关于spring:Spring限定注入逻辑分组Qualifier

应用场景

当你创立多个具备雷同类型的 bean 时，并且想要用一个属性只为它们其中的一个进行拆卸，在这种状况下，你能够应用 @Qualifier 正文和 @Autowired 正文通过指定哪一个真正的 bean 将会被拆卸来打消凌乱。上面显示的是应用 @Qualifier 正文的一个示例。

实体类Rumenz/SuperRumenz

package com.rumenz;public class Rumenz{    private Integer id;    private String name;    public Integer getId() {        return id;    }    public void setId(Integer id) {        this.id = id;    }    public String getName() {        return name;    }    public void setName(String name) {        this.name = name;    }    @Override    public String toString() {        return "Rumenz{" +                "id=" + id +                ", name='" + name + '\'' +                '}';    }}package com.rumenz;public class SuperRumenz extends Rumenz {    private String type;    public String getType() {        return type;    }    public void setType(String type) {        this.type = type;    }    @Override    public String toString() {        return "SuperRumenz{" +                "type='" + type + '\'' +                "} " + super.toString();    }}

自定义注解@Grp进行逻辑分组用

package com.rumenz;import org.springframework.beans.factory.annotation.Qualifier;import java.lang.annotation.*;@Target({ElementType.FIELD, ElementType.METHOD, ElementType.PARAMETER, ElementType.TYPE, ElementType.ANNOTATION_TYPE})@Retention(RetentionPolicy.RUNTIME)@Inherited@Documented@Qualifierpublic @interface Grp {}

配置Beans.xml

<?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:util="http://www.springframework.org/schema/util"       xsi:schemaLocation="        http://www.springframework.org/schema/beans https://www.springframework.org/schema/beans/spring-beans.xsd        http://www.springframework.org/schema/util https://www.springframework.org/schema/util/spring-util.xsd">    <bean id="rumenz" class="com.rumenz.Rumenz">        <property name="id" value="123"/>        <property name="name" value="入门小站"/>    </bean>    <bean id="superRumenz" class="com.rumenz.SuperRumenz" parent="rumenz" primary="true">        <property name="id" value="456"/>        <property name="name" value="入门小站-子类"/>        <property name="type" value="1"/>    </bean></beans>

当Spring容器中有多个同一种类型的Bean时,标注为 primary="true" 的Bean将首先被注入应用

@Autowiredprivate  Rumenz rumenz; //rumenz---->SuperRumenz

调用

package com.rumenz;import org.springframework.beans.factory.annotation.Autowired;import org.springframework.beans.factory.annotation.Qualifier;import org.springframework.beans.factory.xml.XmlBeanDefinitionReader;import org.springframework.context.annotation.AnnotationConfigApplicationContext;import org.springframework.context.annotation.Bean;import java.util.Arrays;import java.util.List;public class DemoApplication  {    @Autowired    private  Rumenz rumenz;    @Autowired    @Qualifier("rumenz")    private Rumenz rumenz1;    @Autowired    @Qualifier    private List<Rumenz> list;    @Bean    @Qualifier    public Rumenz rumenz2(){        Rumenz r = new Rumenz();        r.setName("rumenz2");        r.setId(2);        return r;    }    @Bean    @Qualifier    public Rumenz rumenz3(){        Rumenz r = new Rumenz();        r.setName("rumenz3");        r.setId(3);        return r;    }    @Bean    @Grp    public Rumenz rumenz4(){        Rumenz r = new Rumenz();        r.setName("rumenz4");        r.setId(4);        return r;    }    @Bean    @Grp    public Rumenz rumenz5(){        Rumenz r = new Rumenz();        r.setName("rumenz5");        r.setId(5);        return r;    }    @Autowired    @Grp    private List<Rumenz> listGrp;       public static void main(String[] args) {        AnnotationConfigApplicationContext ac=new AnnotationConfigApplicationContext();        XmlBeanDefinitionReader xr=new XmlBeanDefinitionReader(ac);        xr.loadBeanDefinitions("Beans.xml");                ac.register(DemoApplication.class);        ac.refresh();        DemoApplication demoApplication = ac.getBean(DemoApplication.class);        System.out.println(demoApplication.rumenz.getName());        System.out.println(demoApplication.rumenz1.getName());        System.out.println(Arrays.toString(demoApplication.list.toArray()));        System.out.println(Arrays.toString(demoApplication.listGrp.toArray()));        ac.close();    }}

输入

入门小站-子类入门小站[Rumenz{id=2, name='rumenz2'}, Rumenz{id=3, name='rumenz3'}, Rumenz{id=4, name='rumenz4'}, Rumenz{id=5, name='rumenz5'}][Rumenz{id=4, name='rumenz4'}, Rumenz{id=5, name='rumenz5'}]

源码:https://github.com/mifunc/Spr...

原文: https://rumenz.com/rumenbiji/Spring-Qualifier.html