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SpringBoot动态更新yml文件

作者：code2roc　　发布时间：2022-02-23 00:34:23　

标签：SpringBoot,动态,更新,yml

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

@Component
public 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);
}
}
}
}
}

来源：https://blog.csdn.net/u013407099/article/details/128507905

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