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374 lines
13 KiB
374 lines
13 KiB
# Spring 自定义属性解析器
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- Author: [HuiFer](https://github.com/huifer)
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- 源码阅读仓库: [SourceHot-Spring](https://github.com/SourceHot/spring-framework-read)
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## 用例
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```xml
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<?xml version="1.0" encoding="UTF-8"?>
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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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<bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
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<property name="propertyEditorRegistrars">
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<list>
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<bean class="com.huifer.source.spring.bean.DatePropertyRegister"/>
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</list>
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</property>
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<property name="customEditors">
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<map>
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<entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor">
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</entry>
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</map>
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</property>
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</bean>
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<bean id="apple" class="com.huifer.source.spring.bean.Apple">
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<property name="date" value="2020-01-01 01:01:01"/>
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</bean>
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</beans>
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```
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```java
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public class DatePropertyRegister implements PropertyEditorRegistrar {
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@Override
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public void registerCustomEditors(PropertyEditorRegistry registry) {
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registry.registerCustomEditor(Date.class, new CustomDateEditor(
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new SimpleDateFormat("yyyy-MM-dd"), true)
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);
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}
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}
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```
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```java
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public class DatePropertyEditor extends PropertyEditorSupport {
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private String format = "yyyy-MM-dd";
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public String getFormat() {
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return format;
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}
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public void setFormat(String format) {
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this.format = format;
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}
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@Override
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public void setAsText(String text) throws IllegalArgumentException {
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System.out.println(text);
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SimpleDateFormat sdf = new SimpleDateFormat(format);
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try {
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Date date = sdf.parse(text);
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this.setValue(date);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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}
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```
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## PropertyEditorRegistrar 解析
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- 直接在`DatePropertyRegister`打上断点进行查看注册流程
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直接看调用堆栈获取调用层次
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```java
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@Override
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public void registerCustomEditor(Class<?> requiredType, PropertyEditor propertyEditor) {
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registerCustomEditor(requiredType, null, propertyEditor);
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}
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```
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```java
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@Override
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public void registerCustomEditor(@Nullable Class<?> requiredType, @Nullable String propertyPath, PropertyEditor propertyEditor) {
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if (requiredType == null && propertyPath == null) {
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throw new IllegalArgumentException("Either requiredType or propertyPath is required");
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}
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if (propertyPath != null) {
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if (this.customEditorsForPath == null) {
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this.customEditorsForPath = new LinkedHashMap<>(16);
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}
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this.customEditorsForPath.put(propertyPath, new CustomEditorHolder(propertyEditor, requiredType));
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}
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else {
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if (this.customEditors == null) {
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this.customEditors = new LinkedHashMap<>(16);
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}
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// 放入 customEditors map对象中
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this.customEditors.put(requiredType, propertyEditor);
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this.customEditorCache = null;
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}
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}
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```
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- `PropertyEditorRegistrySupport`
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此处对象是通过`DatePropertyRegister`传递的
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- `org.springframework.beans.factory.support.AbstractBeanFactory#registerCustomEditors`
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```java
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protected void registerCustomEditors(PropertyEditorRegistry registry) {
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PropertyEditorRegistrySupport registrySupport =
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(registry instanceof PropertyEditorRegistrySupport ? (PropertyEditorRegistrySupport) registry : null);
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if (registrySupport != null) {
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registrySupport.useConfigValueEditors();
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}
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if (!this.propertyEditorRegistrars.isEmpty()) {
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for (PropertyEditorRegistrar registrar : this.propertyEditorRegistrars) {
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try {
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/**
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* {@link ResourceEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}或者
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* {@link PropertyEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}
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*/
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registrar.registerCustomEditors(registry);
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}
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catch (BeanCreationException ex) {
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Throwable rootCause = ex.getMostSpecificCause();
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if (rootCause instanceof BeanCurrentlyInCreationException) {
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BeanCreationException bce = (BeanCreationException) rootCause;
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String bceBeanName = bce.getBeanName();
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if (bceBeanName != null && isCurrentlyInCreation(bceBeanName)) {
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if (logger.isDebugEnabled()) {
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logger.debug("PropertyEditorRegistrar [" + registrar.getClass().getName() +
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"] failed because it tried to obtain currently created bean '" +
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ex.getBeanName() + "': " + ex.getMessage());
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}
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onSuppressedException(ex);
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continue;
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}
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}
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throw ex;
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}
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}
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}
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if (!this.customEditors.isEmpty()) {
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this.customEditors.forEach((requiredType, editorClass) ->
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registry.registerCustomEditor(requiredType, BeanUtils.instantiateClass(editorClass)));
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}
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}
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```
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- `void registerCustomEditors(PropertyEditorRegistry registry);` 用例中编写的`DatePropertyRegister`正好有这个方法的实现
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·
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- 在`AbstractBeanFactory`中查看变量
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- 为什么最后结果变成`com.huifer.source.spring.bean.DatePropertyEditor`
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看配置文件
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```xml
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<property name="customEditors">
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<map>
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<entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor">
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</entry>
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</map>
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</property>
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```
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- 对应的 set 方法
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```java
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public void setCustomEditors(Map<Class<?>, Class<? extends PropertyEditor>> customEditors) {
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this.customEditors = customEditors;
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}
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```
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## applyPropertyValues
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- 应用属性值
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```java
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protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
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if (pvs.isEmpty()) {
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return;
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}
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if (System.getSecurityManager() != null && bw instanceof BeanWrapperImpl) {
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((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
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}
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MutablePropertyValues mpvs = null;
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// 没有解析的属性
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List<PropertyValue> original;
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if (pvs instanceof MutablePropertyValues) {
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mpvs = (MutablePropertyValues) pvs;
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if (mpvs.isConverted()) {
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//MutablePropertyValues 对象中存在转换后对象直接赋值
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// Shortcut: use the pre-converted values as-is.
