|
AOP
Aspect-Oriented Programming for GWT
1, IntroductionNow Aspect-Oriented Programming is available in GWT. The following advice type supported by GWTENT(Compatible with AspectJ annotation).
And for pointcut, we support both Google Guice matcher classes and AspectJ expression(a subset of AspectJ expression) Please see here for all interceptors in sample project. Please download the sample projecthere 2, Pointcut2.1, OverviewPointcut: A predicate that matches join points. Advice is associated with a pointcut expression and runs at any join point matched by the pointcut (for example, the execution of a method with a certain name). The concept of join points as matched by pointcut expressions is central to AOP: we support AspectJ pointcut language and Google Guice matcher classes. 2.1.1, Client-side code?Please note, All pointcut match code is runing at compile time, it's mean you can write truely java code in your matcher class and without any limit in GWT client-side code. In compile time and host-mode, GWTENT require AspectJ jars to dealwith AspectJ expression, but after your compile it, all are javascript. 2.2, AspectJ pointcut expression styleto be continue 2.2, Google Guice matcher styleWe support "matchclass(the class name which implement com.gwtent.aop.matcher.ClassMethodMatcher)", for example:
the matcher class will looks like this: public class TestMatcher implements ClassMethodMatcher {
public Matcher<? super Class<?>> getClassMatcher() {
return Matchers.subclassesOf(Phone.class);
}
public Matcher<? super Method> getMethodMatcher() {
return Matchers.returns(Matchers.only(Phone.Receiver.class));
//return Matchers.any();
}
}3, Advice3.1, Arguments Binding
@AfterReturning( pointcut="**", returning="retVal" ) public void afterReturning(Object retVal) @AfterThrowing( throwing="e" } public void afterThrowing(Throwable e) 3.2, @AroundAdvice that surrounds a join point such as a method invocation. This is the most powerful kind of advice. Around advice can perform custom behavior before and after the method invocation. It is also responsible for choosing whether to proceed to the join point or to shortcut the advised method execution by returning its own return value or throwing an exception. 3.2.1, Example @Around("execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))")
public Object invoke(MethodInvocation invocation) throws Throwable {
invocation.proceed();
System.out.println("Do something in PhoneRedirectInterceptor...");
return new Receiver("Alberto's Pizza Place");
}3.3, @BeforeAdvice that executes before a join point, but which does not have the ability to prevent execution flow proceeding to the join point (unless it throws an exception). 3.3.1, Example @Before("execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))")
public void beforeCall(MethodInvocation invocation) {
for (Object arg : invocation.getArguments()){
System.out.println("Do something in PhoneLoggerInterceptor, Before...");
if (arg instanceof Number)
System.out.println("Call to: " + arg);
}
}3.4, @AfterAfter (finally) Advice to be executed regardless of the means by which a join point exits (normal or exceptional return). 3.4.1, Example @After("execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))")
public void afterCall(MethodInvocation invocation) {
for (Object arg : invocation.getArguments()){
System.out.println("Do something in PhoneLoggerInterceptor, After...");
if (arg instanceof Number)
System.out.println("After Call: " + arg);
}
}3.5, @AfterReturningAdvice to be executed after a join point completes normally: for example, if a method returns without throwing an exception. 3.5.1, Example @AfterReturning(pointcut = "execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))",
returning = "returnValue")
public void afterReturningCall(MethodInvocation invocation, Object returnValue) {
System.out.println("Do something in PhoneLoggerInterceptor, AfterReturning...");
if ((returnValue != null)){
if (returnValue instanceof Number)
System.out.println("Returning Number: " + returnValue.toString());
else
System.out.println("Returning Object: " + returnValue.toString());
}else{
System.out.println("Returning Object is NULL?");
}
}3.6, @AfterThrowingAdvice to be executed if a method exits by throwing an exception. 3.6.1, Example @AfterThrowing(pointcut="execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))",
throwing="e")
public void phoneCallErrorLog(MethodInvocation invocation, Throwable e){
System.out.println("PhoneCallErrorLog: " + e.getMessage());
}4, The whole exampleClassThe normal gwt class, for now you need implement "Aspectable" mark interface
public class Phone implements Aspectable {
private static final Map<Number, Receiver> RECEIVERS = new HashMap<Number, Receiver>();
static {
RECEIVERS.put(123456789, new Receiver("Aunt Jane"));
RECEIVERS.put(111111111, new Receiver("Santa"));
}
/**
* the phone number, like your home number
*/
private Number number;
public Receiver call(Number number) {
System.out.println("The call here...");
Receiver result = RECEIVERS.get(number);
if (result != null)
return result;
else
throw new NumberNotFoundException("Can't found receiver, number: " + number);
}
public Receiver call(String number){
System.out.println("The call here...");
return RECEIVERS.get(111111111);
}
public String toString(){
return super.toString();
}
public void setNumber(Number number) {
this.number = number;
}
public Number getNumber() {
return number;
}
public static class NumberNotFoundException extends RuntimeException{
/**
*
*/
private static final long serialVersionUID = 1L;
public NumberNotFoundException(String msg){
super(msg);
}
}
public static class Receiver {
private final String name;
public Receiver(String name) {
this.name = name;
}
@Override
public String toString() {
return getClass().getName() + "[name=" + name + "]";
}
}Aspect Classes
@Aspect
public static class PhoneLoggerInterceptor {
//execution(modifiers-pattern? ret-type-pattern declaring-type-pattern? name-pattern(param-pattern) throws-pattern?)
