前言

在系统运行过程中，可能由于一些配置项的简单变动需要重新打包启停项目，这对于在运行中的项目会造成数据丢失，客户操作无响应等情况发生，针对这类情况对开发框架进行升级提供yml文件实时修改更新功能

项目依赖

项目基于的是2.0.0.RELEASE版本，所以snakeyaml需要单独引入，高版本已包含在内

        org.yamlsnakeyaml1.23

网上大多数方法是引入spring-cloud-context配置组件调用ContextRefresher的refresh方法达到同样的效果，考虑以下两点未使用

• 开发框架使用了logback日志，引入spring-cloud-context会造成日志配置读取错误
• 引入spring-cloud-context会同时引入spring-boot-starter-actuator组件，会开放一些健康检查路由及端口，需要对框架安全方面进行额外控制

YML文件内容获取

读取resource文件下的文件需要使用ClassPathResource获取InputStream

    public String getTotalYamlFileContent() throws Exception {String fileName = "application.yml";return getYamlFileContent(fileName);}public String getYamlFileContent(String fileName) throws Exception {ClassPathResource classPathResource = new ClassPathResource(fileName);return onvertStreamToString(classPathResource.getInputStream());}public static String convertStreamToString(InputStream inputStream) throws Exception{return IOUtils.toString(inputStream, "utf-8");}

YML文件内容更新

我们获取到yml文件内容后可视化显示到前台进行展示修改，将修改后的内容通过yaml.load方法转换成Map结构，再使用yaml.dumpAsMap转换为流写入到文件

    public void updateTotalYamlFileContent(String content) throws Exception {String fileName = "application.yml";updateYamlFileContent(fileName, content);}public void updateYamlFileContent(String fileName, String content) throws Exception {Yaml template = new Yaml();Map yamlMap = template.load(content);ClassPathResource classPathResource = new ClassPathResource(fileName);Yaml yaml = new Yaml();//字符输出FileWriter fileWriter = new FileWriter(classPathResource.getFile());//用yaml方法把map结构格式化为yaml文件结构fileWriter.write(yaml.dumpAsMap(yamlMap));//刷新fileWriter.flush();//关闭流fileWriter.close();}

YML属性刷新

yml属性在程序中读取使用一般有三种

• 使用Value注解

    @Value("${system.systemName}")private String systemName;

• 通过enviroment注入读取

    @Autowiredprivate Environment environment;environment.getProperty("system.systemName")

• 使用ConfigurationProperties注解读取

@Component
@ConfigurationProperties(prefix = "system")
public class SystemConfig {private String systemName;
}

Property刷新

我们通过environment.getProperty方法读取的配置集合实际是存储在PropertySources中的，我们只需要把键值对全部取出存储在propertyMap中，将更新后的yml文件内容转换成相同格式的ymlMap，两个Map进行合并，调用PropertySources的replace方法进行整体替换即可

但是yaml.load后的ymlMap和PropertySources取出的propertyMap两者数据解构是不同的，需要进行手动转换

propertyMap集合就是单纯的key，value键值对，key是properties形式的名称，例如system.systemName=>xxxxx集团管理系统

ymlMap集合是key，LinkedHashMap的嵌套层次结构，例如system=>(systemName=>xxxxx集团管理系统)

• 转换方法如下

  public HashMap convertYmlMapToPropertyMap(Map yamlMap) {HashMap propertyMap = new HashMap();for (String key : yamlMap.keySet()) {String keyName = key;Object value = yamlMap.get(key);if (value != null && value.getClass() == LinkedHashMap.class) {convertYmlMapToPropertyMapSub(keyName, ((LinkedHashMap) value), propertyMap);} else {propertyMap.put(keyName, value);}}return propertyMap;}private void convertYmlMapToPropertyMapSub(String keyName, LinkedHashMap submMap, Map propertyMap) {for (String key : submMap.keySet()) {String newKey = keyName + "." + key;Object value = submMap.get(key);if (value != null && value.getClass() == LinkedHashMap.class) {convertYmlMapToPropertyMapSub(newKey, ((LinkedHashMap) value), propertyMap);} else {propertyMap.put(newKey, value);}}}

• 刷新方法如下

        String name = "applicationConfig: [classpath:/" + fileName + "]";MapPropertySource propertySource = (MapPropertySource) environment.getPropertySources().get(name);Map source = propertySource.getSource();Map map = new HashMap<>(source.size());map.putAll(source);Map propertyMap = convertYmlMapToPropertyMap(yamlMap);for (String key : propertyMap.keySet()) {Object value = propertyMap.get(key);map.put(key, value);}environment.getPropertySources().replace(name, new MapPropertySource(name, map));

