Spring常用的两种依赖注入方式：一种是设值注入方式，利用Bean的setter方法设置Bean的属性值；另一种是构造注入，通过给Bean的构造方法传递参数来实现Bean的属性赋值；
1、设值注入方式
直接上代码例子，示例的树结构图如下
Shape.java接口内容
package chapter3;
public interface Shape {
public double area();//求形状的面积
}
Circle.java内容：
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, );
}
}
Rectangle.java内容
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内容
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内容
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配置文件
<?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></value>
</property>
<property name="width">
<value></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>
在配置文件中，每个Bean的id属性定义Bean的标识。查找和引用Bean是通过该标识进行的。Bean的class属性顶了Bean对应的类和路径名称。通过Bean的子元素property实现属性值的设置，它是通过调用相应属性的setter方法实现属性值的注入。标识为“anyshape”的Bean在设置shape的属性时通过<ref/>标签引用了标识为“myshape”的bean,也就是shape属性由标识为“myshape”的Bean决定的。