Spring AOP AspectJ XML 配置示例 - 《HowToDoInJava 中文系列教程》

1）如何声明切面
2）如何定义切入点
3）定义建议
基于 XML 的 Spring AOP 配置的示例应用程序

原文： https://howtodoinjava.com/spring-aop/spring-aop-aspectj-xml-configuration-example/

如果您是仍然对 JDK 1.4 感兴趣的极少数开发人员之一，或者您正在维护一个旧的 Spring 应用程序，其中 AOP 代码已用 XML 配置文件编写，那么此文章适合您。在此处学习如何使用基于 xml 的配置来定义和使用 AspectJ 的 spring aop。

阅读更多内容：使用注解配置的 Spring AOP AspectJ 示例

1）如何声明切面

使用<aop:aspect>元素声明一个切面，并使用ref属性引用该支持 bean，如下所示：

<aop:config>
   <aop:aspect id="loggingAspect" ref="loggingAspectBean">
   ...
   </aop:aspect>
</aop:config>
<bean id="loggingAspectBean" class="com.howtodoinjava.demo.aop.EmployeeCRUDLoggingAspect" />

2）如何定义切入点

切入点有助于确定要使用不同建议执行的连接点。切入点将定义如下：

<aop:config>
   <aop:aspect id="loggingAspect" ref="loggingAspectBean">
        <aop:pointcut id="loggingOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.*(..))" />
        <aop:pointcut id="transactionOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.getEmployeeById(..))" />
   </aop:aspect>
</aop:config>
<bean id="loggingAspectBean" class="com.howtodoinjava.demo.aop.EmployeeCRUDLoggingAspect" />

在上面的示例中，两个切入点（loggingOperation和transactionOperation）将与EmployeeManager类中定义的方法匹配。其中loggingOperation切入点将匹配EmployeeManager中定义的所有方法，而transactionOperation仅匹配EmployeeManager.getEmployeeById()方法执行。

阅读更多内容：Spring AOP AspectJ 切入点表达式以及示例

3）定义建议

您可以使用<aop:advise_name>元素在<aop:aspect>中声明五个建议中的任何一个，如下所示：

<aop:config>
        <!-- Spring AOP Pointcut definitions -->
        <aop:pointcut id="loggingOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.*(..))" />
        <aop:pointcut id="transactionOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.getEmployeeById(..))" />
        <!-- Spring AOP aspect -->
        <aop:aspect id="loggingAspect" ref="loggingAspectBean">
            <!-- Spring AOP advises -->
            <aop:before pointcut-ref="loggingOperation" method="logBefore" />
            <aop:after pointcut-ref="loggingOperation" method="logAfter" />
        </aop:aspect>
    </aop:config>

基于 XML 的 Spring AOP 配置的示例应用程序

在此示例中，我在EmployeeManager接口内定义的所有方法的日志建议之前和之后应用EmployeeManager.getEmployeeById()方法的事务建议。完整的配置文件如下：

applicationContext.xml

<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 ">
    <!-- We don't need to this; This is required only in annotation based AOP support -->
    <!-- <aop:aspectj-autoproxy /> -->
    <aop:config>
        <!-- Spring AOP Pointcut definitions -->
        <aop:pointcut id="loggingOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.*(..))" />
        <aop:pointcut id="transactionOperation"
            expression="execution(* com.howtodoinjava.demo.aop.EmployeeManager.getEmployeeById(..))" />
        <!-- Spring AOP aspect 1 -->
        <aop:aspect id="loggingAspect" ref="loggingAspectBean">
            <!-- Spring AOP advises -->
            <aop:before pointcut-ref="loggingOperation" method="logBefore" />
            <aop:after pointcut-ref="loggingOperation" method="logAfter" />
        </aop:aspect>
        <!-- Spring AOP aspect 2 -->
        <aop:aspect id="transactionAspect" ref="transactionAspectBean">
            <aop:before pointcut-ref="transactionOperation" method="getEmployeeById" />
        </aop:aspect>
    </aop:config>
    <!-- Spring AOP aspect instances -->
    <bean id="loggingAspectBean" class="com.howtodoinjava.demo.aop.EmployeeCRUDLoggingAspect" />
    <bean id="transactionAspectBean" class="com.howtodoinjava.demo.aop.EmployeeCRUDTransactionAspect" />
    <!-- Target Object -->
    <bean id="employeeManager" class="com.howtodoinjava.demo.aop.EmployeeManagerImpl" />
</beans>

本示例中使用的其他文件是：

EmployeeDTO.java

public class EmployeeDTO {
    private Integer id;
    private String firstName;
    private String lastName;
    //Setters and Getters
}

EmployeeManager.java

public interface EmployeeManager 
{
    public EmployeeDTO getEmployeeById(Integer employeeId);
    public List<EmployeeDTO> getAllEmployee();
    public void createEmployee(EmployeeDTO employee);
    public void deleteEmployee(Integer employeeId);
    public void updateEmployee(EmployeeDTO employee);
}

EmployeeManagerImpl.java

public class EmployeeManagerImpl implements EmployeeManager
{
    public EmployeeDTO getEmployeeById(Integer employeeId) {
        System.out.println("Method getEmployeeById() called");
        return new EmployeeDTO();
    }
    public List<EmployeeDTO> getAllEmployee() {
        System.out.println("Method getAllEmployee() called");
        return new ArrayList<EmployeeDTO>();
    }
    public void createEmployee(EmployeeDTO employee) {
        System.out.println("Method createEmployee() called");
    }
    public void deleteEmployee(Integer employeeId) {
        System.out.println("Method deleteEmployee() called");
    }
    public void updateEmployee(EmployeeDTO employee) {
        System.out.println("Method updateEmployee() called");
    }
}

EmployeeCRUDLoggingAspect.java

public class EmployeeCRUDLoggingAspect
{
    public void logBefore(JoinPoint joinPoint) 
    {
        System.out.println("EmployeeCRUDAspect.logBefore() : " + joinPoint.getSignature().getName());
    }
    public void logAfter(JoinPoint joinPoint) 
    {
        System.out.println("EmployeeCRUDAspect.logAfter() : " + joinPoint.getSignature().getName());
    }
}

EmployeeCRUDTransactionAspect.java

public class EmployeeCRUDTransactionAspect
{
    public void getEmployeeById(JoinPoint joinPoint)
    {
        System.out.println("EmployeeCRUDTransactionAspect.getEmployeeById() : "
                + joinPoint.getSignature().getName());
    }
}

TestAOP.java

public class TestAOP
{
    @SuppressWarnings("resource")
    public static void main(String[] args) 
    {
        ApplicationContext context = new ClassPathXmlApplicationContext("com/howtodoinjava/demo/aop/applicationContext.xml");
        EmployeeManager manager = ( EmployeeManager ) context.getBean("employeeManager");
        manager.getEmployeeById(1);
        manager.createEmployee(new EmployeeDTO());
        manager.deleteEmployee(100);
    }
}
Output:
EmployeeCRUDAspect.logBefore() : getEmployeeById
EmployeeCRUDTransactionAspect.getEmployeeById() : getEmployeeById
Method getEmployeeById() called
EmployeeCRUDAspect.logAfter() : getEmployeeById
EmployeeCRUDAspect.logBefore() : createEmployee
Method createEmployee() called
EmployeeCRUDAspect.logAfter() : createEmployee
EmployeeCRUDAspect.logBefore() : deleteEmployee
Method deleteEmployee() called
EmployeeCRUDAspect.logAfter() : deleteEmployee

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