Spring框架中的aop操作之二 通过配置文件实现增强

Posted 2020-10-15 Advancing Swift

aop表达式写法

配置文件代码：

<?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"
    xmlns:aop="http://www.springframework.org/schema/aop"
    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
         http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
    <!-- 开启注解扫描 -->
    <context:component-scan base-package="com.swift"></context:component-scan>
    
    <bean id="book" class="com.swift.aop.Book"></bean>
    <bean id="adviceBook" class="com.swift.aop.AdviceBook"></bean>
    
    <aop:config>
    <!-- 切入点表达式第一个*表示public private等权限后接空格，第二个*表示任意方法(..)表示参数 -->
    <aop:pointcut expression="execution(* com.swift.aop.Book.*())" id="pointcut1"/>
    
    <!-- 哪个切面（用来增强切入点的类） 名称是什么用ref表示 -->
    <aop:aspect ref="adviceBook">
    <!-- 增强的具体方法，增强哪个切入点 -->
    <aop:before method="before" pointcut-ref="pointcut1"/>
    </aop:aspect>
    </aop:config>
</beans>

包括bean context aop三个约束

以及切面的配置——表达式execution含义、advice通知/增强设置

---

 

连接点joinpoint的类，即需要被增强的类：

package com.swift.aop;

public class Book {
    public String fun() {
        System.out.println("This is Book\'s fun()..............");
        return "This is Book\'s fun()..............";
    }
}

进行切面操作的类：

package com.swift.aop;

public class AdviceBook {
    public String before() {
        System.out.println("This is AdviceBook\'s before()...............");
        return "This is AdviceBook\'s before()...............";
    }
}

测试的类：

package com.swift.web;

import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import com.swift.aop.Book;
@WebServlet("/test")
public class ServleTest extends HttpServlet {
    private static final long serialVersionUID = 1L;
    public ServleTest() {
        super();
    }
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        response.getWriter().append("Served at: ").append(request.getContextPath());
        ApplicationContext context=new ClassPathXmlApplicationContext("aop.xml");
        Book book=(Book)context.getBean("book");
        response.getWriter().append(book.fun());
    }
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

演示效果图：

浏览器无反应

只有Book的方法，没有前置的before，想来应该是调用了但是返回的字符串没能显示在浏览器上

控制台console成功

前置增强在切入点前输出

---

 

如果是后置增强，只需要在增强的类中，增加后置增强的方法

public String after() {
System.out.println("This is AdviceBook\'s after()...............");
return "This is AdviceBook\'s after()...............";
}

然后在xml配置文件中添加切面配置的代码

<aop:after-returning method="after" pointcut-ref="pointcut1"/>

即可。

---

 

还有一个环绕的方法，有一个很长的表达不好记 ProceedingJoinPoint这个参数的对象有个方法，执行就是切入点的方法

在增强类中写方法

public String around(ProceedingJoinPoint proceedingJoinPoint) throws Throwable {
System.out.println("This is AdviceBook\'s front()...............");
proceedingJoinPoint.proceed();
System.out.println("This is AdviceBook\'s end()...............");
return "This is AdviceBook\'s around()...............";
}

在<aop:config></aop:config>中写

<aop:around method="around" pointcut-ref="pointcut1"/>

 ===================================================================================================

重新整理上边内容

切入点

package cn.itcast.f_aspect;


public class CRUD {
    public void add() {
        System.out.println("增加内容");
        int i=1/0;
    }
    public void delete() {
        System.out.println("删除内容");
    }
    public void update() {
        System.out.println("修改内容");
    }
    public void find() {
        System.out.println("查找内容");
    }
}

增强

package cn.itcast.f_aspect;

import org.aspectj.lang.ProceedingJoinPoint;

public class Myadvice {

    public void before() {
        System.out.println("之前-->开启事务");
    }
    public void round(ProceedingJoinPoint proceedingJoinPoint) {
        System.out.println("之前-->开启事务");
        try {
            proceedingJoinPoint.proceed();
            System.out.println("没有异常,之后-->提交事务");
        } catch (Throwable e) {
            System.out.println("出现异常,之后--回滚事务");
        }finally {
            System.out.println("有无异常都执行,之后-->关闭事务");
        }
        
    }
    public void afterReturning() {
        System.out.println("没有异常,之后-->提交事务");
    }
    public void after() {
        System.out.println("有无异常都执行,之后-->关闭事务");
    }
    public void afterThrowing() {
        System.out.println("出现异常,之后--回滚事务");
    }
}

通过XML配置

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 xmlns="http://www.springframework.org/schema/beans" 
 xmlns:context="http://www.springframework.org/schema/context" 
 xmlns:aop="http://www.springframework.org/schema/aop"
 xsi:schemaLocation="http://www.springframework.org/schema/beans
                     http://www.springframework.org/schema/beans/spring-beans-4.2.xsd 
                     http://www.springframework.org/schema/context 
                            http://www.springframework.org/schema/context/spring-context-4.2.xsd
                       http://www.springframework.org/schema/aop
                       http://www.springframework.org/schema/aop/spring-aop-4.2.xsd ">
    <!-- 开启ioc注解 -->
    <context:component-scan base-package="cn.itcast"></context:component-scan>
    
    <!---->
    <bean name="car1" class="cn.itcast.domain.Car">
        <property name="name" value="五菱宏光"></property>
    </bean>
    <bean name="car2" class="cn.itcast.domain.Car">
        <property name="name" value="长安CS95"></property>
    </bean>
    <bean name="crud" class="cn.itcast.f_aspect.CRUD"></bean>
    <bean name="myadvice" class="cn.itcast.f_aspect.Myadvice"></bean>
    
    <aop:config>
        <!-- 切入点 -->
        <aop:pointcut expression="execution(public void cn.itcast.f_aspect.CRUD.*())" id="pointcut1"/>
        <!-- 切面两部分:增强和切入点 -->
        <aop:aspect ref="myadvice">
            <aop:before method="before" pointcut-ref="pointcut1"/>
            <aop:around method="round" pointcut-ref="pointcut1"/>
            <aop:after-returning method="afterReturning" pointcut-ref="pointcut1"/>
            <aop:after method="after" pointcut-ref="pointcut1"/>
            <aop:after-throwing method="afterThrowing" pointcut-ref="pointcut1"/>
        </aop:aspect>
    </aop:config>
    
</beans>

测试类

package cn.itcast.f_aspect;

import org.junit.Test;
import org.junit.runner.RunWith;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.test.context.ContextConfiguration;
import org.springframework.test.context.junit4.SpringJUnit4ClassRunner;

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration("classpath:applicationContext.xml")
public class DemoCRUD {

    @Autowired
    private CRUD crud;
    @Test
    public void execute() {
        crud.add();
    }
}

结果