proxy); } else { proxy = getCglibProxyTargetObject(proxy); } return getTarget(proxy); } private static Object getCglibProxyTargetObject(Object proxy) throws Exception { Field h = proxy.getClass().getDeclaredField("CGLIB$CALLBACK_0"); h.setAccessible(true); Object dynamicAdvisedInterceptor = h.get(proxy); Field advised = dynamicAdvisedInterceptor.getClass().getDeclaredField("advised"); advised.setAccessible(true); Object target = ((AdvisedSupport) advised.get(dynamicAdvisedInterceptor)).getTargetSource().getTarget(); return target; } private static Object getJdkDynamicProxyTargetObject(Object proxy) throws Exception { Field h = proxy.getClass().getSuperclass().getDeclaredField("h"); h.setAccessible(true); AopProxy aopProxy = (AopProxy) h.get(proxy); Field advised = aopProxy.getClass().getDeclaredField("advised"); advised.setAccessible(true); Object target = ((AdvisedSupport) advised.get(aopProxy)).getTargetSource().getTarget(); return target; } }
标签：add extend getc etc comment alt lis ppi obj
原文地址：https://www.cnblogs.com/jun1019/p/11367639.html
