9.3.Spring 中基于 AOP 的 XML架构

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（以下内容引用自https://www.w3cschool.cn/wkspring/omps1mm6.html）

Spring 中基于 AOP 的 XML架构

为了在本节的描述中使用 aop 命名空间标签，你需要导入 spring-aop j架构，如下所述：

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">   <!-- bean definition & AOP specific configuration --></beans>

你还需要在你的应用程序的 CLASSPATH 中使用以下 AspectJ 库文件。这些库文件在一个 AspectJ 装置的 ‘lib’ 目录中是可用的，否则你可以在 Internet 中下载它们。

aspectjrt.jar
aspectjweaver.jar
aspectj.jar
aopalliance.jar

声明一个 aspect

一个 aspect 是使用元素声明的，支持的 bean 是使用 ref 属性引用的，如下所示：

<aop:config>   <aop:aspect id="myAspect" ref="aBean">   ...   </aop:aspect></aop:config><bean id="aBean" class="...">...</bean>

这里，“aBean” 将被配置和依赖注入，就像前面的章节中你看到的其他的 Spring bean 一样。

声明一个切入点

一个切入点有助于确定使用不同建议执行的感兴趣的连接点（即方法）。在处理基于配置的 XML 架构时，切入点将会按照如下所示定义：

<aop:config>   <aop:aspect id="myAspect" ref="aBean">   <aop:pointcut id="businessService"   expression="execution(* com.xyz.myapp.service.*.*(..))"/>   ...   </aop:aspect></aop:config><bean id="aBean" class="...">...</bean>

下面的示例定义了一个名为 “businessService” 的切入点，该切入点将与 com.tutorialspoint 包下的 Student 类中的 getName() 方法相匹配：

<aop:config>   <aop:aspect id="myAspect" ref="aBean">   <aop:pointcut id="businessService"  expression="execution(* com.tutorialspoint.Student.getName(..))"/>   ...   </aop:aspect></aop:config><bean id="aBean" class="...">...</bean>

声明建议

你可以使用 <aop:{ADVICE NAME}> 元素在一个中声明五个建议中的任何一个，如下所示：

<aop:config>   <aop:aspect id="myAspect" ref="aBean">      <aop:pointcut id="businessService"         expression="execution(* com.xyz.myapp.service.*.*(..))"/>      <!-- a before advice definition -->      <aop:before pointcut-ref="businessService"          method="doRequiredTask"/>      <!-- an after advice definition -->      <aop:after pointcut-ref="businessService"          method="doRequiredTask"/>      <!-- an after-returning advice definition -->      <!--The doRequiredTask method must have parameter named retVal -->      <aop:after-returning pointcut-ref="businessService"         returning="retVal"         method="doRequiredTask"/>      <!-- an after-throwing advice definition -->      <!--The doRequiredTask method must have parameter named ex -->      <aop:after-throwing pointcut-ref="businessService"         throwing="ex"         method="doRequiredTask"/>      <!-- an around advice definition -->      <aop:around pointcut-ref="businessService"          method="doRequiredTask"/>   ...   </aop:aspect></aop:config><bean id="aBean" class="...">...</bean>

你可以对不同的建议使用相同的 doRequiredTask 或者不同的方法。这些方法将会作为 aspect 模块的一部分来定义。

基于 AOP 的 XML 架构的示例

1.结构目录

2.代码

Logging.java(实际上是 aspect 模块的一个示例，它定义了在各个点调用的方法。)

package com.tutorialspoint;public class Logging {   /**     * This is the method which I would like to execute    * before a selected method execution.    */   public void beforeAdvice(){      System.out.println("Going to setup student profile.");   }   /**     * This is the method which I would like to execute    * after a selected method execution.    */   public void afterAdvice(){      System.out.println("Student profile has been setup.");   }   /**     * This is the method which I would like to execute    * when any method returns.    */   public void afterReturningAdvice(Object retVal){      System.out.println("Returning:" + retVal.toString() );   }   /**    * This is the method which I would like to execute    * if there is an exception raised.    */   public void AfterThrowingAdvice(IllegalArgumentException ex){      System.out.println("There has been an exception: " + ex.toString());      }  }

