假设您要使用批注记录某些带批注的方法所花费的时间。@LogExecTime
我首先创建一个注释：LogExecTime
@Retention(RetentionPolicy.RUNTIME)
@Target(ElementType.METHOD)
public @interface LogExecTime {
}
然后我定义一个方面：
@Component // For Spring AOP
@Aspect
public class LogTimeAspect {
@Around(value = "@annotation(annotation)")
public Object LogExecutionTime(final ProceedingJoinPoint joinPoint, final LogExecTime annotation) throws Throwable {
final long startMillis = System.currentTimeMillis();
try {
System.out.println("Starting timed operation");
final Object retVal = joinPoint.proceed();
return retVal;
} finally {
final long duration = System.currentTimeMillis() - startMillis;
System.out.println("Call to " + joinPoint.getSignature() + " took " + duration + " ms");
}
}
}
我创建了一个带有注释的类：LogExecTime
@Component
public class Operator {
@LogExecTime
public void operate() throws InterruptedException {
System.out.println("Performing operation");
Thread.sleep(1000);
}
}
主要使用弹簧AOP：
public class SpringMain {
public static void main(String[] args) throws InterruptedException {
ApplicationContext context = new GenericXmlApplicationContext("applicationContext.xml");
final Operator bean = context.getBean(Operator.class);
bean.operate();
}
}
如果我运行此类，我会在 stdout 上获得以下输出：
Starting timed operation
Performing operation
Call to void testaop.Operator.Operate() took 1044 ms
现在有了魔力。由于我确实使用了Spring AOP而不是AspectJ编织器，因此魔术是在运行时使用代理机制发生的。因此，文件保持不变。例如，如果我调试这个程序并在其中放置一个断点，你会看到Spring是如何执行魔术的：.classoperate
由于Spring AOP实现是非侵入式的，并且使用Spring机制，因此您需要添加注释并使用Spring上下文而不是普通上下文创建对象。@Componentnew
另一边的AspectJ将更改文件。我用AspectJ尝试了这个项目，并用jad反编译了Operator类。这导致：.class
public void operate()
throws InterruptedException
{
JoinPoint joinpoint = Factory.makeJP(ajc$tjp_0, this, this);
operate_aroundBody1$advice(this, joinpoint, LogTimeAspect.aspectOf(), (ProceedingJoinPoint)joinpoint, (LogExecTime)(ajc$anno$0 == null && (ajc$anno$0 = testaop/Operator.getDeclaredMethod("operate", new Class[0]).getAnnotation(testaop/LogExecTime)) == null ? ajc$anno$0 : ajc$anno$0));
}
private static final void operate_aroundBody0(Operator ajc$this, JoinPoint joinpoint)
{
System.out.println("Performing operation");
Thread.sleep(1000L);
}
private static final Object operate_aroundBody1$advice(Operator ajc$this, JoinPoint thisJoinPoint, LogTimeAspect ajc$aspectInstance, ProceedingJoinPoint joinPoint, LogExecTime annotation)
{
long startMillis = System.currentTimeMillis();
Object obj;
System.out.println("Starting timed operation");
ProceedingJoinPoint proceedingjoinpoint = joinPoint;
operate_aroundBody0(ajc$this, proceedingjoinpoint);
Object retVal = null;
obj = retVal;
long duration = System.currentTimeMillis() - startMillis;
System.out.println((new StringBuilder("Call to ")).append(joinPoint.getSignature()).append(" took ").append(duration).append(" ms").toString());
return obj;
Exception exception;
exception;
long duration = System.currentTimeMillis() - startMillis;
System.out.println((new StringBuilder("Call to ")).append(joinPoint.getSignature()).append(" took ").append(duration).append(" ms").toString());
throw exception;
}
private static void ajc$preClinit()
{
Factory factory = new Factory("Operator.java", testaop/Operator);
ajc$tjp_0 = factory.makeSJP("method-execution", factory.makeMethodSig("1", "operate", "testaop.Operator", "", "", "java.lang.InterruptedException", "void"), 5);
}
private static final org.aspectj.lang.JoinPoint.StaticPart ajc$tjp_0; /* synthetic field */
private static Annotation ajc$anno$0; /* synthetic field */
static
{
ajc$preClinit();
}
