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锁定老帖子 主题:关于Spring属性编辑器详解
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发表时间:2006-09-20
所谓的PropertyEditor,顾名思义,就是属性编辑器。由于Bean属性通过配置文档以字符串了方式为属性赋值,所以必须有一个“东东”负责将这个字符串转换为属性的直接对象,如属性的类型为int,那么编辑器要做的工作就是int i = Integer.parseInt("1"); Spring为一般的属性类型提供了默认的编辑器,BeanWrapperImpl是Spring框架中重要的类,它负责对注入的Bean进行包装化的管理,常见属性类型对应的编辑器即在该类中通过以下代码定义: private void registerDefaultEditors() { // Simple editors, without parameterization capabilities. // The JDK does not contain a default editor for any of these target types. this.defaultEditors.put(byte[].class, new ByteArrayPropertyEditor()); this.defaultEditors.put(Class.class, new ClassEditor()); this.defaultEditors.put(File.class, new FileEditor()); this.defaultEditors.put(InputStream.class, new InputStreamEditor()); this.defaultEditors.put(Locale.class, new LocaleEditor()); this.defaultEditors.put(Properties.class, new PropertiesEditor()); this.defaultEditors.put(Resource[].class, new ResourceArrayPropertyEditor()); this.defaultEditors.put(String[].class, new StringArrayPropertyEditor()); this.defaultEditors.put(URL.class, new URLEditor()); // Default instances of collection editors. // Can be overridden by registering custom instances of those as custom editors. this.defaultEditors.put(Collection.class, new CustomCollectionEditor(Collection.class)); this.defaultEditors.put(Set.class, new CustomCollectionEditor(Set.class)); this.defaultEditors.put(SortedSet.class, new CustomCollectionEditor(SortedSet.class)); this.defaultEditors.put(List.class, new CustomCollectionEditor(List.class)); // Default instances of character and boolean editors. // Can be overridden by registering custom instances of those as custom editors. PropertyEditor characterEditor = new CharacterEditor(false); PropertyEditor booleanEditor = new CustomBooleanEditor(false); // The JDK does not contain a default editor for char! this.defaultEditors.put(char.class, characterEditor); this.defaultEditors.put(Character.class, characterEditor); // Spring's CustomBooleanEditor accepts more flag values than the JDK's default editor. this.defaultEditors.put(boolean.class, booleanEditor); this.defaultEditors.put(Boolean.class, booleanEditor); // The JDK does not contain default editors for number wrapper types! // Override JDK primitive number editors with our own CustomNumberEditor. PropertyEditor byteEditor = new CustomNumberEditor(Byte.class, false); PropertyEditor shortEditor = new CustomNumberEditor(Short.class, false); PropertyEditor integerEditor = new CustomNumberEditor(Integer.class, false); PropertyEditor longEditor = new CustomNumberEditor(Long.class, false); PropertyEditor floatEditor = new CustomNumberEditor(Float.class, false); PropertyEditor doubleEditor = new CustomNumberEditor(Double.class, false); this.defaultEditors.put(byte.class, byteEditor); this.defaultEditors.put(Byte.class, byteEditor); this.defaultEditors.put(short.class, shortEditor); this.defaultEditors.put(Short.class, shortEditor); this.defaultEditors.put(int.class, integerEditor); this.defaultEditors.put(Integer.class, integerEditor); this.defaultEditors.put(long.class, longEditor); this.defaultEditors.put(Long.class, longEditor); this.defaultEditors.put(float.class, floatEditor); this.defaultEditors.put(Float.class, floatEditor); this.defaultEditors.put(double.class, doubleEditor); this.defaultEditors.put(Double.class, doubleEditor); this.defaultEditors.put(BigDecimal.class, new CustomNumberEditor(BigDecimal.class, false)); this.defaultEditors.put(BigInteger.class, new CustomNumberEditor(BigInteger.class, false)); } 但是,并非Bean的属性都是这些常见的类型,如果你的Bean需要注入一个自定义类型的属性,而又想享受IoC的好处,那么就只得自己开干,提供一个自定义的PropertyEditor了。 下面,分几个步骤来说明,定义一个自定义PropertyEditor的过程。 1)首先,碰到的问题即是,要如何编辑自己的PropertyEditor,其实需要了解一点java.beans包的知识,在该包中,有一个java.beans.PropertyEditor的接口,它定义了一套接口方法(12个),即通过这些方法如何将一个String变成内部的一个对象,这两个方法是比较重要的: a)setValue(Object value) 直接设置一个对象,一般不直接用该方法设置属性对象 b)setAsText(String text) 通过一个字符串来构造对象,一般在此方法中解析字符串,将构造一个 类对象,调用setValue(Object)来完成属性对象设置操作。 