注解刷新

不论是Value注解还是ConfigurationProperties注解，实际都是通过注入Bean对象的属性方法使用的，我们先自定注解RefreshValue来修饰属性所在Bean的class

通过实现InstantiationAwareBeanPostProcessorAdapter接口在系统启动时过滤筛选对应的Bean存储下来，在更新yml文件时通过spring的event通知更新对应

bean的属性即可

• 注册事件使用EventListener注解

    @EventListenerpublic void updateConfig(ConfigUpdateEvent configUpdateEvent) {if(mapper.containsKey(configUpdateEvent.key)){List fieldPairList = mapper.get(configUpdateEvent.key);if(fieldPairList.size()>0){for (FieldPair fieldPair:fieldPairList) {fieldPair.updateValue(environment);}}}}

• 通知触发事件使用ApplicationContext的publishEvent方法

    @Autowiredprivate ApplicationContext applicationContext;for (String key : propertyMap.keySet()) {applicationContext.publishEvent(new YamlConfigRefreshPostProcessor.ConfigUpdateEvent(this, key));}

YamlConfigRefreshPostProcessor的完整代码如下

@Component
public class YamlConfigRefreshPostProcessor extends InstantiationAwareBeanPostProcessorAdapter implements EnvironmentAware {private Map> mapper = new HashMap<>();private Environment environment;@Overridepublic boolean postProcessAfterInstantiation(Object bean, String beanName) throws BeansException {processMetaValue(bean);return super.postProcessAfterInstantiation(bean, beanName);}@Overridepublic void setEnvironment(Environment environment) {this.environment = environment;}private void processMetaValue(Object bean) {Class clz = bean.getClass();if (!clz.isAnnotationPresent(RefreshValue.class)) {return;}if (clz.isAnnotationPresent(ConfigurationProperties.class)) {//@ConfigurationProperties注解ConfigurationProperties config = (ConfigurationProperties) clz.getAnnotation(ConfigurationProperties.class);for (Field field : clz.getDeclaredFields()) {String key = config.prefix() + "." + field.getName();if(mapper.containsKey(key)){mapper.get(key).add(new FieldPair(bean, field, key));}else{List fieldPairList = new ArrayList<>();fieldPairList.add(new FieldPair(bean, field, key));mapper.put(key, fieldPairList);}}} else {//@Valuez注解try {for (Field field : clz.getDeclaredFields()) {if (field.isAnnotationPresent(Value.class)) {Value val = field.getAnnotation(Value.class);String key = val.value().replace("${", "").replace("}", "");if(mapper.containsKey(key)){mapper.get(key).add(new FieldPair(bean, field, key));}else{List fieldPairList = new ArrayList<>();fieldPairList.add(new FieldPair(bean, field, key));mapper.put(key, fieldPairList);}}}} catch (Exception e) {e.printStackTrace();System.exit(-1);}}}public static class FieldPair {private static PropertyPlaceholderHelper propertyPlaceholderHelper = new PropertyPlaceholderHelper("${", "}",":", true);private Object bean;private Field field;private String value;public FieldPair(Object bean, Field field, String value) {this.bean = bean;this.field = field;this.value = value;}public void updateValue(Environment environment) {boolean access = field.isAccessible();if (!access) {field.setAccessible(true);}try {if (field.getType() == String.class) {String updateVal = environment.getProperty(value);field.set(bean, updateVal);}else if (field.getType() == Integer.class) {Integer updateVal = environment.getProperty(value,Integer.class);field.set(bean, updateVal);}else if (field.getType() == int.class) {int updateVal = environment.getProperty(value,int.class);field.set(bean, updateVal);}else if (field.getType() == Boolean.class) {Boolean updateVal = environment.getProperty(value,Boolean.class);field.set(bean, updateVal);}else if (field.getType() == boolean.class) {boolean updateVal = environment.getProperty(value,boolean.class);field.set(bean, updateVal);}else {String updateVal = environment.getProperty(value);field.set(bean, JSONObject.parseObject(updateVal, field.getType()));}} catch (IllegalAccessException e) {e.printStackTrace();}field.setAccessible(access);}public Object getBean() {return bean;}public void setBean(Object bean) {this.bean = bean;}public Field getField() {return field;}public void setField(Field field) {this.field = field;}public String getValue() {return value;}public void setValue(String value) {this.value = value;}}public static class ConfigUpdateEvent extends ApplicationEvent {String key;public ConfigUpdateEvent(Object source, String key) {super(source);this.key = key;}}@EventListenerpublic void updateConfig(ConfigUpdateEvent configUpdateEvent) {if(mapper.containsKey(configUpdateEvent.key)){List fieldPairList = mapper.get(configUpdateEvent.key);if(fieldPairList.size()>0){for (FieldPair fieldPair:fieldPairList) {fieldPair.updateValue(environment);}}}}
}