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try {
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bw.setPropertyValues(mpvs);
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return;
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}
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catch (BeansException ex) {
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throw new BeanCreationException(
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mbd.getResourceDescription(), beanName, "Error setting property values", ex);
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}
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}
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original = mpvs.getPropertyValueList();
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}
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else {
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original = Arrays.asList(pvs.getPropertyValues());
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}
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// 自定义转换器
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TypeConverter converter = getCustomTypeConverter();
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if (converter == null) {
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converter = bw;
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}
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// 创建BeanDefinitionValueResolver
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BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
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// Create a deep copy, resolving any references for values.
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// 解析后的对象集合
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List<PropertyValue> deepCopy = new ArrayList<>(original.size());
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boolean resolveNecessary = false;
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for (PropertyValue pv : original) {
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// 解析过的属性
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if (pv.isConverted()) {
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deepCopy.add(pv);
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}
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// 没有解析过的属性
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else {
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// 属性名称
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String propertyName = pv.getName();
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// 属性值,直接读取到的
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Object originalValue = pv.getValue();
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// 解析值
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Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
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Object convertedValue = resolvedValue;
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/**
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* 1. isWritableProperty: 属性可写
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* 2. isNestedOrIndexedProperty: 是否循环嵌套
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*/
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boolean convertible = bw.isWritableProperty(propertyName) &&
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!PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
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if (convertible) {
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// 转换器解析
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convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
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}
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// Possibly store converted value in merged bean definition,
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// in order to avoid re-conversion for every created bean instance.
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if (resolvedValue == originalValue) {
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if (convertible) {
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// 设置解析值
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pv.setConvertedValue(convertedValue);
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}
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deepCopy.add(pv);
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}
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// 类型解析
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else if (convertible && originalValue instanceof TypedStringValue &&
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!((TypedStringValue) originalValue).isDynamic() &&
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!(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
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pv.setConvertedValue(convertedValue);
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deepCopy.add(pv);
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}
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else {
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resolveNecessary = true;
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deepCopy.add(new PropertyValue(pv, convertedValue));
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}
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}
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}
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if (mpvs != null && !resolveNecessary) {
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// 转换成功的标记方法
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mpvs.setConverted();
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}
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// Set our (possibly massaged) deep copy.
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try {
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bw.setPropertyValues(new MutablePropertyValues(deepCopy));
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}
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catch (BeansException ex) {
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throw new BeanCreationException(
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mbd.getResourceDescription(), beanName, "Error setting property values", ex);
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}
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}
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```
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- 属性值解析
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```java
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@Nullable
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private Object convertForProperty(
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@Nullable Object value, String propertyName, BeanWrapper bw, TypeConverter converter) {
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if (converter instanceof BeanWrapperImpl) {
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return ((BeanWrapperImpl) converter).convertForProperty(value, propertyName);
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}
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else {
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PropertyDescriptor pd = bw.getPropertyDescriptor(propertyName);
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MethodParameter methodParam = BeanUtils.getWriteMethodParameter(pd);
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return converter.convertIfNecessary(value, pd.getPropertyType(), methodParam);
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}
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}
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```
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```java
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private Object doConvertTextValue(@Nullable Object oldValue, String newTextValue, PropertyEditor editor) {
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try {
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editor.setValue(oldValue);
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}
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catch (Exception ex) {
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if (logger.isDebugEnabled()) {
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logger.debug("PropertyEditor [" + editor.getClass().getName() + "] does not support setValue call", ex);
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}
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// Swallow and proceed.
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}
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// 调用子类实现方法
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editor.setAsText(newTextValue);
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return editor.getValue();
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}
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```
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- 调用用例编写的方法
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```java
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@Override
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public void setAsText(String text) throws IllegalArgumentException {
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System.out.println(text);
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SimpleDateFormat sdf = new SimpleDateFormat(format);
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try {
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Date date = sdf.parse(text);
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this.setValue(date);
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} catch (Exception e) {
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e.printStackTrace();
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}
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}
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```
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该值也是这个方法的返回`org.springframework.beans.TypeConverterDelegate#convertIfNecessary(java.lang.String, java.lang.Object, java.lang.Object, java.lang.Class<T>, org.springframework.core.convert.TypeDescriptor)`
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