javaBean中的PropertyEditor，扩展PropertyEditorSupport类，可以简化自定义PropertyEditor
目的：将字符串转化为正确的类型

注意：从spring3开始，spring引入了更简单和结构良好的类型转化API(Type Conversion API)和字段格式化SPI(Field Formatting Service Provider Interface)(第10章)

样例

源码 chapter04/property-editors

代码结构图

独立应用程序中CustomDateEditor和StringTrimmerEditor这两个编辑器默认情况下并未在spring中注册

package com.apress.prospring5.ch4;

import java.io.File;
import java.io.InputStream;
import java.net.URL;
import java.util.*;
import java.util.regex.Pattern;
import java.text.SimpleDateFormat;
import org.springframework.beans.PropertyEditorRegistrar;
import org.springframework.beans.PropertyEditorRegistry;
import org.springframework.beans.propertyeditors.CustomDateEditor;
import org.springframework.beans.propertyeditors.StringTrimmerEditor;

import org.springframework.context.support.GenericXmlApplicationContext;

public class PropertyEditorBean {
    private byte[] bytes;                 // ByteArrayPropertyEditor
    private Character character;          //CharacterEditor
    private Class cls;                    // ClassEditor
    private Boolean trueOrFalse;          // CustomBooleanEditor
    private List<String> stringList;      // CustomCollectionEditor
    private Date date;                    // CustomDateEditor
    private Float floatValue;             // CustomNumberEditor
    private File file;                    // FileEditor
    private InputStream stream;           // InputStreamEditor
    private Locale locale;                // LocaleEditor
    private Pattern pattern;              // PatternEditor
    private Properties properties;        // PropertiesEditor
    private String trimString;            // StringTrimmerEditor
    private URL url;                      // URLEditor

    public void setCharacter(Character character) {
        System.out.println("Setting character: " + character);
        this.character = character;
    }

    public void setCls(Class cls) {
        System.out.println("Setting class: " + cls.getName());
        this.cls = cls;
    }

    public void setFile(File file) {
        System.out.println("Setting file: " + file.getName());
        this.file = file;
    }

    public void setLocale(Locale locale) {
        System.out.println("Setting locale: " + locale.getDisplayName());
        this.locale = locale;
    }

    public void setProperties(Properties properties) {
        System.out.println("Loaded " + properties.size() + " properties");
        this.properties = properties;
    }

    public void setUrl(URL url) {
        System.out.println("Setting URL: " + url.toExternalForm());
        this.url = url;
    }

    public void setBytes(byte... bytes) {
        System.out.println("Setting bytes: " + Arrays.toString(bytes));
        this.bytes = bytes;
    }

    public void setTrueOrFalse(Boolean trueOrFalse) {
        System.out.println("Setting Boolean: " + trueOrFalse);
        this.trueOrFalse = trueOrFalse;
    }

    public void setStringList(List<String> stringList) {
        System.out.println("Setting string list with size: "
            + stringList.size());

        this.stringList = stringList;

        for (String string: stringList) {
            System.out.println("String member: " + string);
        }
    }

    public void setDate(Date date) {
        System.out.println("Setting date: " + date);
        this.date = date;
    }

    public void setFloatValue(Float floatValue) {
        System.out.println("Setting float value: " + floatValue);
        this.floatValue = floatValue;
    }

    public void setStream(InputStream stream) {
        System.out.println("Setting stream: " + stream);
        this.stream = stream;
    }

    public void setPattern(Pattern pattern) {
        System.out.println("Setting pattern: " + pattern);
        this.pattern = pattern;
    }

    public void setTrimString(String trimString) {
        System.out.println("Setting trim string: " + trimString);
        this.trimString = trimString;
    }

    public static class CustomPropertyEditorRegistrar implements PropertyEditorRegistrar { 
        @Override
        public void registerCustomEditors(PropertyEditorRegistry registry) {
            SimpleDateFormat dateFormatter = new SimpleDateFormat("MM/dd/yyyy");
            registry.registerCustomEditor(Date.class, 
                     new CustomDateEditor(dateFormatter, true));

            registry.registerCustomEditor(String.class, new StringTrimmerEditor(true));
        }
    }

    public static void main(String... args) throws Exception {
        File file = File.createTempFile("test", "txt");
        file.deleteOnExit();

