Spring 自定义属性解析器

• Author: HuiFer
• 源码阅读仓库: SourceHot-Spring

用例

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<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       xmlns="http://www.springframework.org/schema/beans"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
        <property name="propertyEditorRegistrars">
            <list>
                <bean class="com.huifer.source.spring.bean.DatePropertyRegister"/>
            </list>
        </property>

        <property name="customEditors">
            <map>
                <entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor">
                </entry>
            </map>
        </property>
    </bean>
    <bean id="apple" class="com.huifer.source.spring.bean.Apple">
        <property name="date" value="2020-01-01 01:01:01"/>
    </bean>
</beans>

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public class DatePropertyRegister implements PropertyEditorRegistrar {
    @Override
    public void registerCustomEditors(PropertyEditorRegistry registry) {
        registry.registerCustomEditor(Date.class, new CustomDateEditor(
                new SimpleDateFormat("yyyy-MM-dd"), true)
        );
    }
}

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public class DatePropertyEditor extends PropertyEditorSupport {
    private String format = "yyyy-MM-dd";

    public String getFormat() {
        return format;
    }

    public void setFormat(String format) {
        this.format = format;
    }

    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        System.out.println(text);
        SimpleDateFormat sdf = new SimpleDateFormat(format);
        try {
            Date date = sdf.parse(text);
            this.setValue(date);
        } catch (Exception e) {
            e.printStackTrace();

        }
    }

}

PropertyEditorRegistrar 解析

• 直接在DatePropertyRegister打上断点进行查看注册流程

  

  直接看调用堆栈获取调用层次

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    @Override
    public void registerCustomEditor(Class<?> requiredType, PropertyEditor propertyEditor) {
        registerCustomEditor(requiredType, null, propertyEditor);
    }

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    @Override
    public void registerCustomEditor(@Nullable Class<?> requiredType, @Nullable String propertyPath, PropertyEditor propertyEditor) {
        if (requiredType == null && propertyPath == null) {
            throw new IllegalArgumentException("Either requiredType or propertyPath is required");
        }
        if (propertyPath != null) {
            if (this.customEditorsForPath == null) {
                this.customEditorsForPath = new LinkedHashMap<>(16);
            }
            this.customEditorsForPath.put(propertyPath, new CustomEditorHolder(propertyEditor, requiredType));
        }
        else {
            if (this.customEditors == null) {
                this.customEditors = new LinkedHashMap<>(16);
            }
            // 放入 customEditors map对象中
            this.customEditors.put(requiredType, propertyEditor);
            this.customEditorCache = null;
        }
    }

• PropertyEditorRegistrySupport

  

  此处对象是通过DatePropertyRegister传递的

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

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    protected void registerCustomEditors(PropertyEditorRegistry registry) {
        PropertyEditorRegistrySupport registrySupport =
                (registry instanceof PropertyEditorRegistrySupport ? (PropertyEditorRegistrySupport) registry : null);
        if (registrySupport != null) {
            registrySupport.useConfigValueEditors();
        }
        if (!this.propertyEditorRegistrars.isEmpty()) {
            for (PropertyEditorRegistrar registrar : this.propertyEditorRegistrars) {
                try {
                    /**
                     * {@link ResourceEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}或者
                     * {@link PropertyEditorRegistrar#registerCustomEditors(org.springframework.beans.PropertyEditorRegistry)}
                     */
                    registrar.registerCustomEditors(registry);
                }
                catch (BeanCreationException ex) {
                    Throwable rootCause = ex.getMostSpecificCause();
                    if (rootCause instanceof BeanCurrentlyInCreationException) {
                        BeanCreationException bce = (BeanCreationException) rootCause;
                        String bceBeanName = bce.getBeanName();
                        if (bceBeanName != null && isCurrentlyInCreation(bceBeanName)) {
                            if (logger.isDebugEnabled()) {
                                logger.debug("PropertyEditorRegistrar [" + registrar.getClass().getName() +
                                        "] failed because it tried to obtain currently created bean '" +
                                        ex.getBeanName() + "': " + ex.getMessage());
                            }
                            onSuppressedException(ex);
                            continue;
                        }
                    }
                    throw ex;
                }
            }
        }
        if (!this.customEditors.isEmpty()) {
            this.customEditors.forEach((requiredType, editorClass) ->
                    registry.registerCustomEditor(requiredType, BeanUtils.instantiateClass(editorClass)));
        }
    }

• 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

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

  看配置文件

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  <property name="customEditors"> <map> <entry key="java.util.Date" value="com.huifer.source.spring.bean.DatePropertyEditor"> </entry> </map> </property>

