这篇文章旨在记录关于SpringMVC过程中会用到的监听器
1.Servlet监听
用来监听Servlet的生命周期。
主要类：ServletContextListener（监听网站启动过程）,
HttpSessionListener（监听客户端会话过程）, HttpSessionAttributeListener
实现：
创建类实现以上的接口比如：
public class TestListener implements ServletContextListener,
HttpSessionListener, HttpSessionAttributeListener {
.....
｝
web.xml配置：
<listener>
<listener-class>com.test.TestListener</listener-class>
</listener>
2.Bean 初始化监听
可以监听Spring创建Bean的实例的初始化前后
主要类：
BeanPostProcessor
实现：
public class TestProcess implements BeanPostProcessor,Ordered {
public Object postProcessBeforeInitialization(Object o, String s) throws BeansException {
System.out.println("postProcessBeforeInitialization");
return o;
}
public Object postProcessAfterInitialization(Object o, String s) throws BeansException {
System.out.println("postProcessAfterInitialization");
return o;
}
public int getOrder() {
return 1;
}
}
Order主要在于多个同等类时执行的顺序，return返回的是对象，这里可以偷天换日。
SpringContext.xml：
<bean id="testpost" class="....TestProcess"></bean>
3.类的初始化和销毁的监听。
此监听旨在监听bean的自身初始化和销毁过程，初始化的执行方法在第2个监听之后
实现：
第一种1.SpringContext.xml
<bean id="helloWorld" class="com.tutorialspoint.HelloWorld"
init-method="init" destroy-method="destroy">
<property name="message" value="Hello World!"/>
</bean>
通过init-method和destroy-method设置。
第二种2.在bean中
@PostConstruct
public void init(){
System.out.println("Bean is going through init.");
}
@PreDestroy
public void destroy(){
System.out.println("Bean will destroy now.");
}
4.AOP。
面向切面编程
第一种方式：
SpringContext.xml:
<aop:config>
<aop:aspect id="myaspect" ref="peoAsp">
<aop:pointcut id="mypointcut" expression="execution(* jis.*.*(..))"/>
<aop:before method="beforeAdvice" pointcut-ref="mypointcut"/>
<aop:after-throwing method="AfterThrowingAdvice" pointcut-ref="mypointcut" throwing="ex"/>
<aop:after-returning method="afterReturningAdvice" pointcut-ref="mypointcut" returning="retVal"/>
</aop:aspect>
</aop:config>
第二种方式：
Bean中：
@Aspect
public class PeoAsp {
public PeoAsp(){}
@Pointcut("execution(* com.jis.People.aspTest(..))")
public void selectAll(){};
/**
* This is the method which I would like to execute
* before a selected method execution.
*/
@Before("selectAll()")
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.
*/
@After("selectAll()")
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.
*/
@AfterReturning(pointcut = "selectAll()",returning = "retVal")
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(Exception ex){
System.out.println("There has been an exception: " + ex.toString());
}
}
并在SpringContext中配置：
<aop:aspectj-autoproxy/>
<bean class="com.jis.PeoAsp" id="peoAsp"></bean>
