spring关于@Autowired和@Qualifier的使用

//

package com.jhc.model;

import org.springframework.stereotype.Component;

@Component
public interface ModelTest3 {
    void sayHello();
}

//

package com.jhc.model;

import org.springframework.stereotype.Component;

@Component
public class ModelTest3_1 implements ModelTest3 {

    @Override
    public void sayHello() {
        System.out.println("hello word modelTest3_1");
    }
}

//

package com.jhc.model;

import org.springframework.stereotype.Component;

@Component
public class ModelTest3_2 implements ModelTest3 {
    @Override
    public void sayHello() {
        System.out.println("hello word modelTest3_2");
    }
}

//

package com.jhc.model;

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

@Component
public class TestModelTest3 {

    @Autowired
    @Qualifier("modelTest3_1")
    private ModelTest3 modelTest3=null;


    public void sayHello(){
        modelTest3.sayHello();
    }

}

//@Qualifier("modelTest3_1")处的参数一定要与实现类的名字相同，且首字母小写

package com.jhc.test;

//import com.jhc.model.PojoConfig;
import com.jhc.model.TestModelTest3;
import org.springframework.context.ApplicationContext;
//import org.springframework.context.annotation.AnnotationConfigApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class Test3 {
    public static void main(String[] args){
        //ApplicationContext applicationContext=new AnnotationConfigApplicationContext(PojoConfig.class);
        ApplicationContext applicationContext=new ClassPathXmlApplicationContext("spring-config.xml");
        TestModelTest3 testModelTest3=applicationContext.getBean(TestModelTest3.class);
        testModelTest3.sayHello();
    }
}

//上面第11行与第12行是两种方法，二选一，如果采用第11行处方法就添加如下代码（注意取消注释），此时可以删除XML文件的第19行代码，注意XML第19行的扫描范围，和下面被注释代码的包名

/*package com.jhc.model;

import org.springframework.context.annotation.ComponentScan;

@ComponentScan
public class PojoConfig {
}*/

 

<?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.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context.xsd
 ">
    <!--数据源配置-->
    <!--<bean id="dataSource" class="org.springframework.jdbc.datasource.SimpleDriverDataSource">
        <property name="url" value="jdbc:mysql://localhost:3306/study2"/>
        <property name="driver" value="com.mysql.jdbc.Driver"/>
        <property name="username" value="root"/>
        <property name="password" value="mysql"/>
    </bean>-->
    <!--扫描com.jhc包路径下的类-->
    <context:component-scan base-package="com.jhc"></context:component-scan>

    <!--第三方数据库连接池-->
    <!--<bean id="dataSource" class="org.apache.commons.dbcp2.BasicDataSource">
        <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
        <property name="url" value="jdbc:mysql://localhost:3306/study2"/>
        <property name="username" value="root"/>
        <property name="password" value="mysql"/>
        最大连接数
        最大等待连接中的数量
        最大等待毫秒数
        <property name="maxTotal" value="255"/>
        <property name="maxIdle" value="5"/>
        <property name="maxWaitMillis" value="10000"/>
    </bean>-->


    <!--jdbcTemplate-->
    <!--<bean id="jdbcTemplate" class="org.springframework.jdbc.core.JdbcTemplate">
        <property name="dataSource" ref="dataSource"/>
    </bean>-->


</beans>

//运行结果是

hello word modelTest3_1

 

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