2)实现所有的接口方法是麻烦的,java.beans.PropertyEditorSupport 适时登场,一般情况下,我们通过扩展这个方便类即可。 3)编写完后,就是在Spring配置文件中注册该属性类型编辑器的问题,Spring提供了专门的注册工具类 org.springframework.beans.factory.config.CustomEditorConfigurer,它负责将属性类型和 属性编辑器关联起来。到时BeanFactory注入Bean的属性时,即会在注册表中查找属性类型对应的编辑器。 下面给出一个小例子,例子先作一个简单描述: 1)Person 需要进行属性注入的Bean,有两个属性 一个是name,一个是address Address是一个类 2)Address Person的属性类型,本身有3个属性。 3)AddressPropertyEditor Address类型对应的属性编辑器。 开工: 1.Person.java package com.stamen.propedit; import org.apache.commons.lang.builder.ToStringBuilder; public class Person { private String name; private Address address; public Address getAddress() { return address; } public void setAddress(Address address) { this.address = address; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String toString() { return ToStringBuilder.reflectionToString(this); } } 2.Address.java package com.stamen.propedit; import org.apache.commons.lang.builder.ToStringBuilder; public class Address { private String street; private String doorNum; private String postCode; public String getDoorNum() { return doorNum; } public void setDoorNum(String doorNum) { this.doorNum = doorNum; } public String getPostCode() { return postCode; } public void setPostCode(String postCode) { this.postCode = postCode; } public String getStreet() { return street; } public void setStreet(String street) { this.street = street; } public String toString() { return ToStringBuilder.reflectionToString(this); } } AddressPropertyEditor.java package com.stamen.propedit; import java.beans.PropertyEditorSupport; import java.util.Date; import org.springframework.util.StringUtils; public class AddressPropertyEditor extends PropertyEditorSupport{ //支持的格式为 streeValue,doorNumValue,postCode public void setAsText(String text) { System.out.println("使用自己的编辑器。"); if (text == null || !StringUtils.hasText(text)) { throw new IllegalArgumentException("老大,不能为空啊!"); } else { String[] strArr = StringUtils.tokenizeToStringArray(text,","); Address add = new Address(); add.setStreet(strArr[0]); add.setDoorNum(strArr[1]); add.setPostCode(strArr[2]); setValue(add); } } public String getAsText() { Address add = (Address)getValue(); return ""+add; } } 打开Spring配置文件,添上这两个配置项: <bean id="customEditorConfigurer" class="org.springframework.beans.factory.config.CustomEditorConfigurer"> <property name="customEditors"> <map> <entry key="com.stamen.propedit.Address"> <!-- 属性类型 --> <bean class="com.stamen.propedit.AddressPropertyEditor"/> <!--对应Address的编辑器 --> </entry> </map> </property> </bean> <bean id="person" class="com.stamen.propedit.Person"> <property name="name" value="Tom"/> <property name="address" value="朝阳区,Soho 1601,010101"/> </bean> 收工,刷牙,上床,睡觉。 声明:ITeye文章版权属于作者,受法律保护。没有作者书面许可不得转载。
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发表时间:2006-09-20
spring-modules-springmvc-extra 中有个 ReflectivePropertyEditor.
用reflect实现的, 直接在<bean>中定义propertyEditor,省去了实现xxxPropertyEditor类的麻烦... |
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发表时间:2006-09-20
simbasun 写道 spring-modules-springmvc-extra 中有个 ReflectivePropertyEditor.
用reflect实现的, 直接在<bean>中定义propertyEditor,省去了实现xxxPropertyEditor类的麻烦... "直接在<bean>中定义propertyEditor",用反射来进行类型转换,你还是要写一个作为反射调用的bean吧!(转换逻辑) "xxxPropertyEditor"也是实现了propertyEditor不是的吗?何况反射的使用要谨慎! |
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发表时间:2006-09-20
还有楼主好像贴了2遍原文!难怪那么长?
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发表时间:2006-09-20
galaxystar 写道 还有楼主好像贴了2遍原文!难怪那么长?
Sorry,昨天太晚贴了,已经睡眼惺忪,改了,改了... |
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发表时间:2006-09-20
写得不错!正好解决我的疑问!
另,spring做什么都那么有条理!欣赏! 不过我还是喜欢简单的事情简单做!而且我比较少碰到在配置中经常要转换! |
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发表时间:2006-09-21
不错,Spring就是强。
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