MethodInterceptor 的几种用法（二）
前言
发现写着写着好像越来越偏离正轨了，果然还是知道得太少了；这篇算是MethodInterceptor的第二篇了吧，本来没想写这篇文章的，但是看了看源码，颠覆我之前已有的认知，感觉还是得把这篇文章写出来；
正文
上一篇MethodInterceptor的文章都是以配置注解的形式来将MethodInterceptor注册生效，这次这篇将使用spring原生的类或接口来将MethodInterceptor注册并生效。
TestInterceptorAnnotation
先自定义注解TestInterceptorAnnotation 注解
@Target(ElementType.METHOD)
@Retention(RetentionPolicy.RUNTIME)
@Documented
public @interface TestInterceptorAnnotation {
}
TestInterceptor
写一个MethodInterceptor的实现类TestInterceptor：
public class TestInterceptor implements MethodInterceptor, Ordered {
@Override
public Object invoke(MethodInvocation methodInvocation) throws Throwable {
System.out.println("开始执行");
Object result = methodInvocation.proceed();
System.out.println("结束执行");
return result;
}
@Override
public int getOrder() {
return Ordered.HIGHEST_PRECEDENCE;
}
}
AnnotationAdvisor
写一个AnnotationAdvisor类，去继承AbstractPointcutAdvisor类，代码如下：
public class AnnotationAdvisor extends AbstractPointcutAdvisor {
private Advice advice;
private Pointcut pointcut;
public AnnotationAdvisor() {
this.advice = new TestInterceptor();
}
@Override
public boolean isPerInstance() {
return false;
}
@Override
public Pointcut getPointcut() {
return this.pointcut;
}
@Override
public Advice getAdvice() {
return this.advice;
}
public void setMyPointcut() {
this.pointcut = new AnnotationMatchingPointcut(null,TestInterceptorAnnotation.class);
}
public void setMyPointcutA() {
AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();
pointcut.setExpression("execution(* com.example.threaddemo..*.*(..))");
this.pointcut = pointcut;
}
public void setMyPointcutB() {
AspectJExpressionPointcut pointcut = new AspectJExpressionPointcut();
pointcut.setExpression("@annotation(com.example.threaddemo.annotation.TestInterceptorAnnotation)");
this.pointcut = pointcut;
}
public void setMyPointcutC() {
JdkRegexpMethodPointcut pointcut = new JdkRegexpMethodPointcut();
pointcut.setPattern("com.example.threaddemo.*");
this.pointcut = pointcut;
}
// 以下的两个方法是参考的EnableAsync源码中的一部分代码
public void setAsyncAnnotationType(Class<? extends Annotation> asyncAnnotationType) {
Assert.notNull(asyncAnnotationType, "'asyncAnnotationType' must not be null");
Set<Class<? extends Annotation>> asyncAnnotationTypes = new HashSet<Class<? extends Annotation>>();
asyncAnnotationTypes.add(asyncAnnotationType);
this.pointcut = buildPointcut(asyncAnnotationTypes);
}
protected Pointcut buildPointcut(Set<Class<? extends Annotation>> asyncAnnotationTypes) {
ComposablePointcut result = null;
for (Class<? extends Annotation> asyncAnnotationType : asyncAnnotationTypes) {
Pointcut cpc = new AnnotationMatchingPointcut(asyncAnnotationType, true);
Pointcut mpc = AnnotationMatchingPointcut.forMethodAnnotation(asyncAnnotationType);
if (result == null) {
result = new ComposablePointcut(cpc).union(mpc);
} else {
result.union(cpc).union(mpc);
}
}
return result;
}
}
这个代码比较多，基本上把上一篇的代码都带过来了，这里主要是注意构造切点的几个方法;
AnnotationBeanPostProcessor
最关键的来了，新建类AnnotationBeanPostProcessor，继承AbstractBeanFactoryAwareAdvisingPostProcessor：
//这里注意将该类注册进spring容器
@Component
public class AnnotationBeanPostProcessor extends AbstractBeanFactoryAwareAdvisingPostProcessor {
@Override
public void setBeanFactory(BeanFactory beanFactory) {
super.setBeanFactory(beanFactory);
AnnotationAdvisor advisor = new AnnotationAdvisor();
//这里就看自己选择哪一种切面方式了
advisor.setAsyncAnnotationType(TestInterceptorAnnotation.class);
this.advisor = advisor;
}
}
总结
这篇文章主要参考的EnableAsync源码的AsyncAnnotationBeanPostProcessor类
