关于Spring属性编辑器详解

关于Spring属性编辑器详解(转)

关于Spring属性编辑器详解 原文出处： http://stamen.javaeye.com/blog/24660 最近刚在研究Spring的编辑器，发现很有意思，刚好galaxystar起了一个这样贴，我想对PropertyEditor作一个详细的整理会对大家有益，特定启了这个新帖。 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： 代码 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 代码 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 代码 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 代码 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： 代码 <bean id="customEditorConfigurer" class="org.springframework.beans.factory.config.CustomEditorConfigurer"> <property name="customEditors"> <map> <entry key="com.stamen.propedit.Address"> <!-- key为需要转换的类 --> <bean class="com.stamen.propedit.AddressPropertyEditor"/> <!--对应的转换类 --> </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>

下面是我自己写的日期转换类：
package com.lt.resource.propertyeditor; import java.beans.PropertyEditorSupport; import java.text.SimpleDateFormat; import org.springframework.util.StringUtils; public class DatePropertyEditor extends PropertyEditorSupport { private String format = "yyyy-MM-dd"; //缺省 public void setFormat(String format) { this.format = format; } public void setAsText(String text) throws IllegalArgumentException { if (text != null || StringUtils.hasText(text)) { setValue(new SimpleDateFormat(this.format).format(text)); } } }
我的配置：
<bean id="customEditorConfigurer" class="org.springframework.beans.factory.config.CustomEditorConfigurer"> <property name="customEditors"> <map> <entry key="java.util.Date"> <bean class="com.lt.resource.propertyeditor.DatePropertyEditor"> <property name="format" value="yyyy年MM月dd日 HH时mm分ss秒" /> </bean> </entry> </map> </property> </bean>