Spring实战——构造注入

桃扇骨 2021-07-24 19:46 497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="chinese"  class="org.crazyit.app.service.impl.Chinese">
               
               <constructor-arg ref="steelAxe"  type="org.crazyit.app.service.Axe"/>
         </bean>
         
         <bean id="stoneAxe"  class="org.crazyit.app.service.impl.StoneAxe"/>
         
         <bean id="steelAxe"  class="org.crazyit.app.service.impl.SteelAxe"/>
    </beans>

**二 接口**

Axe

package org.crazyit.app.service;
    
    public interface Axe
    {
         // Axe接口里有个砍的方法
         public String chop();
    }

Person

package org.crazyit.app.service;
    
    public interface Person
    {
         // 定义一个使用斧子的方法
         public void useAxe();
    }

**三 实现**

Chinese

package org.crazyit.app.service.impl;
    import org.crazyit.app.service.*;
    
    public class Chinese implements Person
    {
         private Axe axe;
         // 构造注入所需的带参数的构造器
         public Chinese(Axe axe)
         {
               this.axe = axe;
         }
         // 实现Person接口的useAxe()方法
         public void useAxe()
         {
               // 调用axe的chop()方法
               // 表明Person对象依赖于axe对象
               System.out.println(axe.chop());
         }
    }

StoneAxe

package org.crazyit.app.service.impl;
    import org.crazyit.app.service.*;
    
    public class StoneAxe implements Axe
    {
         public String chop()
         {
               return "石斧砍柴好慢";
         }
    }

SteelAxe

package org.crazyit.app.service.impl;
    import org.crazyit.app.service.*;
    
    public class SteelAxe implements Axe
    {
         public String chop()
         {
               return "钢斧砍柴真快";
         }
    }

**四 测试类**

package lee;
    
    import org.springframework.context.ApplicationContext;
    import org.springframework.context.support.ClassPathXmlApplicationContext;
    
    import org.crazyit.app.service.*;
    
    public class BeanTest
    {
        public static void main(String[] args)throws Exception
        {
            // 创建Spring容器
            ApplicationContext ctx = new
                ClassPathXmlApplicationContext("beans.xml");
            // 获取chinese 实例
            Person p = ctx.getBean("chinese" , Person.class);
            // 调用useAxe()方法
            p.useAxe();
        }
    }

**五 运行**

钢斧砍柴真快