AmyliaY
5 years ago
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GitHub
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19a762e93a
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# Mybatis MetaObject
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读工程: [huifer-mybatis](https://github.com/huifer/javaBook-src/tree/old/mybatis-3)
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- 源码位于:`org.apache.ibatis.reflection.MetaObject`
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```java
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/**
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* @author Clinton Begin
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*/
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public class MetaObject {
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/**
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* 原始的数据对象,初始化时的对象
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*/
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private final Object originalObject;
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/**
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* 对象包装
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*/
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private final ObjectWrapper objectWrapper;
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/**
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* object 工厂
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*/
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private final ObjectFactory objectFactory;
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/**
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* object
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*/
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private final ObjectWrapperFactory objectWrapperFactory;
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/**
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* 反射工程
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*/
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private final ReflectorFactory reflectorFactory;
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private MetaObject(Object object, ObjectFactory objectFactory, ObjectWrapperFactory objectWrapperFactory, ReflectorFactory reflectorFactory) {
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this.originalObject = object;
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this.objectFactory = objectFactory;
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this.objectWrapperFactory = objectWrapperFactory;
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this.reflectorFactory = reflectorFactory;
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// 根据object不同实例进行不同的实例化方式
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if (object instanceof ObjectWrapper) {
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this.objectWrapper = (ObjectWrapper) object;
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} else if (objectWrapperFactory.hasWrapperFor(object)) {
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this.objectWrapper = objectWrapperFactory.getWrapperFor(this, object);
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} else if (object instanceof Map) {
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this.objectWrapper = new MapWrapper(this, (Map) object);
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} else if (object instanceof Collection) {
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this.objectWrapper = new CollectionWrapper(this, (Collection) object);
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} else {
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this.objectWrapper = new BeanWrapper(this, object);
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}
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}
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public static MetaObject forObject(Object object, ObjectFactory objectFactory, ObjectWrapperFactory objectWrapperFactory, ReflectorFactory reflectorFactory) {
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if (object == null) {
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return SystemMetaObject.NULL_META_OBJECT;
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} else {
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return new MetaObject(object, objectFactory, objectWrapperFactory, reflectorFactory);
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}
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}
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/**
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* 获取value
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* @param name 属性值名称
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* @return
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*/
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public Object getValue(String name) {
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PropertyTokenizer prop = new PropertyTokenizer(name);
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if (prop.hasNext()) {
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MetaObject metaValue = metaObjectForProperty(prop.getIndexedName());
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if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
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// 判断是否是空的metaObject
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return null;
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} else {
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return metaValue.getValue(prop.getChildren());
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}
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} else {
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return objectWrapper.get(prop);
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}
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}
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/**
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* metaObject 设置属性值方法
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* {name:value}
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*
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* @param name 属性值名称
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* @param value 属性值
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*/
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public void setValue(String name, Object value) {
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PropertyTokenizer prop = new PropertyTokenizer(name);
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if (prop.hasNext()) {
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// 获取属性实例
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MetaObject metaValue = metaObjectForProperty(prop.getIndexedName());
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if (metaValue == SystemMetaObject.NULL_META_OBJECT) {
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if (value == null) {
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// value 空则返回
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// don't instantiate child path if value is null
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return;
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} else {
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// 创建属性值
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metaValue = objectWrapper.instantiatePropertyValue(name, prop, objectFactory);
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}
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}
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metaValue.setValue(prop.getChildren(), value);
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} else {
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objectWrapper.set(prop, value);
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}
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}
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}
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```
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@ -0,0 +1,158 @@
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# EntityResolver
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [huifer-spring](https://github.com/huifer/spring-framework)
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- 源码路径: `org.xml.sax.EntityResolver`,非Spring类
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## DelegatingEntityResolver#resolveEntity
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- org.springframework.beans.factory.xml.DelegatingEntityResolver.resolveEntity
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```java
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@Override
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@Nullable
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public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId)
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throws SAXException, IOException {
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if (systemId != null) {
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if (systemId.endsWith(DTD_SUFFIX)) {
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return this.dtdResolver.resolveEntity(publicId, systemId);
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}
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else if (systemId.endsWith(XSD_SUFFIX)) {
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return this.schemaResolver.resolveEntity(publicId, systemId);
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}
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}
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// Fall back to the parser's default behavior.