  • 对应的 set 方法

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

    

applyPropertyValues

• 应用属性值

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  protected void applyPropertyValues(String beanName, BeanDefinition mbd, BeanWrapper bw, PropertyValues pvs) { if (pvs.isEmpty()) { return; } if (System.getSecurityManager() != null && bw instanceof BeanWrapperImpl) { ((BeanWrapperImpl) bw).setSecurityContext(getAccessControlContext()); } MutablePropertyValues mpvs = null; // 没有解析的属性 List<PropertyValue> original; if (pvs instanceof MutablePropertyValues) { mpvs = (MutablePropertyValues) pvs; if (mpvs.isConverted()) { //MutablePropertyValues 对象中存在转换后对象直接赋值 // Shortcut: use the pre-converted values as-is. try { bw.setPropertyValues(mpvs); return; } catch (BeansException ex) { throw new BeanCreationException( mbd.getResourceDescription(), beanName, "Error setting property values", ex); } } original = mpvs.getPropertyValueList(); } else { original = Arrays.asList(pvs.getPropertyValues()); } // 自定义转换器 TypeConverter converter = getCustomTypeConverter(); if (converter == null) { converter = bw; } // 创建BeanDefinitionValueResolver BeanDefinitionValueResolver valueResolver = new BeanDefinitionValueResolver(this, beanName, mbd, converter); // Create a deep copy, resolving any references for values. // 解析后的对象集合 List<PropertyValue> deepCopy = new ArrayList<>(original.size()); boolean resolveNecessary = false; for (PropertyValue pv : original) { // 解析过的属性 if (pv.isConverted()) { deepCopy.add(pv); } // 没有解析过的属性 else { // 属性名称 String propertyName = pv.getName(); // 属性值,直接读取到的 Object originalValue = pv.getValue(); // 解析值 Object resolvedValue = valueResolver.resolveValueIfNecessary(pv, originalValue); Object convertedValue = resolvedValue; /** * 1. isWritableProperty: 属性可写 * 2. isNestedOrIndexedProperty: 是否循环嵌套 */ boolean convertible = bw.isWritableProperty(propertyName) && !PropertyAccessorUtils.isNestedOrIndexedProperty(propertyName); if (convertible) { // 转换器解析 convertedValue = convertForProperty(resolvedValue, propertyName, bw, converter); } // Possibly store converted value in merged bean definition, // in order to avoid re-conversion for every created bean instance. if (resolvedValue == originalValue) { if (convertible) { // 设置解析值 pv.setConvertedValue(convertedValue); } deepCopy.add(pv); } // 类型解析 else if (convertible && originalValue instanceof TypedStringValue && !((TypedStringValue) originalValue).isDynamic() && !(convertedValue instanceof Collection || ObjectUtils.isArray(convertedValue))) { pv.setConvertedValue(convertedValue); deepCopy.add(pv); } else { resolveNecessary = true; deepCopy.add(new PropertyValue(pv, convertedValue)); } } } if (mpvs != null && !resolveNecessary) { // 转换成功的标记方法 mpvs.setConverted(); } // Set our (possibly massaged) deep copy. try { bw.setPropertyValues(new MutablePropertyValues(deepCopy)); } catch (BeansException ex) { throw new BeanCreationException( mbd.getResourceDescription(), beanName, "Error setting property values", ex); } }

  

• 属性值解析

  

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  @Nullable private Object convertForProperty( @Nullable Object value, String propertyName, BeanWrapper bw, TypeConverter converter) { if (converter instanceof BeanWrapperImpl) { return ((BeanWrapperImpl) converter).convertForProperty(value, propertyName); } else { PropertyDescriptor pd = bw.getPropertyDescriptor(propertyName); MethodParameter methodParam = BeanUtils.getWriteMethodParameter(pd); return converter.convertIfNecessary(value, pd.getPropertyType(), methodParam); } }

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    private Object doConvertTextValue(@Nullable Object oldValue, String newTextValue, PropertyEditor editor) {
        try {
            editor.setValue(oldValue);
        }
        catch (Exception ex) {
            if (logger.isDebugEnabled()) {
                logger.debug("PropertyEditor [" + editor.getClass().getName() + "] does not support setValue call", ex);
            }
            // Swallow and proceed.
        }
        // 调用子类实现方法
        editor.setAsText(newTextValue);
        return editor.getValue();
    }

• 调用用例编写的方法

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  @Override public void setAsText(String text) throws IllegalArgumentException { System.out.println(text); SimpleDateFormat sdf = new SimpleDateFormat(format); try { Date date = sdf.parse(text); this.setValue(date); } catch (Exception e) { e.printStackTrace(); } }

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)