Spring框架中的aop操作之二 通过配置文件实现增强
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"/>
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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