Student.java

package com.tutorialspoint;public class Logging {   /**     * This is the method which I would like to execute    * before a selected method execution.    */   public void beforeAdvice(){      System.out.println("Going to setup student profile.");   }   /**     * This is the method which I would like to execute    * after a selected method execution.    */   public void afterAdvice(){      System.out.println("Student profile has been setup.");   }   /**     * This is the method which I would like to execute    * when any method returns.    */   public void afterReturningAdvice(Object retVal){      System.out.println("Returning:" + retVal.toString() );   }   /**    * This is the method which I would like to execute    * if there is an exception raised.    */   public void AfterThrowingAdvice(IllegalArgumentException ex){      System.out.println("There has been an exception: " + ex.toString());      }  }

MainApp.java

package test;import org.springframework.context.ApplicationContext;import org.springframework.context.support.ClassPathXmlApplicationContext;public class MainApp {   public static void main(String[] args) {      ApplicationContext context = new ClassPathXmlApplicationContext("Beans.xml");      Student student = (Student) context.getBean("student");      student.getName();      student.getAge();            student.printThrowException();   }}

配置文件 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:aop="http://www.springframework.org/schema/aop"    xsi:schemaLocation="http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">   <aop:config>      <aop:aspect id="log" ref="logging">         <aop:pointcut id="selectAll"          expression="execution(* com.tutorialspoint.*.*(..))"/>         <aop:before pointcut-ref="selectAll" method="beforeAdvice"/>         <aop:after pointcut-ref="selectAll" method="afterAdvice"/>         <aop:after-returning pointcut-ref="selectAll"                               returning="retVal"                              method="afterReturningAdvice"/>         <aop:after-throwing pointcut-ref="selectAll"                              throwing="ex"                             method="AfterThrowingAdvice"/>      </aop:aspect>   </aop:config>   <!-- Definition for student bean -->   <bean id="student" class="com.tutorialspoint.Student">      <property name="name"  value="Zara" />      <property name="age"  value="11"/>         </bean>   <!-- Definition for logging aspect -->   <bean id="logging" class="com.tutorialspoint.Logging"/> </beans>

运行Mainapp.java 输出以下消息：

Going to setup student profile.Name : ZaraStudent profile has been setup.Returning:ZaraGoing to setup student profile.Age : 11Student profile has been setup.Returning:11Going to setup student profile.Exception raisedStudent profile has been setup.There has been an exception: java.lang.IllegalArgumentException.....other exception content

让我们来解释一下上面定义的在 com.tutorialspoint 中选择所有方法的。让我们假设一下，你想要在一个特殊的方法之前或者之后执行你的建议，你可以通过替换使用真实类和方法名称的切入点定义中的星号（*）来定义你的切入点来缩短你的执行。

<?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"    xsi:schemaLocation="http://www.springframework.org/schema/beans    http://www.springframework.org/schema/beans/spring-beans-3.0.xsd     http://www.springframework.org/schema/aop     http://www.springframework.org/schema/aop/spring-aop-3.0.xsd ">   <aop:config>   <aop:aspect id="log" ref="logging">      <aop:pointcut id="selectAll"       expression="execution(* com.tutorialspoint.Student.getName(..))"/>      <aop:before pointcut-ref="selectAll" method="beforeAdvice"/>      <aop:after pointcut-ref="selectAll" method="afterAdvice"/>   </aop:aspect>   </aop:config>   <!-- Definition for student bean -->   <bean id="student" class="com.tutorialspoint.Student">      <property name="name"  value="Zara" />      <property name="age"  value="11"/>         </bean>   <!-- Definition for logging aspect -->   <bean id="logging" class="com.tutorialspoint.Logging"/> </beans>

如果你想要执行通过这些更改之后的示例应用程序，这将会输出以下消息：

Going to setup student profile.Name : ZaraStudent profile has been setup.Age : 11Exception raised.....other exception content

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