Spring实战——使用静态工厂方法创建Bean

清疚 2021-07-24 12:55 334阅读 0赞

**一 配置**

<?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">
         
         <bean id="dog"  class="org.crazyit.app.factory.BeingFactory"
               factory-method="getBeing">
               
               <constructor-arg value="dog"/>
               
               <property name="msg" value="我是狗"/>
         </bean>
         
         <bean id="cat"  class="org.crazyit.app.factory.BeingFactory"
               factory-method="getBeing">
               
               <constructor-arg value="cat"/>
               
               <property name="msg" value="我是猫"/>
         </bean>
    </beans>

**二 接口**

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

**三 实现类**

1 Cat

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;
         }
         // 实现接口必须实现的testBeing方法
         public void testBeing()
         {
               System.out.println(msg +
                    "，猫喜欢吃老鼠");
         }
    }

2 Dog

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;
         }
         // 实现接口必须实现的testBeing()方法
         public void testBeing()
         {
               System.out.println(msg +
                    "，狗爱啃骨头");
         }
    }

**四 工厂类**

package org.crazyit.app.factory;
    
    
    import org.crazyit.app.service.impl.*;
    import org.crazyit.app.service.*;
    
    public class BeingFactory
    {
        // 返回Being实例的静态工厂方法
        // arg参数决定返回哪个Being类的实例
        public static Being getBeing(String arg)
        {
            // 调用此静态方法的参数为dog，则返回Dog实例
            if (arg.equalsIgnoreCase("dog"))
            {
                return new Dog();
            }
            // 否则返回Cat实例
            else
            {
                return new Cat();
            }
        }
    }

**五 测试类**

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)
        {
            // 以类加载路径下的配置文件创建ClassPathResource实例
            ApplicationContext ctx = new
                ClassPathXmlApplicationContext("beans.xml");
            Being b1 = ctx.getBean("dog" , Being.class);
            b1.testBeing();
            Being b2 = ctx.getBean("cat" , Being.class);
            b2.testBeing();
        }
    }

**六 测试结果**

我是狗，狗爱啃骨头
    我是猫，猫喜欢吃老鼠