这篇文章主要介绍“SpringBoot怎么动态更新yml文件”的相关知识，小编通过实际案例向大家展示操作过程，操作方法简单快捷，实用性强，希望这篇“SpringBoot怎么动态更新yml文件”文章能帮助大家解决问题。
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
<dependency> <groupId>org.yaml</groupId> <artifactId>snakeyaml</artifactId> <version>1.23</version> </dependency>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<String, Object> 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
@Autowired private 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<String, Object> convertYmlMapToPropertyMap(Map<String, Object> yamlMap) { HashMap<String, Object> propertyMap = new HashMap<String, Object>(); for (String key : yamlMap.keySet()) { String keyName = key; Object value = yamlMap.get(key); if (value != null && value.getClass() == LinkedHashMap.class) { convertYmlMapToPropertyMapSub(keyName, ((LinkedHashMap<String, Object>) value), propertyMap); } else { propertyMap.put(keyName, value); } } return propertyMap; } private void convertYmlMapToPropertyMapSub(String keyName, LinkedHashMap<String, Object> submMap, Map<String, Object> 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<String, Object>) 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<String, Object> source = propertySource.getSource(); Map<String, Object> map = new HashMap<>(source.size()); map.putAll(source); Map<String, Object> 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
@EventListener public void updateConfig(ConfigUpdateEvent configUpdateEvent) { if(mapper.containsKey(configUpdateEvent.key)){ List<FieldPair> 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
@Autowired private ApplicationContext applicationContext; for (String key : propertyMap.keySet()) { applicationContext.publishEvent(new YamlConfigRefreshPostProcessor.ConfigUpdateEvent(this, key)); }YamlConfigRefreshPostProcessor的完整代码如下
@Componentpublic class YamlConfigRefreshPostProcessor 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); } @Override public 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<FieldPair> 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<FieldPair> 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; } } @EventListener public void updateConfig(ConfigUpdateEvent configUpdateEvent) { if(mapper.containsKey(configUpdateEvent.key)){ List<FieldPair> fieldPairList = mapper.get(configUpdateEvent.key); if(fieldPairList.size()>0){ for (FieldPair fieldPair:fieldPairList) { fieldPair.updateValue(environment); } } } }}关于“SpringBoot怎么动态更新yml文件”的内容就介绍到这里了，感谢大家的阅读。如果想了解更多行业相关的知识，可以关注编程网行业资讯频道，小编每天都会为大家更新不同的知识点。
