Spring 自定义属性解析器

用例

  1. <?xml version="1.0" encoding="UTF-8"?>
  2. <beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
  3.        xmlns="http://www.springframework.org/schema/beans"
  4.        xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
  6.     <bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
  7.         <property name="propertyEditorRegistrars">
  8.             <list>
  9.                 <bean class="com.huifer.source.spring.bean.DatePropertyRegister"/>
  10.             </list>
  11.         </property>
  13.         <property name="customEditors">
  14.             <map>
  15.                 <entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor">
  16.                 </entry>
  17.             </map>
  18.         </property>
  19.     </bean>
  20.     <bean id="apple" class="com.huifer.source.spring.bean.Apple">
  21.         <property name="date" value="2020-01-01 01:01:01"/>
  22.     </bean>
  23. </beans>
  1. public class DatePropertyRegister implements PropertyEditorRegistrar {
  2.     @Override
  3.     public void registerCustomEditors(PropertyEditorRegistry registry) {
  4.         registry.registerCustomEditor(Date.class, new CustomDateEditor(
  5.                 new SimpleDateFormat("yyyy-MM-dd"), true)
  6.         );
  7.     }
  8. }
  1. public class DatePropertyEditor extends PropertyEditorSupport {
  2.     private String format = "yyyy-MM-dd";
  4.     public String getFormat() {
  5.         return format;
  6.     }
  8.     public void setFormat(String format) {
  9.         this.format = format;
  10.     }
  12.     @Override
  13.     public void setAsText(String text) throws IllegalArgumentException {
  14.         System.out.println(text);
  15.         SimpleDateFormat sdf = new SimpleDateFormat(format);
  16.         try {
  17.             Date date = sdf.parse(text);
  18.             this.setValue(date);
  19.         } catch (Exception e) {
  20.             e.printStackTrace();
  22.         }
  23.     }
  25. }

PropertyEditorRegistrar 解析

  • 直接在DatePropertyRegister打上断点进行查看注册流程

    image-20200117104710142

    直接看调用堆栈获取调用层次

  1.     @Override
  2.     public void registerCustomEditor(Class<?> requiredType, PropertyEditor propertyEditor) {
  3.         registerCustomEditor(requiredType, null, propertyEditor);
  4.     }
  1.     @Override
  2.     public void registerCustomEditor(@Nullable Class<?> requiredType, @Nullable String propertyPath, PropertyEditor propertyEditor) {
  3.         if (requiredType == null && propertyPath == null) {
  4.             throw new IllegalArgumentException("Either requiredType or propertyPath is required");
  5.         }
  6.         if (propertyPath != null) {
  7.             if (this.customEditorsForPath == null) {
  8.                 this.customEditorsForPath = new LinkedHashMap<>(16);
  9.             }
  10.             this.customEditorsForPath.put(propertyPath, new CustomEditorHolder(propertyEditor, requiredType));
  11.         }
  12.         else {
  13.             if (this.customEditors == null) {
  14.                 this.customEditors = new LinkedHashMap<>(16);
  15.             }
  16.             // 放入 customEditors map对象中
  17.             this.customEditors.put(requiredType, propertyEditor);
  18.             this.customEditorCache = null;
  19.         }
  20.     }

  • PropertyEditorRegistrySupport

    image-20200117111131406

    此处对象是通过DatePropertyRegister传递的

  • org.springframework.beans.factory.support.AbstractBeanFactory#registerCustomEditors

