Hi, Guys,
Aspect-Oriented Programming for GWT, GWTENT-0.5 now available for
download.
Please see here or read through this post for more information:
http://code.google.com/p/gwt-ent/wiki/AOP
You can get all interceptors in sample project at
http://gwt-ent.googlecode.com/svn/trunk/gwtent-sample/src/com/gwtent/sample/client/Interceptors.java
Please download the sample project at
http://code.google.com/p/gwt-ent/downloads/list
If you get anything, any advises, issues, please let me know, let us
make it better. :D
1, Introduction
Now Aspect-Oriented Programming is available in GWT.
The following advice type supported by GWTENT(Compatible with
AspectJ annotation).
1. @Around
2. @Before
3. @After
4. @AfterReturning?
5. @AfterThrowing?
* Around advice: Advice 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.
* Before advice: Advice 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).
* After (finally) advice: Advice to be executed regardless of the
means by which a join point exits (normal or exceptional return).
* After returning advice: Advice to be executed after a join point
completes normally: for example, if a method returns without throwing
an exception.
* After throwing advice: Advice to be executed if a method exits
by throwing an exception.
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, Pointcut
2.1, Overview
Pointcut: 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 style
to be continue
2.2, Google Guice matcher style
We support "matchclass(the class name which implement
com.gwtent.aop.matcher.ClassMethodMatcher?)", for example:
@Aspect
public static class PhoneRedirectInterceptor {
@Around("matchclass
(com.gwtent.test.aspectj.TestMatcher)")
public Object invoke(MethodInvocation invocation)
throws Throwable {
invocation.proceed();
System.out.println("Do something in
PhoneRedirectInterceptor...");
return new Receiver("Alberto's Pizza
Place");
}
}
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, Advice
3.1, Arguments Binding
1. if there is "com.gwtent.client.aop.intercept.MethodInvocation?"
in args list, then invocation will assign to args.
2. if source method and advice method have the same class type and
this type just have one, then we assign this one to args
3. Read settings in @AfterReturning?
@AfterReturning(
pointcut="**",
returning="retVal"
)
public void afterReturning(Object retVal)
4. Read settings in @AfterThrowing?
@AfterThrowing(
throwing="e"
}
public void afterThrowing(Throwable e)
3.2, @Around
Advice 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, @Before
Advice 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, @After
After (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, @AfterReturning?
Advice 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, @AfterThrowing?
Advice 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 example
Class
The 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 Output
Do 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]
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