Spring深入淺出(十),註解,@Qualifier
阿新 • • 發佈:2021-07-13
可能會有這樣一種情況,當你建立多個具有相同型別的 bean 時,並且想要用一個屬性只為它們其中的一個進行裝配,在這種情況下,你可以使用@Qualifier註釋和@Autowired註釋通過指定哪一個真正的 bean 將會被裝配來消除混亂。
一、建立實體Bean
package com.clzhang.spring.demo; public class Student { private Integer age; private String name; public void setAge(Integer age) { this.age = age; }public Integer getAge() { return age; } public void setName(String name) { this.name = name; } public String getName() { return name; } }
二、建立業務邏輯層
package com.clzhang.spring.demo; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.beans.factory.annotation.Qualifier;public class Profile { @Autowired @Qualifier("student2") private Student student; public Profile() { System.out.println("Inside Profile constructor."); } public void printAge() { System.out.println("Age : " + student.getAge()); } public void printName() { System.out.println("Name : " + student.getName()); } }
三、建立主程式
package com.clzhang.spring.demo; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; public class MainApp { public static void main(String[] args) { ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml"); Profile profile = (Profile) context.getBean("profile"); profile.printAge(); profile.printName(); } }
四、配置檔案如下
<?xml version="1.0" encoding="UTF-8"?> <beans xmlns="http://www.springframework.org/schema/beans" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context" xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.0.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.0.xsd"> <context:annotation-config/> <!-- Definition for profile bean --> <bean id="profile" class="com.clzhang.spring.demo.Profile"> </bean> <!-- Definition for student1 bean --> <bean id="student1" class="com.clzhang.spring.demo.Student"> <property name="name" value="Zara" /> <property name="age" value="11"/> </bean> <!-- Definition for student2 bean --> <bean id="student2" class="com.clzhang.spring.demo.Student"> <property name="name" value="Nuha" /> <property name="age" value="2"/> </bean> </beans>
五、執行
Inside Profile constructor.
Age : 2
Name : Nuha
本文參考:
https://www.w3cschool.cn/wkspring/knqr1mm2.html