IOC(六)

注入内部bean

当需要在一个类中使用另一个类中的内容时, 可以按前篇所说的使用注入外部bean的方式:

 除此之外, 还可以使用注入内部bean的方式, 重点在于在xml文件中, 在bean内嵌套bean赋值, 以下例说明:

在Employee类中引入Department类:

Department类:

package com.ryan.spring5.quoteInsideBean;

public class Department {

    private String dname;

    public void setDname(String dname) {
        this.dname = dname;
    }

    @Override
    public String toString() {
        return this.dname;
    }
}

Employee类:

package com.ryan.spring5.quoteInsideBean;

public class Employee {

    private String ename;
    private int eage;
    private Department dept;

    public void setEname(String ename) {
        this.ename = ename;
    }

    public void setEage(int eage) {
        this.eage = eage;
    }

    public void setDept(Department dept) {
        this.dept = dept;
    }

    @Override
    public String toString() {
        return this.dept + " - " + this.ename + " - " + this.eage;
    }
}

***xml配置文件:(重点)

<?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.xsd">

    <!--注入内部bean-->
    <bean id="emp" class="com.ryan.spring5.quoteInsideBean.Employee">
        <property name="ename" value="张辽"></property>
        <property name="eage" value="28"></property>
        <property name="dept">
            <bean id="dept" class="com.ryan.spring5.quoteInsideBean.Department">
                <property name="dname" value="研发部"></property>
            </bean>
        </property>
    </bean>
</beans>

测试:

public class Test {

    public static void main(String[] args) {

        ApplicationContext context = new FileSystemXmlApplicationContext("src\com\ryan\spring5\quoteInsideBean\bean.xml");
        Employee emp = context.getBean("emp", Employee.class);

        System.out.println(emp);
    }
}

结果:

级联赋值

级联赋值即在前篇所说的注入外部bean的基础上, 可以通过对象.属性的方式直接注入属性, 可以修改上例来演示说明:

修改xml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.xsd">

    <!--注入内部bean-->
    <bean id="emp" class="com.ryan.spring5.quoteInsideBean.Employee">
        <property name="ename" value="张辽"></property>
        <property name="eage" value="28"></property>
        <property name="dept" ref="dept"> </property>
        <!--直接注入属性-->
        <property name="dept.dname" value="人力资源部"></property>
    </bean>
    <bean id="dept" class="com.ryan.spring5.quoteInsideBean.Department"></bean>

</beans>

需要dname可获取, 所以需要为Employee添加dept的get方法:

package com.ryan.spring5.quoteInsideBean;

public class Employee {

    private String ename;
    private int eage;
    private Department dept;

    //使用级联赋值必须要有get方法
    public Department getDept() {
        return dept;
    }


    public void setEname(String ename) {
        this.ename = ename;
    }

    public void setEage(int eage) {
        this.eage = eage;
    }

    public void setDept(Department dept) {
        this.dept = dept;
    }

    @Override
    public String toString() {
        return this.dept + " - " + this.ename + " - " + this.eage;
    }
}

测试结果: