吴裕雄--天生自然轻量级JAVA EE企业应用开发Struts2Sping4Hibernate整合开发学习笔记：Spring_GetFieldFactoryBean

<?xml version="1.0" encoding="GBK"?>
<project name="spring" basedir="." default="">
    <property name="src" value="src"/>
    <property name="dest" value="classes"/>

    <path id="classpath">
        <fileset dir="../../lib">
            <include name="**/*.jar"/>
        </fileset>
        <pathelement path="${dest}"/>
    </path>

    <target name="compile" description="Compile all source code">
        <delete dir="${dest}"/>
        <mkdir dir="${dest}"/>
        <copy todir="${dest}">
            <fileset dir="${src}">
                <exclude name="**/*.java"/>
            </fileset>        
        </copy>
        <javac destdir="${dest}" debug="true" includeantruntime="yes"
            deprecation="false" optimize="false" failonerror="true">
            <src path="${src}"/>
            <classpath refid="classpath"/>
            <compilerarg value="-Xlint:deprecation"/>
        </javac>
    </target>

    <target name="run" description="Run the main class" depends="compile">
        <java classname="lee.SpringTest" fork="yes" failonerror="true">
            <classpath refid="classpath"/>
        </java>
    </target>

</project>

<?xml version="1.0" encoding="GBK"?>
<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-4.0.xsd">
    <!-- 下面配置相当于如下代码：
    FactoryBean factory = new org.crazyit.app.factory.GetFieldFactoryBean();
    factory.setTargetClass("java.awt.BorderLayout");
    factory.setTargetField("NORTH");
    north = factory.getObject(); -->
    <bean id="north" class="org.crazyit.app.factory.GetFieldFactoryBean">
        <property name="targetClass" value="java.awt.BorderLayout"/>
        <property name="targetField" value="NORTH"/>
    </bean>
    <!-- 下面配置相当于如下代码：
    FactoryBean factory = new org.crazyit.app.factory.GetFieldFactoryBean();
    factory.setTargetClass("java.sql.ResultSet");
    factory.setTargetField("TYPE_SCROLL_SENSITIVE");
    north = factory.getObject(); -->
    <bean id="theValue" class="org.crazyit.app.factory.GetFieldFactoryBean">
        <property name="targetClass" value="java.sql.ResultSet"/>
        <property name="targetField" value="TYPE_SCROLL_SENSITIVE"/>
    </bean>
</beans>

package lee;

import org.springframework.context.*;
import org.springframework.context.support.*;

/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class SpringTest
{
    public static void main(String[] args)throws Exception
    {
        ApplicationContext ctx = new
            ClassPathXmlApplicationContext("beans.xml");
        // 下面2行代码获取的FactoryBean的产品
        System.out.println(ctx.getBean("north"));
        System.out.println(ctx.getBean("theValue"));
        // 下面代码可获取的FactoryBean本身
        System.out.println(ctx.getBean("&theValue"));
    }
}

package org.crazyit.app.factory;

import java.lang.reflect.*;
import org.springframework.beans.factory.FactoryBean;
/**
 * Description:
 * <br/>网站: <a href="http://www.crazyit.org">疯狂Java联盟</a>
 * <br/>Copyright (C), 2001-2016, Yeeku.H.Lee
 * <br/>This program is protected by copyright laws.
 * <br/>Program Name:
 * <br/>Date:
 * @author  Yeeku.H.Lee kongyeeku@163.com
 * @version  1.0
 */
public class GetFieldFactoryBean implements FactoryBean<Object>
{
    private String targetClass;
    private String targetField;
    // targetClass的setter方法
    public void setTargetClass(String targetClass)
    {
        this.targetClass = targetClass;
    }

    // targetField的setter方法
    public void setTargetField(String targetField)
    {
        this.targetField = targetField;
    }
    // 返回工厂Bean所生产的产品
    public Object getObject() throws Exception
    {
        Class<?> clazz = Class.forName(targetClass);
        Field field = clazz.getField(targetField);
        return field.get(null);
    }
    // 获取工厂Bean所生产的产品的类型
    public Class<? extends Object> getObjectType()
    {
        return Object.class;
    }
    // 返回该工厂Bean所生成的产品是否为单例
    public boolean isSingleton()
    {
        return false;
    }
}