Java Spring study notes - Bean dependency injection (1)

There are two commonly used dependency injection methods in Spring: one is the set-value injection method, which uses the bean's setter method to set the property value of the bean; the other is the construction injection, which implements the assignment of the bean's properties by passing parameters to the bean's construction method;

1. Set value injection method

Go directly to the code example, the tree structure diagram of the example is as follows

 Shape.java interface content

package chapter3;

public  interface Shape {
     public  double area(); // Find the area of ​​the shape 
}    

Circle.java content:

package chapter3;

public class Circle implements Shape {

    double r;
    public double getR(){
        return this.r;
    }
    public void setR(double r){
        this.r=r;
    }
    
    @Override
    public double area() {
        // TODO Auto-generated method stub
        return Math.PI*Math.pow(r, 2);
    }

}

Rectangle.java content

package chapter3;

public class Rectangle implements Shape {

    double width,height;
    
    public double getWidth(){
        return this.width;
    }
    public void setWidth(double width){
        this.width=width;
    }
    
    public double getHeight(){
        return this.height;
    }
    public void setHeight(double height){
        this.height=height;
    }
    
    @Override
    public double area() {
        // TODO Auto-generated method stub
        return width*height;
    }

}

AnyShape.java content

package chapter3;

public class AnyShape {
    Shape shape;
    public void setShape(Shape shape) {this.shape=shape;}
    public Shape getShape(){return this.shape;}
    public void outputArea(){
        System.out.println("面积="+shape.area());
    }
}

 

Test.java content

package chapter3;

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

public class Test {

    /**
     * @param args
     */
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ApplicationContext context=new FileSystemXmlApplicationContext("src/myContext.xml");
        AnyShape shape=(AnyShape)context.getBean("anyShape");
        shape.outputArea();
        
        AnyShape shape2=(AnyShape)context.getBean("anyShape2");
        shape2.outputArea();
    }

}

xml configuration file

<?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-2.5.xsd">
           
           <bean id="myShape" class="chapter3.Circle">
           <property name="R">
           <value>2.5</value>
           </property>
           </bean>
           
           <bean id="myShape2" class="chapter3.Rectangle">
           <property name="height">
           <value>2</value>
           </property>
           <property name="width">
           <value>5</value>
           </property>
           </bean>
           
           <bean id="anyShape" class="chapter3.AnyShape">
           <property name="shape">
           <ref bean="myShape"/>
           </property>
           </bean>
           
            <bean id="anyShape2" class="chapter3.AnyShape">
           <property name="shape">
           <ref bean="myShape2"/>
           </property>
           </bean>

</beans>