Spring實(shí)戰(zhàn)之使用靜態(tài)工廠方法創(chuàng)建Bean操作示例

<?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">
   <!-- 下面配置驅(qū)動(dòng)Spring調(diào)用BeingFactory的靜態(tài)getBeing()方法來創(chuàng)建Bean
   該bean元素包含的constructor-arg元素用于為靜態(tài)工廠方法指定參數(shù)，
   因此這段配置會(huì)驅(qū)動(dòng)Spring以反射方式來執(zhí)行如下代碼：
   dog = org.crazyit.app.factory.BeingFactory.getBeing("dog"); -->
   <bean id="dog" class="org.crazyit.app.factory.BeingFactory"
      factory-method="getBeing">
      <!-- 配置靜態(tài)工廠方法的參數(shù) -->
      <constructor-arg value="dog"/>
      <!-- 驅(qū)動(dòng)Spring以"我是狗"為參數(shù)來執(zhí)行dog的setMsg()方法 -->
      <property name="msg" value="我是狗"/>
   </bean>
   <!-- 下面配置會(huì)驅(qū)動(dòng)Spring以反射方式來執(zhí)行如下代碼：
   dog = org.crazyit.app.factory.BeingFactory.getBeing("cat"); -->
   <bean id="cat" class="org.crazyit.app.factory.BeingFactory"
      factory-method="getBeing">
      <!-- 配置靜態(tài)工廠方法的參數(shù) -->
      <constructor-arg value="cat"/>
      <!-- 驅(qū)動(dòng)Spring以"我是貓"為參數(shù)來執(zhí)行dog的setMsg()方法 -->
      <property name="msg" value="我是貓"/>
   </bean>
</beans>

package org.crazyit.app.service;
public interface Being
{
   public void testBeing();
}

package org.crazyit.app.service.impl;
import org.crazyit.app.service.*;
public class Cat implements Being
{
   private String msg;
   // msg的setter方法
   public void setMsg(String msg)
   {
      this.msg = msg;
   }
   // 實(shí)現(xiàn)接口必須實(shí)現(xiàn)的testBeing方法
   public void testBeing()
   {
      System.out.println(msg +
        "，貓喜歡吃老鼠");
   }
}

package org.crazyit.app.service.impl;
import org.crazyit.app.service.*;
public class Dog implements Being
{
   private String msg;
   // msg的setter方法
   public void setMsg(String msg)
   {
      this.msg = msg;
   }
   // 實(shí)現(xiàn)接口必須實(shí)現(xiàn)的testBeing()方法
   public void testBeing()
   {
      System.out.println(msg +
        "，狗愛啃骨頭");
   }
}

package org.crazyit.app.factory;
import org.crazyit.app.service.impl.*;
import org.crazyit.app.service.*;
public class BeingFactory
{
  // 返回Being實(shí)例的靜態(tài)工廠方法
  // arg參數(shù)決定返回哪個(gè)Being類的實(shí)例
  public static Being getBeing(String arg)
  {
    // 調(diào)用此靜態(tài)方法的參數(shù)為dog，則返回Dog實(shí)例
    if (arg.equalsIgnoreCase("dog"))
    {
      return new Dog();
    }
    // 否則返回Cat實(shí)例
    else
    {
      return new Cat();
    }
  }
}

package lee;
import org.springframework.context.*;
import org.springframework.context.support.*;
import org.crazyit.app.service.*;
public class SpringTest
{
  public static void main(String[] args)
  {
    // 以類加載路徑下的配置文件創(chuàng)建ClassPathResource實(shí)例
    ApplicationContext ctx = new
      ClassPathXmlApplicationContext("beans.xml");
    Being b1 = ctx.getBean("dog" , Being.class);
    b1.testBeing();
    Being b2 = ctx.getBean("cat" , Being.class);
    b2.testBeing();
  }
}