Spring中引用标签ref和属性ref

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ref作为属性

<bean id="students" class="com.yiwen.Students">    <property name="group" ref="group"></bean><bean id="group" class="com.yiwen.Group" />

ref作为标签

local=”group” 表示在该xml文件中查找group（Spring4.0 没有local属性了，它的作用其实和ref属性一样，用属性也行）

<bean id="students" class="com.yiwen.Students">    <property name="group" >        <ref local="group">    </property></bean><bean id="group" class="com.yiwen.Group">

bean=”group” 表示全局查找id为group的bean,可在不同的xml中查找group
spring-main.xml
```
```<bean id="students" class="com.yiwen.Students">    <property name="group" >        <ref bean="group">    </property></bean>```
```
spring-part.xml
```
<bean id="group" class="com.yiwen.Group">
```
这样spring-main.xml中一样可以找到spring-part.xml中的id为group的bean

使用ref标签的实例

虽然直接使用ref属性非常简单方便，但是有时候xml文件存在多个，利用bean,不管在不在一个xml文件中都可以识别到。
编写三个类School 和Students Teachers
Teachers

public class Teachers {    private String name;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

Students

public class Students {    private String name ;    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }}

School

public class School {    private Students students;    private Teachers teachers;    public School(Students students, Teachers teachers) {        this.students = students;        this.teachers = teachers;    }    public Students getStudents() {        return students;    }    public Teachers getTeachers() {        return teachers;    }}

配置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">    <bean id="school" class="com.yiwen.test6.School">        <constructor-arg name="students">            <ref bean="students"></ref>        </constructor-arg>        <constructor-arg name="teachers">            <ref bean="teachers"></ref>        </constructor-arg>    </bean>    <bean id="students" class="com.yiwen.test6.Students" >        <property name="name">            <value type="java.lang.String">yiwen</value>        </property>    </bean>    <bean id="teachers" class="com.yiwen.test6.Teachers">        <property name="name">            <value type="java.lang.String">zhangsan</value>        </property>    </bean></beans>

测试类

import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class App {    public static void main(String[] args) {        ApplicationContext context=new ClassPathXmlApplicationContext("test6.xml");        School school=(School)context.getBean("school");        System.out.print("student name:"+school.getStudents().getName()+"teacher name :"+school.getTeachers().getName());    }}

结果如下所示：

student name:yiwenteacher name :zhangsan

表明Students和Teacher的bean已经装配到了School中了。

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