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return null;
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}
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```
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- 上述这段代码是针对xml进行校验
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```xml
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<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xmlns="http://www.springframework.org/schema/beans"
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xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
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```
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- 如上所示以`.xsd`结尾,应该执行` return this.schemaResolver.resolveEntity(publicId, systemId);`方法
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`http://www.springframework.org/schema/beans/spring-beans.xsd`
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- `org.springframework.beans.factory.xml.PluggableSchemaResolver.resolveEntity`
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## PluggableSchemaResolver#resolveEntity
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```java
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@Override
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@Nullable
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public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId) throws IOException {
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if (logger.isTraceEnabled()) {
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logger.trace("Trying to resolve XML entity with public id [" + publicId +
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"] and system id [" + systemId + "]");
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}
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if (systemId != null) {
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// 获取当前 systemId 对应的资源
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// spring-framework\spring-beans\src\main\resources\org\springframework\beans\factory\xml\spring-beans.xsd
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String resourceLocation = getSchemaMappings().get(systemId);
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if (resourceLocation == null && systemId.startsWith("https:")) {
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// Retrieve canonical http schema mapping even for https declaration
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resourceLocation = getSchemaMappings().get("http:" + systemId.substring(6));
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}
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if (resourceLocation != null) {
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// 加载 resourceLocation 转换成 Resource
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Resource resource = new ClassPathResource(resourceLocation, this.classLoader);
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try {
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// 读取
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InputSource source = new InputSource(resource.getInputStream());
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source.setPublicId(publicId);
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source.setSystemId(systemId);
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if (logger.isTraceEnabled()) {
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logger.trace("Found XML schema [" + systemId + "] in classpath: " + resourceLocation);
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}
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return source;
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}
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catch (FileNotFoundException ex) {
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if (logger.isDebugEnabled()) {
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logger.debug("Could not find XML schema [" + systemId + "]: " + resource, ex);
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}
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}
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}
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}
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// Fall back to the parser's default behavior.
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return null;
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}
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```
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得到本地路径，后续直接返回读取资源
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## BeansDtdResolver#resolveEntity
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创建一个Dtd的约束文件
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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<beans xmlns="http://www.springframework.org/schema/beans"
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xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
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xsi:schemaLocation="http://www.springframework.org/schema/beans https://www.springframework.org/dtd/spring-beans-2.0.dtd">
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</beans>
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```
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```java
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@Override
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@Nullable
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public InputSource resolveEntity(@Nullable String publicId, @Nullable String systemId) throws IOException {
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if (logger.isTraceEnabled()) {
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logger.trace("Trying to resolve XML entity with public ID [" + publicId +
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"] and system ID [" + systemId + "]");
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}
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if (systemId != null && systemId.endsWith(DTD_EXTENSION)) {
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int lastPathSeparator = systemId.lastIndexOf('/');
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int dtdNameStart = systemId.indexOf(DTD_NAME, lastPathSeparator);
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if (dtdNameStart != -1) {
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// 获取静态变量组装成文件名称(spring-beans.dtd)
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String dtdFile = DTD_NAME + DTD_EXTENSION;
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if (logger.isTraceEnabled()) {
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logger.trace("Trying to locate [" + dtdFile + "] in Spring jar on classpath");
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}
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try {
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// 加载资源
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Resource resource = new ClassPathResource(dtdFile, getClass());
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InputSource source = new InputSource(resource.getInputStream());
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source.setPublicId(publicId);
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source.setSystemId(systemId);
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if (logger.isTraceEnabled()) {
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logger.trace("Found beans DTD [" + systemId + "] in classpath: " + dtdFile);
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}
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return source;
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}
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catch (FileNotFoundException ex) {
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if (logger.isDebugEnabled()) {
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logger.debug("Could not resolve beans DTD [" + systemId + "]: not found in classpath", ex);
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}
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}
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}
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}
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// Fall back to the parser's default behavior.
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return null;
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}
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```
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- systemId `https://www.springframework.org/dtd/spring-beans-2.0.dtd`
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## 总结
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- DelegatingEntityResolver#resolveEntity,是对xml文档的校验前置步骤,根据`dtd`和`xsd`加载本地资源文件
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`spring-framework\spring-beans\src\main\resources\org\springframework\beans\factory\xml\spring-beans.dtd`
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`spring-framework\spring-beans\src\main\resources\org\springframework\beans\factory\xml\spring-beans.xsd`
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- `PluggableSchemaResolver`负责加载`xsd`文件
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- `BeansDtdResolver`负责加载`dtd`文件
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@ -0,0 +1,307 @@
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# Spring-SimpleAliasRegistry
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [huifer-spring](https://github.com/huifer/spring-framework)
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## AliasRegistry
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- `SimpleAliasRegistry`继承`org.springframework.core.AliasRegistry`
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```java
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public interface AliasRegistry {
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/**
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* Given a name, register an alias for it.
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* 别名注册
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*
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* @param name the canonical name
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* @param alias the alias to be registered
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* @throws IllegalStateException if the alias is already in use
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* and may not be overridden
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* @see SimpleAliasRegistry
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* @see org.springframework.context.support.GenericApplicationContext
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*/
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void registerAlias(String name, String alias);
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/**
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* Remove the specified alias from this registry.
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* 别名移除
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*
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* @param alias the alias to remove
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* @throws IllegalStateException if no such alias was found
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*/
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void removeAlias(String alias);
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/**
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* Determine whether this given name is defines as an alias
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* (as opposed to the name of an actually registered component).
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* 是不是别名
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*
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* @param name the name to check
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* @return whether the given name is an alias
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*/
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boolean isAlias(String name);
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/**
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* Return the aliases for the given name, if defined.
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* 从别名注册map中获取别名信息
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*
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* @param name the name to check for aliases
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* @return the aliases, or an empty array if none
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*/
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String[] getAliases(String name);
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}
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```
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## SimpleAliasRegistry
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```java
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/**
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* Simple implementation of the {@link AliasRegistry} interface.
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* Serves as base class for
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* {@link org.springframework.beans.factory.support.BeanDefinitionRegistry}
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* implementations.
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*
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* @author Juergen Hoeller
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* @since 2.5.2
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*/
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public class SimpleAliasRegistry implements AliasRegistry {
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/**
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* Logger available to subclasses.
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*/
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protected final Log logger = LogFactory.getLog(getClass());
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/**
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* Map from alias to canonical name.
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* 存放别名的map(线程安全的),
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* 结构: alias-> name
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*/
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private final Map<String, String> aliasMap = new ConcurrentHashMap<>(16);
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/**
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* {@code <alias name="appleBean" alias="hhh"/>}
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*
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* @param name the canonical name
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* alias 标签的name属性
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* @param alias the alias to be registered
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* alias 标签的alias属性
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*/
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@Override
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public void registerAlias(String name, String alias) {
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Assert.hasText(name, "'name' must not be empty");
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Assert.hasText(alias, "'alias' must not be empty");
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synchronized (this.aliasMap) {
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// 判断: 别名和名字是否相同
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if (alias.equals(name)) {
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//相同在别名map中移除
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this.aliasMap.remove(alias);
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if (logger.isDebugEnabled()) {
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logger.debug("Alias definition '" + alias + "' ignored since it points to same name");
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}
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}
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else {
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// 不相同
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// 从map对象中获取别名为alias的value
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String registeredName = this.aliasMap.get(alias);
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if (registeredName != null) {
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// 判断map中是否有有一个别名和传入的name相同的内容
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if (registeredName.equals(name)) {
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// An existing alias - no need to re-register
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return;
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}
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if (!allowAliasOverriding()) {
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throw new IllegalStateException("Cannot define alias '" + alias + "' for name '" +
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name + "': It is already registered for name '" + registeredName + "'.");
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}
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if (logger.isDebugEnabled()) {
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logger.debug("Overriding alias '" + alias + "' definition for registered name '" +
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registeredName + "' with new target name '" + name + "'");
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}
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}
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// 别名环检查
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checkForAliasCircle(name, alias);
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// 放入 map 对象中 alias-> name
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this.aliasMap.put(alias, name);
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if (logger.isTraceEnabled()) {
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logger.trace("Alias definition '" + alias + "' registered for name '" + name + "'");
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}
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}
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}
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}
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/**
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* Return whether alias overriding is allowed.
