Spring中的可扩展点（二）自定义属性编辑器

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我是靠谱客的博主酷炫刺猬，最近开发中收集的这篇文章主要介绍Spring中的可扩展点（二）自定义属性编辑器，觉得挺不错的，现在分享给大家，希望可以做个参考。

概述

1.自定义属性编辑器具体步骤

2.DEMO例程

2.1 创建Address类

2.2 创建Customer类，依赖于Address

2.3 创建自定义Editor

2.4 创建自定义Registrar

2.5 创建customizeEditor.xml配置文件

2.6 Application

2.7 结果演示

3.Spring是如何做到可扩展的

1.自定义属性编辑器具体步骤

自定义一个实现了PropertyEditorSupport接口的编辑器，重写setAsText方法。
让spring能够识别到这个自定义的编辑器，自定义一个属性编辑器的注册器，即实现PropertyEditorRegister接口
让spring能够识别到对应的注册器

2.DEMO例程

2.1 创建Address类

package com.zoo.customize.editor;

/**
 * @author Liu XiaoBai
 */
public class Address {
	private String province;
	private String city;
	private String town;

	public String getProvince() {
		return province;
	}

	public void setProvince(String province) {
		this.province = province;
	}

	public String getCity() {
		return city;
	}

	public void setCity(String city) {
		this.city = city;
	}

	public String getTown() {
		return town;
	}

	public void setTown(String town) {
		this.town = town;
	}

	@Override
	public String toString() {
		return "Address{" +
				"province='" + province + ''' +
				", city='" + city + ''' +
				", town='" + town + ''' +
				'}';
	}
}

2.2 创建Customer类，依赖于Address

package com.zoo.customize.editor;

/**
 * @author Liu XiaoBai
 */
public class Customer {

	private String name;
	private Address address;

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Address getAddress() {
		return address;
	}

	public void setAddress(Address address) {
		this.address = address;
	}

	@Override
	public String toString() {
		return "Customer{" +
				"name='" + name + ''' +
				", address=" + address +
				'}';
	}
}

2.3 创建自定义Editor

package com.zoo.customize.editor;

import java.beans.PropertyEditorSupport;

/**
 * @author Liu XiaoBai
 */
public class AddressPropertyEditor extends PropertyEditorSupport {
	@Override
	public void setAsText(String text) throws IllegalArgumentException {
		String[] s = text.split("_");
		Address address = new Address();
		address.setProvince(s[0]);
		address.setCity(s[1]);
		address.setTown(s[2]);
		this.setValue(address);
	}
}

2.4 创建自定义Registrar

package com.zoo.customize.editor;

import org.springframework.beans.PropertyEditorRegistrar;
import org.springframework.beans.PropertyEditorRegistry;

/**
 * @author Liu XiaoBai
 */
public class AddressPropertyEditorRegistrar implements PropertyEditorRegistrar {

	@Override
	public void registerCustomEditors(PropertyEditorRegistry registry) {
		registry.registerCustomEditor(Address.class,new AddressPropertyEditor());
	}
}

2.5 创建customizeEditor.xml配置文件

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

	   <bean id="customer" class="com.zoo.customize.editor.Customer">
		   <property name="name" value="tom"/>
		   <property name="address" value="河南省_漯河市_舞阳县"/>
	   </bean>

	   <bean class="org.springframework.beans.factory.config.CustomEditorConfigurer">
		   <property name="propertyEditorRegistrars">
			   <list>
				   <bean class="com.zoo.customize.editor.AddressPropertyEditorRegistrar"/>
			   </list>
		   </property>
	   </bean>
</beans>

2.6 Application

package com.zoo;

import com.zoo.customize.editor.Customer;
import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

/**
 * @author liuxiaobai
 */
public class Application {
	public static void main(String[] args) {

		AbstractApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml","customizeXsd.xml","customizeEditor.xml");
		Customer customer = (Customer)ac.getBean("customer");
		System.out.println(customer);
		ac.registerShutdownHook();
	}
}

