spring 引用其他Bean

spring ioc 容器中定义的Bean 可以相互引用，Ioc 充当媒介的作用。

比如创建一个一个word 类，将Car,People 等作为他的属性。

public class World {

    private Car car ;

    private People people ;

    private String good ;

    public World(Car car, People people, String good) {

      super ();

      this . car = car;

      this . people = people;

      this . good = good;

    }

    public Car getCar() {

      return car ;

    }

    public void setCar(Car car) {

      this . car = car;

    }

    public People getPeople() {

      return people ;

    }

    public void setPeople(People people) {

      this . people = people;

    }

    public String getGood() {

      return good ;

    }

    public void setGood(String good) {

      this . good = good;

    }

}

如何在配置文件中装配Car 和People 这两个类呢？

首先要声明People和Car这两个Bean

      <!-- 构造函数中的 联合入参方法   -->

           < bean id = "people" class = "com.modle.People" >

               < constructor-arg type = "String" index = "0" >< value > 光头墙 </ value ></ constructor-arg >

               < constructor-arg type = "String" index = "1" > < value > 狗熊森林 </ value ></ constructor-arg >

               < constructor-arg type = "int" index = "2" >< value > 60 </ value ></ constructor-arg >

           </ bean >

     

     <!-- 属性注入方法 -->

      < bean id = "car" class = "com.modle.Car" >

                    < property name = "brand" >< value > 红旗 </ value ></ property >

                    < property name = "price" >< value > 12 </ value ></ property >

      </ bean >

第二步：引入上面声明的两个Bean

<!--构造函数注入 通过自身反射入参 -->

           < bean id = "world" class = "com.modle.World" >

                < constructor-arg >< value > hello </ value ></ constructor-arg >

               < constructor-arg >< ref bean = "car" ></ ref ></ constructor-arg > <!-- 注入上面的bean -->

               < constructor-arg >< ref bean = "people" ></ ref ></ constructor-arg >

           </ bean >

说明：1、Car的声明用的属性注入法

          People用的构造函数注入的联合入参法（通过参数类型和参数索引联合匹配参数）

          World的声明使用自身反射来入参，引入Bean.

         2、<ref>标签有三个属性 分别是 bean local parent .bean是引用本容器或父容器的配置。优先引用本容器。local 是只引用本容器 。parent是只引用父容器。