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* Default is {@code true}.
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* 是否允许重写别名
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*/
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protected boolean allowAliasOverriding() {
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return true;
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}
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/**
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* Determine whether the given name has the given alias registered.
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* <p>
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* 递归判断是否已经存在别名
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*
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* @param name the name to check
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* @param alias the alias to look for
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* @since 4.2.1
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*/
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public boolean hasAlias(String name, String alias) {
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for (Map.Entry<String, String> entry : this.aliasMap.entrySet()) {
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// 获取key值
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String registeredName = entry.getValue();
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if (registeredName.equals(name)) {
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String registeredAlias = entry.getKey();
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// 循环引用判断
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if (registeredAlias.equals(alias) || hasAlias(registeredAlias, alias)) {
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return true;
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}
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}
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}
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return false;
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}
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||||
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/**
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* 别名移除
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*
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* @param alias the alias to remove
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*/
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@Override
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public void removeAlias(String alias) {
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synchronized (this.aliasMap) {
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// 判断是否移除成功
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String name = this.aliasMap.remove(alias);
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if (name == null) {
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throw new IllegalStateException("No alias '" + alias + "' registered");
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}
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}
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}
|
||||
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/**
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* 判断是否是一个别名,校验方式{@link org.springframework.core.SimpleAliasRegistry#aliasMap} 的key是否包含
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*
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* @param name the name to check
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* @return
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*/
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@Override
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public boolean isAlias(String name) {
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return this.aliasMap.containsKey(name);
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}
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/**
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* 获取别名列表
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*
|
||||
* @param name the name to check for aliases
|
||||
* @return
|
||||
*/
|
||||
@Override
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public String[] getAliases(String name) {
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List<String> result = new ArrayList<>();
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synchronized (this.aliasMap) {
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retrieveAliases(name, result);
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}
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return StringUtils.toStringArray(result);
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||||
}
|
||||
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||||
/**
|
||||
* Transitively retrieve all aliases for the given name.
|
||||
* 根据 name 获取别名
|
||||
*
|
||||
* @param name the target name to find aliases for
|
||||
* @param result the resulting aliases list
|
||||
*/
|
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private void retrieveAliases(String name, List<String> result) {
|
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// 循环获取
|
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this.aliasMap.forEach((alias, registeredName) -> {
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if (registeredName.equals(name)) {
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result.add(alias);
|
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// 递归查询循环引用的别名
|
||||
retrieveAliases(alias, result);
|
||||
}
|
||||
});
|
||||
}
|
||||
|
||||
/**
|
||||
* Resolve all alias target names and aliases registered in this
|
||||
* factory, applying the given StringValueResolver to them.
|
||||
* <p>The value resolver may for example resolve placeholders
|
||||
* in target bean names and even in alias names.
