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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