  1.     protected void registerCustomEditors(PropertyEditorRegistry registry) {
  2.         PropertyEditorRegistrySupport registrySupport =
  3.                 (registry instanceof PropertyEditorRegistrySupport ? (PropertyEditorRegistrySupport) registry : null);
  4.         if (registrySupport != null) {
  5.             registrySupport.useConfigValueEditors();
  6.         }
  7.         if (!this.propertyEditorRegistrars.isEmpty()) {
  8.             for (PropertyEditorRegistrar registrar : this.propertyEditorRegistrars) {
  9.                 try {
  10.                     /**
  11.                      * {@link ResourceEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}或者
  12.                      * {@link PropertyEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}
  13.                      */
  14.                     registrar.registerCustomEditors(registry);
  15.                 }
  16.                 catch (BeanCreationException ex) {
  17.                     Throwable rootCause = ex.getMostSpecificCause();
  18.                     if (rootCause instanceof BeanCurrentlyInCreationException) {
  19.                         BeanCreationException bce = (BeanCreationException) rootCause;
  20.                         String bceBeanName = bce.getBeanName();
  21.                         if (bceBeanName != null && isCurrentlyInCreation(bceBeanName)) {
  22.                             if (logger.isDebugEnabled()) {
  23.                                 logger.debug("PropertyEditorRegistrar [" + registrar.getClass().getName() +
  24.                                         "] failed because it tried to obtain currently created bean '" +
  25.                                         ex.getBeanName() + "': " + ex.getMessage());
  26.                             }
  27.                             onSuppressedException(ex);
  28.                             continue;
  29.                         }
  30.                     }
  31.                     throw ex;
  32.                 }
  33.             }
  34.         }
  35.         if (!this.customEditors.isEmpty()) {
  36.             this.customEditors.forEach((requiredType, editorClass) ->
  37.                     registry.registerCustomEditor(requiredType, BeanUtils.instantiateClass(editorClass)));
  38.         }
  39.     }
  • void registerCustomEditors(PropertyEditorRegistry registry); 用例中编写的DatePropertyRegister正好有这个方法的实现

·

  • 在AbstractBeanFactory中查看变量

image-20200117110115741

  • 为什么最后结果变成com.huifer.source.spring.bean.DatePropertyEditor

    看配置文件

    1.         <property name="customEditors">
    2.             <map>
    3.                 <entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor">
    4.                 </entry>
    5.             </map>
    6.         </property>

    • 对应的 set 方法

      1.     public void setCustomEditors(Map<Class<?>, Class<? extends PropertyEditor>> customEditors) {
      2.         this.customEditors = customEditors;
      3.     }