|
||||
*
|
||||
* @param valueResolver the StringValueResolver to apply
|
||||
*/
|
||||
public void resolveAliases(StringValueResolver valueResolver) {
|
||||
Assert.notNull(valueResolver, "StringValueResolver must not be null");
|
||||
synchronized (this.aliasMap) {
|
||||
Map<String, String> aliasCopy = new HashMap<>(this.aliasMap);
|
||||
aliasCopy.forEach((alias, registeredName) -> {
|
||||
String resolvedAlias = valueResolver.resolveStringValue(alias);
|
||||
String resolvedName = valueResolver.resolveStringValue(registeredName);
|
||||
if (resolvedAlias == null || resolvedName == null || resolvedAlias.equals(resolvedName)) {
|
||||
this.aliasMap.remove(alias);
|
||||
}
|
||||
else if (!resolvedAlias.equals(alias)) {
|
||||
String existingName = this.aliasMap.get(resolvedAlias);
|
||||
if (existingName != null) {
|
||||
if (existingName.equals(resolvedName)) {
|
||||
// Pointing to existing alias - just remove placeholder
|
||||
this.aliasMap.remove(alias);
|
||||
return;
|
||||
}
|
||||
throw new IllegalStateException(
|
||||
"Cannot register resolved alias '" + resolvedAlias + "' (original: '" + alias +
|
||||
"') for name '" + resolvedName + "': It is already registered for name '" +
|
||||
registeredName + "'.");
|
||||
}
|
||||
checkForAliasCircle(resolvedName, resolvedAlias);
|
||||
this.aliasMap.remove(alias);
|
||||
this.aliasMap.put(resolvedAlias, resolvedName);
|
||||
}
|
||||
else if (!registeredName.equals(resolvedName)) {
|
||||
this.aliasMap.put(alias, resolvedName);
|
||||
}
|
||||
});
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Check whether the given name points back to the given alias as an alias
|
||||
* in the other direction already, catching a circular reference upfront
|
||||
* and throwing a corresponding IllegalStateException.
|
||||
* <p>
|
||||
* 判断是否循环别名
|
||||
*
|
||||
* @param name the candidate name
|
||||
* @param alias the candidate alias
|
||||
* @see #registerAlias
|
||||
* @see #hasAlias
|
||||
*/
|
||||
protected void checkForAliasCircle(String name, String alias) {
|
||||
if (hasAlias(alias, name)) {
|
||||
throw new IllegalStateException("Cannot register alias '" + alias +
|
||||
"' for name '" + name + "': Circular reference - '" +
|
||||
name + "' is a direct or indirect alias for '" + alias + "' already");
|
||||
}
|
||||
}
|
||||
|
||||
/**
|
||||
* Determine the raw name, resolving aliases to canonical names.
|
||||
*
|
||||
* @param name the user-specified name
|
||||
* @return the transformed name
|
||||
*/
|
||||
public String canonicalName(String name) {
|
||||
String canonicalName = name;
|
||||
// Handle aliasing...
|
||||
String resolvedName;
|
||||
do {
|
||||
resolvedName = this.aliasMap.get(canonicalName);
|
||||
if (resolvedName != null) {
|
||||
canonicalName = resolvedName;
|
||||
}
|
||||
}
|
||||
while (resolvedName != null);
|
||||
return canonicalName;
|
||||
}
|
||||
|
||||
}
|
||||
|
||||
```
|
||||
|
After Width: | Height: | Size: 89 KiB |
|
After Width: | Height: | Size: 109 KiB |
|
After Width: | Height: | Size: 71 KiB |
|
After Width: | Height: | Size: 73 KiB |
|
After Width: | Height: | Size: 118 KiB |
|
After Width: | Height: | Size: 112 KiB |
|
After Width: | Height: | Size: 104 KiB |
|
After Width: | Height: | Size: 104 KiB |
|
After Width: | Height: | Size: 91 KiB |
|
After Width: | Height: | Size: 86 KiB |
|
After Width: | Height: | Size: 73 KiB |
|
After Width: | Height: | Size: 89 KiB |
|
After Width: | Height: | Size: 90 KiB |
|
After Width: | Height: | Size: 70 KiB |
|
After Width: | Height: | Size: 97 KiB |
Loading…
Reference in new issue