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

        <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);                }            }        }    }}