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Spring复习:(59)@Qualifier注解


@Qualifier注解用来指定自动注入时合作bean需要满足的qualifier的名称,如果一个bean没有指定qualifier属性,则用它的id为qualifier,来给别的bean提供注入。
示例

package cn.edu.tju.domain;

public class MovieCatalog {
}

package cn.edu.tju.domain;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

public class MovieRecommender {
    @Autowired
    @Qualifier("secondary")
    private MovieCatalog movieCatalog;

}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:mvc="http://www.springframework.org/schema/mvc"
       xmlns:context="http://www.springframework.org/schema/context"
       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
    http://www.springframework.org/schema/mvc
    http://www.springframework.org/schema/mvc/spring-mvc.xsd
    http://www.springframework.org/schema/context
    http://www.springframework.org/schema/context/spring-context.xsd">

    <context:annotation-config/>
    <bean id = "main" class="cn.edu.tju.domain.MovieCatalog">
        <qualifier value="secondary"/>
    </bean>
    <bean id="recommender" class="cn.edu.tju.domain.MovieRecommender">

    </bean>


</beans>

package cn.edu.tju.test;

import cn.edu.tju.domain.People;
import cn.edu.tju.domain.Person;
import com.alibaba.druid.pool.DruidDataSource;
import com.alibaba.druid.pool.DruidPooledConnection;
import org.springframework.context.ConfigurableApplicationContext;
import org.springframework.context.annotation.ConfigurationClassPostProcessor;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import java.sql.SQLException;

public class Test09 {
    public static void main(String[] args) throws Exception {
        ConfigurableApplicationContext ctx = new
                ClassPathXmlApplicationContext("spring9.xml");

    }
}

##########################################################

package cn.edu.tju.domain;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

public class MovieRecommender2 {

    private  MovieCatalog movieCatalog;

    public MovieCatalog getMovieCatalog() {
        return movieCatalog;
    }

    public void setMovieCatalog(MovieCatalog movieCatalog) {
        this.movieCatalog = movieCatalog;
    }

    @Autowired
    public void prepare(@Qualifier("secondary") MovieCatalog movieCatalog) {
        this.movieCatalog = movieCatalog;
    }

}


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