        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
        ctx.load("classpath:spring/app-context-01.xml");
        ctx.refresh();

        PropertyEditorBean bean = 
            (PropertyEditorBean) ctx.getBean("builtInSample");

        ctx.close();
    }
}

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:util="http://www.springframework.org/schema/util"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd
        http://www.springframework.org/schema/util    
        http://www.springframework.org/schema/util/spring-util.xsd">

    <bean id="customEditorConfigurer" 
        class="org.springframework.beans.factory.config.CustomEditorConfigurer"
        p:propertyEditorRegistrars-ref="propertyEditorRegistrarsList"/>
   
    <util:list id="propertyEditorRegistrarsList">
        <bean class="com.apress.prospring5.ch4.PropertyEditorBean$CustomPropertyEditorRegistrar"/>
    </util:list>

    <bean id="builtInSample" class="com.apress.prospring5.ch4.PropertyEditorBean"
          p:character="A"
        p:bytes="John Mayer"
        p:cls="java.lang.String"
        p:trueOrFalse="true"
        p:stringList-ref="stringList"
        p:stream="test.txt"
        p:floatValue="123.45678"
        p:date="05/03/13"
        p:file="#{systemProperties['java.io.tmpdir']}#{systemProperties['file.separator']}test.txt"
        p:locale="en_US"
        p:pattern="a*b"
        p:properties="name=Chris age=32"
        p:trimString="   String need trimming   "
        p:url="https://spring.io/"
    /> 

    <util:list id="stringList">
        <value>String member 1</value>
        <value>String member 2</value>
    </util:list>
</beans>

执行结果

Setting bytes: [74, 111, 104, 110, 32, 77, 97, 121, 101, 114]
Setting character: A
Setting class: java.lang.String
Setting date: Wed May 03 00:00:00 CST 13
Setting file: test.txt
Setting float value: 123.45678
Setting locale: 英文 (美国)
Setting pattern: a*b
Loaded 1 properties
Setting stream: java.io.BufferedInputStream@d4342c2
Setting string list with size: 2
String member: String member 1
String member: String member 2
Setting trim string: String need trimming
Setting Boolean: true
Setting URL: https://spring.io/

4.12.2创建自定义PropertyEditor

方法
继承PropertyEditorSupport，覆盖setAsText(String)方法

package com.apress.prospring5.ch4.custom;

public class FullName {
    private String firstName;
    private String lastName;

    public FullName(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String toString() {
        return "First name: " + firstName + " - Last name: " + lastName;
    }
}

package com.apress.prospring5.ch4.custom;

import java.beans.PropertyEditorSupport;

public class NamePropertyEditor extends PropertyEditorSupport {
    @Override
    public void setAsText(String text) throws IllegalArgumentException {
        String[] name = text.split("\\s");

        setValue(new FullName(name[0], name[1]));
    }
}

通过CustomEditorConfigurer注册所需编辑器

<?xml version="1.0" encoding="UTF-8"?>

<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
    xmlns:p="http://www.springframework.org/schema/p"
    xsi:schemaLocation="http://www.springframework.org/schema/beans
        http://www.springframework.org/schema/beans/spring-beans.xsd">

    <bean name="customEditorConfigurer"
          class="org.springframework.beans.factory.config.CustomEditorConfigurer">
        <property name="customEditors">
            <map>
                <entry key="com.apress.prospring5.ch4.custom.FullName"
                       value="com.apress.prospring5.ch4.custom.NamePropertyEditor"/>
            </map>
        </property>
    </bean>

    <bean id="exampleBean" class="com.apress.prospring5.ch4.custom.CustomEditorExample"
      p:name="John Mayer"/>
</beans>

package com.apress.prospring5.ch4.custom;

import org.springframework.context.support.GenericXmlApplicationContext;

public class CustomEditorExample {
    private FullName name;

    public FullName getName() {
        return name;
    }

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

    public static void main(String... args) {
        GenericXmlApplicationContext ctx = new GenericXmlApplicationContext();
        ctx.load("classpath:spring/app-context-02.xml");
        ctx.refresh();

        CustomEditorExample bean =
            (CustomEditorExample) ctx.getBean("exampleBean");

        System.out.println(bean.getName());

        ctx.close();
    }
}

执行结果

First name: John - Last name: Mayer