2.7 结果演示

3.Spring是如何做到可扩展的

首先自定义的AddressPropertyEditorRegistrar将Address.class类的解析工作委托给了AddressPropertyEditor。然后customizeEditor.xml中将AddressPropertyEditorRegistrar添加到了CustomEditorConfigurer类propertyEditorRegistrars属性中，而CustomEditorConfigurer实现了BeanFactoryPostProcessor的，这样在集体处理BeanFactoryPostProcessors的时候就可以将程序中的AddressPropertyEditorRegistrar添加到Spring容器中。

具体注册AddressPropertyEditorRegistrar是在AbstractBeanFactory#initBeanWrapper中：

跟进此方法发现进行了自定义Editor的注册：

具体调用堆栈：

registerCustomEditors:1246, AbstractBeanFactory (org.springframework.beans.factory.support)
initBeanWrapper:1234, AbstractBeanFactory (org.springframework.beans.factory.support)
instantiateBean:1323, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createBeanInstance:1223, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
doCreateBean:559, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createBean:517, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
lambda$doGetBean$0:332, AbstractBeanFactory (org.springframework.beans.factory.support)
getObject:-1, 769429195 (org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$8)
getSingleton:238, DefaultSingletonBeanRegistry (org.springframework.beans.factory.support)
doGetBean:330, AbstractBeanFactory (org.springframework.beans.factory.support)
getBean:208, AbstractBeanFactory (org.springframework.beans.factory.support)
invokeBeanFactoryPostProcessors:172, PostProcessorRegistrationDelegate (org.springframework.context.support)
invokeBeanFactoryPostProcessors:766, AbstractApplicationContext (org.springframework.context.support)
refresh:549, AbstractApplicationContext (org.springframework.context.support)
<init>:145, ClassPathXmlApplicationContext (org.springframework.context.support)
<init>:95, ClassPathXmlApplicationContext (org.springframework.context.support)
main:13, Application (com.zoo)

解析的入口是在AbstractAutowireCapableBeanFactory#populateBean()：

最终一步步的会调用到我们自定义的编辑器中，调用堆栈：

setAsText:11, AddressPropertyEditor (com.zoo.customize.editor)
doConvertTextValue:429, TypeConverterDelegate (org.springframework.beans)
doConvertValue:402, TypeConverterDelegate (org.springframework.beans)
convertIfNecessary:155, TypeConverterDelegate (org.springframework.beans)
convertIfNecessary:590, AbstractNestablePropertyAccessor (org.springframework.beans)
convertForProperty:609, AbstractNestablePropertyAccessor (org.springframework.beans)
convertForProperty:219, BeanWrapperImpl (org.springframework.beans)
convertForProperty:1756, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
applyPropertyValues:1712, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
populateBean:1452, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
doCreateBean:598, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
createBean:517, AbstractAutowireCapableBeanFactory (org.springframework.beans.factory.support)
lambda$doGetBean$0:332, AbstractBeanFactory (org.springframework.beans.factory.support)
getObject:-1, 769429195 (org.springframework.beans.factory.support.AbstractBeanFactory$$Lambda$8)
getSingleton:238, DefaultSingletonBeanRegistry (org.springframework.beans.factory.support)
doGetBean:330, AbstractBeanFactory (org.springframework.beans.factory.support)
getBean:203, AbstractBeanFactory (org.springframework.beans.factory.support)
preInstantiateSingletons:902, DefaultListableBeanFactory (org.springframework.beans.factory.support)
finishBeanFactoryInitialization:939, AbstractApplicationContext (org.springframework.context.support)
refresh:577, AbstractApplicationContext (org.springframework.context.support)
<init>:145, ClassPathXmlApplicationContext (org.springframework.context.support)
<init>:95, ClassPathXmlApplicationContext (org.springframework.context.support)
main:13, Application (com.zoo)