Learn Spring - Bean配置继承(配置重用)

Posted Jan 19, 2018

关于Bean配置继承

为了Bean配置的复用，Spring中有Bean配置继承的概念。通过parent属性标识从哪个Bean继承配置信息。类似于面向对象里的概念，子Bean可以覆盖父Bean的配置。还可以设置Bean配置的 abstract属性为true，将该Bean设置为一个模板，其它Bean继承它的模板配置。类似于Java中的抽象类，abstract的Bean不允许实例化。

Example

目录结构

project_tree

Code

Beans.xml

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

<beans xmlns = "http://www.springframework.org/schema/beans"
       xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
       xsi:schemaLocation = "http://www.springframework.org/schema/beans
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd">

    <bean id = "helloWorld" class = "me.coolcodes.HelloWorld">
        <property name = "message1" value = "Message1"/>
        <property name = "message2" value = "Message2"/>
    </bean>

    <bean id="helloSpring" class="me.coolcodes.HelloSpring" parent="helloWorld">
        <property name = "message3" value = "Message3"/>
        <property name = "message4" value="Message4"></property>
    </bean>

</beans>

helloSpring继承了helloWorld的配置（即message1 和 message2)

HelloWorld.java

package me.coolcodes;

public class HelloWorld{
    private String message1;
    private String message2;

    public void setMessage1(String message){
        this.message1  = message;
    }

    public void setMessage2(String message){
        this.message2  = message;
    }

    public void getMessage1(){
        System.out.println("World Message : " + message1);
    }

    public void getMessage2(){
        System.out.println("World Message : " + message2);
    }
}

HelloSpring.java

package me.coolcodes;

public class HelloSpring {
    private String message1;
    private String message2;
    private String message3;
    private String message4;

    public void setMessage1(String message){
        this.message1  = message;
    }

    public void setMessage2(String message){
        this.message2  = message;
    }

    public void setMessage3(String message){
        this.message3  = message;
    }

    public void setMessage4(String message){
        this.message4  = message;
    }

    public void getMessage1(){
        System.out.println("Spring Message : " + message1);
    }

    public void getMessage2(){
        System.out.println("Spring Message : " + message2);
    }

    public void getMessage3(){
        System.out.println("Spring Message : " + message3);
    }

    public void getMessage4(){
        System.out.println("Spring Message : " + message4);
    }
}

Main.java

package me.coolcodes;

import org.springframework.context.support.AbstractApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Main {
    public static void main(String[] args) {
        AbstractApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");
        HelloWorld objA = (HelloWorld) context.getBean("helloWorld");
        HelloSpring objB = (HelloSpring) context.getBean("helloSpring");

        objA.getMessage1();
        objA.getMessage2();

        objB.getMessage1();
        objB.getMessage2();
        objB.getMessage3();
        objB.getMessage4();
    }
}

分别输出HelloWorld的message1 和 message2。HelloSpring的message1、message2、message3、message4。

结果

result

HelloSpring的message1和message2的值继承自HelloWorld。