@Before("execution(* com.gwtent.client.test.aop.Phone.call(java.lang.Number))")
public void beforeCall(MethodInvocation invocation) {
for (Object arg : invocation.getArguments()){
System.out.println("Do something in PhoneLoggerInterceptor, Before...");
if (arg instanceof Number)
System.out.println("Call to: " + arg);
}
}
@AfterReturning(pointcut = "execution(* com.gwtent.client.test.aop.Phone.call(java.lang.Number))",
returning = "returnValue")
public void afterReturningCall(MethodInvocation invocation, Object returnValue) {
System.out.println("Do something in PhoneLoggerInterceptor, AfterReturning...");
if ((returnValue != null)){
if (returnValue instanceof Number)
System.out.println("Returning Number: " + returnValue.toString());
else
System.out.println("Returning Object: " + returnValue.toString());
}else{
System.out.println("Returning Object is NULL?");
}
}
@After("execution(* com.gwtent.sample.client.Phone.call(java.lang.Number))")
public void afterCall(MethodInvocation invocation) {
for (Object arg : invocation.getArguments()){
System.out.println("Do something in PhoneLoggerInterceptor, After...");
if (arg instanceof Number)
System.out.println("After Call: " + arg);
}
}
}
@Aspect
public static class PhoneRedirectInterceptor {
@Around("execution(* com.gwtent.client.test.aop.Phone.call(java.lang.Number))")
public Object invoke(MethodInvocation invocation) throws Throwable {
invocation.proceed();
System.out.println("Do something in PhoneRedirectInterceptor...");
return new Receiver("Alberto's Pizza Place");
}
}Using it public void testAOP(){
Phone phone = (Phone) GWT.create(Phone.class);
Receiver auntJane = phone.call(123456789);
System.out.println(auntJane);
}The Result - System OutputDo something in PhoneLoggerInterceptor, Before... Call to: 123456789 Validate, you cann't dail to 0, current Number(most time it's null): null The call here... Do something in PhoneRedirectInterceptor... Do something in PhoneLoggerInterceptor, After... After Call: 123456789 Do something in PhoneLoggerInterceptor, AfterReturning... Returning Object: com.gwtent.sample.client.Phone$Receiver[name=Alberto's Pizza Place] com.gwtent.sample.client.Phone$Receiver[name=Alberto's Pizza Place] |
Sign in to add a comment
Hi excellent tutorial thanks.
I noticed that
@After("execution( com.gwtent.sample.client.Phone.call(java.lang.Number))") public void afterCall(MethodInvocation? invocation) {
is only called the first time call() is executed. Is there anyway for afterCall() to be executed every time call() is executed?
Thanks
The showcase download is corrupted.
Can you please include a how to install. I've added: "<inherits name="com.gwtent.GwtEntAll"/>" to the xml, thrown in all the jars I could come up with, "implements Aspectable", etc. The code compiles but the interceptors aren't being executed.
I don't know if I'm missing, jars, configs, etc.
Btw, what jars do I need if I'm only using gwt-ent for aspects? I don't have spring, etc. installed as part of this system.