spring AOP Bean添加新方法

目的：为studentAdditionalDetails中添加Student的showDetails（）和ExtraShowDetails（）两个方法

spring  中AOP能够为现有的方法添加额外的功能，AOP也能为Spring Bean添加新方法

<aop:declare-parents  
　　　　　　types-matching="之前原始的类/接口"
　　　　　　implement-interface="想要添加的功能的接口"
　　　　　　defalut-impl="新功能的默认的实现"
/>

或者：

<aop:declare-parents
　　　　　　types-matching="之前原始的类/接口"
　　　　　　implement-interface="想要添加的功能的接口"
　　　　　　delegate-ref="新功能的默认的实现"
/>

配置文件：

 <?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:aop="http://www.springframework.org/schema/aop"
         xmlns:tx="http://www.springframework.org/schema/tx"
         xmlns:p="http://www.springframework.org/schema/p"
         xsi:schemaLocation="
             http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
             http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
             http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

      <!-- 为StudentAdditionalDetails或者StudentAdditionalDetailsImpl添加student里面的方法 -->
      <bean id="student" class="imple.StudentImpl">
         <property name="studentNo" value="1001" />
         <property name="studentName" value="John Peter" />
     </bean>  

     <bean id="studentAdditionalDetailsImpl" class="imple.StudentAdditionalDetailsImpl">
         <property name="city" value="Newyork" />
         <property name="country" value="America" />
     </bean>  

     <aop:config>
         <aop:aspect>
                                 <!-- types-matching="imple.StudentAdditionalDetailsImpl+"  改成下面的方式 实现的效果相同
                                       说明：types-matching既可以是实现类也可以是接口
                                  -->
             <aop:declare-parents types-matching="inter.StudentAdditionalDetails+"
                                  implement-interface="inter.Student"
                                  delegate-ref="student" />
         </aop:aspect>
     </aop:config>  

 </beans>

或者：

<?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:aop="http://www.springframework.org/schema/aop"
        xmlns:tx="http://www.springframework.org/schema/tx"
        xmlns:p="http://www.springframework.org/schema/p"
        xsi:schemaLocation="
            http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5.xsd
            http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop-2.5.xsd
            http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-2.5.xsd">

     <!-- 为StudentAdditionalDetails或者StudentAdditionalDetailsImpl添加student里面的方法 -->
     <bean id="student" class="imple.StudentImpl">
        <property name="studentNo" value="1001" />
        <property name="studentName" value="John Peter" />
    </bean>  

    <bean id="studentAdditionalDetails" class="imple.StudentAdditionalDetailsImpl">
        <property name="city" value="Newyork" />
        <property name="country" value="America" />
    </bean>  

    <aop:config>
        <aop:aspect>
                                <!-- types-matching="imple.StudentAdditionalDetailsImpl+"  改成下面的方式 实现的效果相同
                                      说明：types-matching既可以是实现类也可以是接口
                                 -->
            <aop:declare-parents types-matching="inter.StudentAdditionalDetails+"
                                 implement-interface="inter.Student"
                                 default-impl="imple.StudentImpl"
                                 />
        </aop:aspect>
    </aop:config>  

</beans>

注意：若采用

default-impl="imple.StudentImpl"

输出结果：不知道为何没有取到值？

1 StudentImpl showDetails studentNo :0
2 StudentImpl showDetails studentName :null
3 StudentImpl ExtraShowDetails studentNo :0
4 StudentImpl ExtraShowDetails studentName :null
5 StudentAdditionalDetailsImpl showAdditionalDetails() city:Newyork
6 StudentAdditionalDetailsImpl showAdditionalDetails() country:America

接口：

 package inter;

 public interface StudentAdditionalDetails {
     public void showAdditionalDetails();
 }  

 package inter;

 public interface Student {
     public void showDetails();
     public void ExtraShowDetails();
 }

实现方法：

package imple;

import inter.StudentAdditionalDetails;

public class StudentAdditionalDetailsImpl implements StudentAdditionalDetails {
    private String city;
    private String country;  

    public String getCity() {
        return city;
    }
    public void setCity(String city) {
        this.city = city;
    }
    public String getCountry() {
        return country;
    }
    public void setCountry(String country) {
        this.country = country;
    }  

    public void showAdditionalDetails(){
        System.out.println("StudentAdditionalDetailsImpl showAdditionalDetails() city:"+this.city);
        System.out.println("StudentAdditionalDetailsImpl showAdditionalDetails() country:"+this.country);
    }
}

 package imple;

 import inter.Student;

 public class StudentImpl implements Student {
     private int studentNo;
     private String studentName;  

     public int getStudentNo() {
         return studentNo;
     }
     public void setStudentNo(int studentNo) {
         this.studentNo = studentNo;
     }
     public String getStudentName() {
         return studentName;
     }
     public void setStudentName(String studentName) {
         this.studentName = studentName;
     }     

     public void showDetails(){
         System.out.println("StudentImpl showDetails studentNo :"+this.studentNo);
         System.out.println("StudentImpl showDetails studentName :"+this.studentName);
     }
     public void ExtraShowDetails() {
         System.out.println("StudentImpl ExtraShowDetails studentNo :"+this.studentNo);
         System.out.println("StudentImpl ExtraShowDetails studentName :"+this.studentName);
     }
 }  

测试方法：

/*
* 基于xml 切面引入性能（为已经实现的类添加新的方法）
* Aop 常见的作用是为现有的方法添加新的功能，该测试方法可以通过Aop为Spring Bean添加新方法
*/

     @Test
     public void test9(){
         StudentAdditionalDetails studentAdditionalDetails = (StudentAdditionalDetails) ctx.getBean("studentAdditionalDetailsImpl");
         ((Student) studentAdditionalDetails).showDetails();
         ((Student) studentAdditionalDetails).ExtraShowDetails();
         studentAdditionalDetails.showAdditionalDetails();
     }

输出结果：

 StudentImpl showDetails studentNo :1001
 StudentImpl showDetails studentName :John Peter
 StudentImpl ExtraShowDetails studentNo :1001
 StudentImpl ExtraShowDetails studentName :John Peter
 StudentAdditionalDetailsImpl showAdditionalDetails() city:Newyork
 StudentAdditionalDetailsImpl showAdditionalDetails() country:America

--------------------------------------------------------以下基于注解实现-----------------------------------------------------------------------------

@DeclareParents(
    value=" AspectJ语法类型表达式",
    defaultImpl=引入接口的默认实现类)
private Interface interface;