      image-20200117110846256

applyPropertyValues

  • 应用属性值

    1.     protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) {
    2.         if (pvs.isEmpty()) {
    3.             return;
    4.         }
    6.         if (System.getSecurityManager() != null && bw instanceof BeanWrapperImpl) {
    7.             ((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext());
    8.         }
    10.         MutablePropertyValues mpvs = null;
    11.         // 没有解析的属性
    12.         List<PropertyValue> original;
    14.         if (pvs instanceof MutablePropertyValues) {
    15.             mpvs = (MutablePropertyValues) pvs;
    16.             if (mpvs.isConverted()) {
    17.                 //MutablePropertyValues 对象中存在转换后对象直接赋值
    18.                 // Shortcut: use the pre-converted values as-is.
    19.                 try {
    20.                     bw.setPropertyValues(mpvs);
    21.                     return;
    22.                 }
    23.                 catch (BeansException ex) {
    24.                     throw new BeanCreationException(
    25.                             mbd.getResourceDescription(), beanName, "Error setting property values", ex);
    26.                 }
    27.             }
    28.             original = mpvs.getPropertyValueList();
    29.         }
    30.         else {
    31.             original = Arrays.asList(pvs.getPropertyValues());
    32.         }
    33.         // 自定义转换器
    34.         TypeConverter converter = getCustomTypeConverter();
    35.         if (converter == null) {
    36.             converter = bw;
    37.         }
    38.         //  创建BeanDefinitionValueResolver
    39.         BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter);
    41.         // Create a deep copy, resolving any references for values.
    42.         // 解析后的对象集合
    43.         List<PropertyValue> deepCopy = new ArrayList<>(original.size());
    44.         boolean resolveNecessary = false;
    45.         for (PropertyValue pv : original) {
    46.             // 解析过的属性
    47.             if (pv.isConverted()) {
    48.                 deepCopy.add(pv);
    49.             }
    50.             // 没有解析过的属性
    51.             else {
    52.                 // 属性名称
    53.                 String propertyName = pv.getName();
    54.                 // 属性值,直接读取到的
    55.                 Object originalValue = pv.getValue();
    56.                 // 解析值
    57.                 Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue);
    58.                 Object convertedValue = resolvedValue;
    59.                 /**
    60.                  * 1. isWritableProperty: 属性可写
    61.                  * 2. isNestedOrIndexedProperty: 是否循环嵌套
    62.                  */
    63.                 boolean convertible = bw.isWritableProperty(propertyName) &&
    64.                         !PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName);
    65.                 if (convertible) {
    66.                     // 转换器解析
    67.                     convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter);
    68.                 }
    69.                 // Possibly store converted value in merged bean definition,
    70.                 // in order to avoid re-conversion for every created bean instance.
    71.                 if (resolvedValue == originalValue) {
    72.                     if (convertible) {
    73.                         // 设置解析值
    74.                         pv.setConvertedValue(convertedValue);
    75.                     }
    76.                     deepCopy.add(pv);
    77.                 }
    78.                 // 类型解析
    79.                 else if (convertible && originalValue instanceof TypedStringValue &&
    80.                         !((TypedStringValue) originalValue).isDynamic() &&
    81.                         !(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) {
    82.                     pv.setConvertedValue(convertedValue);
    83.                     deepCopy.add(pv);
    84.                 }
    85.                 else {
    86.                     resolveNecessary = true;
    87.                     deepCopy.add(new PropertyValue(pv, convertedValue));
    88.                 }
    89.             }
    90.         }
    91.         if (mpvs != null && !resolveNecessary) {
    92.             // 转换成功的标记方法
    93.             mpvs.setConverted();
    94.         }
    96.         // Set our (possibly massaged) deep copy.
    97.         try {
    98.             bw.setPropertyValues(new MutablePropertyValues(deepCopy));
    99.         }
    100.         catch (BeansException ex) {
    101.             throw new BeanCreationException(
    102.                     mbd.getResourceDescription(), beanName, "Error setting property values", ex);
    103.         }
    104.     }

    image-20200117133325461

image-20200117141309038

image-20200117141519123

  • 属性值解析

    image-20200117142800671

    1.     @Nullable
    2.     private Object convertForProperty(
    3.             @Nullable Object value, String propertyName, BeanWrapper bw, TypeConverter converter) {
    5.         if (converter instanceof BeanWrapperImpl) {
    6.             return ((BeanWrapperImpl) converter).convertForProperty(value, propertyName);
    7.         }
    8.         else {
    9.             PropertyDescriptor pd = bw.getPropertyDescriptor(propertyName);
    10.             MethodParameter methodParam = BeanUtils.getWriteMethodParameter(pd);
    11.             return converter.convertIfNecessary(value, pd.getPropertyType(), methodParam);
    12.         }
    13.     }
  1.     private Object doConvertTextValue(@Nullable Object oldValue, String newTextValue, PropertyEditor editor) {
  2.         try {
  3.             editor.setValue(oldValue);
  4.         }
  5.         catch (Exception ex) {
  6.             if (logger.isDebugEnabled()) {
  7.                 logger.debug("PropertyEditor [" + editor.getClass().getName() + "] does not support setValue call", ex);
  8.             }
  9.             // Swallow and proceed.
  10.         }
  11.         // 调用子类实现方法
  12.         editor.setAsText(newTextValue);
  13.         return editor.getValue();
  14.     }

  • 调用用例编写的方法

    1.     @Override
    2.     public void setAsText(String text) throws IllegalArgumentException {
    3.         System.out.println(text);
    4.         SimpleDateFormat sdf = new SimpleDateFormat(format);
    5.         try {
    6.             Date date = sdf.parse(text);
    7.             this.setValue(date);
    8.         } catch (Exception e) {
    9.             e.printStackTrace();
    11.         }
    12.     }

image-20200117143022827

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)