private Bytecode createAbstractMethodCode(ClassFile file, MethodInformation method)
throws NotFoundException {
if ((delegateField != null) && (!Modifier.isPrivate(delegateField.getModifiers()))) {
// Call the corresponding method directly on the delegate
Bytecode b = new Bytecode(file.getConstPool());
int localVariables = MethodUtils.calculateMaxLocals(method.getMethod());
b.setMaxLocals(localVariables);
// load the delegate field
b.addAload(0);
b.addGetfield(
file.getName(),
delegateField.getName(),
DescriptorUtils.classToStringRepresentation(delegateField.getType()));
// load the parameters
BytecodeUtils.loadParameters(b, method.getDescriptor());
// invoke the delegate method
b.addInvokeinterface(
delegateField.getType().getName(),
method.getName(),
method.getDescriptor(),
localVariables);
// return the value if applicable
BytecodeUtils.addReturnInstruction(b, method.getReturnType());
return b;
} else {
if (!Modifier.isPrivate(method.getMethod().getModifiers())) {
// if it is a parameter injection point we need to initalize the
// injection point then handle the method with the method handler
return createAbstractMethodHandler(file, method);
} else {
// if the delegate is private we need to use the method handler
return createInterceptorBody(file, method);
}
}
}
/**
* calls _initMH on the method handler and then stores the result in the methodHandler field as
* then new methodHandler
*/
private Bytecode createMethodHandlerInitializerBody(ClassFile proxyClassType) {
Bytecode b = new Bytecode(proxyClassType.getConstPool(), 1, 2);
b.add(Opcode.ALOAD_0);
StaticMethodInformation methodInfo =
new StaticMethodInformation(
"_initMH", new Class[] {Object.class}, void.class, proxyClassType.getName());
invokeMethodHandler(proxyClassType, b, methodInfo, false, DEFAULT_METHOD_RESOLVER);
b.addCheckcast("javassist/util/proxy/MethodHandler");
b.addPutfield(
proxyClassType.getName(),
"methodHandler",
DescriptorUtils.classToStringRepresentation(MethodHandler.class));
b.add(Opcode.RETURN);
log.trace("Created MH initializer body for decorator proxy: " + getBeanType());
return b;
}
/**
* When creates the delegate initializer code when the delegate is injected into a method.
*
* <p>super initializer method is called first, and then _initMH is called
*
* @param file
* @param intializerMethodInfo
* @param delegateParameterPosition
* @return
*/
private Bytecode createDelegateInitializerCode(
ClassFile file, MethodInformation intializerMethodInfo, int delegateParameterPosition) {
Bytecode b = new Bytecode(file.getConstPool());
// we need to push all the pareters on the stack to call the corresponding
// superclass arguments
b.addAload(0); // load this
int localVariables = 1;
int actualDelegateParamterPosition = 0;
for (int i = 0; i < intializerMethodInfo.getMethod().getParameterTypes().length; ++i) {
if (i == delegateParameterPosition) {
// figure out the actual position of the delegate in the local
// variables
actualDelegateParamterPosition = localVariables;
}
Class<?> type = intializerMethodInfo.getMethod().getParameterTypes()[i];
BytecodeUtils.addLoadInstruction(
b, DescriptorUtils.classToStringRepresentation(type), localVariables);
if (type == long.class || type == double.class) {
localVariables = localVariables + 2;
} else {
localVariables++;
}
}
b.addInvokespecial(
file.getSuperclass(), intializerMethodInfo.getName(), intializerMethodInfo.getDescriptor());
// if this method returns a value it is now sitting on top of the stack
// we will leave it there are return it later
// now we need to call _initMH
b.addAload(0); // load this
b.addAload(actualDelegateParamterPosition); // load the delegate
b.addInvokevirtual(file.getName(), "_initMH", "(Ljava/lang/Object;)V");
// return the object from the top of the stack that we got from calling
// the superclass method earlier
BytecodeUtils.addReturnInstruction(b, intializerMethodInfo.getReturnType());
b.setMaxLocals(localVariables);
return b;
}
/**
* Calls methodHandler.invoke with a null method parameter in order to get the underlying
* instance. The invocation is then forwarded to this instance with generated bytecode.
*/
protected Bytecode createForwardingMethodBody(ClassFile file, MethodInformation methodInfo)
throws NotFoundException {
Method method = methodInfo.getMethod();
// we can only use bytecode based invocation for some methods
// at the moment we restrict it solely to public methods with public
// return and parameter types
boolean bytecodeInvocationAllowed =
Modifier.isPublic(method.getModifiers())
&& Modifier.isPublic(method.getReturnType().getModifiers());
for (Class<?> paramType : method.getParameterTypes()) {
if (!Modifier.isPublic(paramType.getModifiers())) {
bytecodeInvocationAllowed = false;
break;
}
}
if (!bytecodeInvocationAllowed) {
return createInterceptorBody(file, methodInfo);
}
Bytecode b = new Bytecode(file.getConstPool());
int localCount = MethodUtils.calculateMaxLocals(method) + 1;
// create a new interceptor invocation context whenever we invoke a method on a client proxy
// we use a try-catch block in order to make sure that endInterceptorContext() is invoked
// regardless whether
// the method has succeeded or not
int start = b.currentPc();
b.addInvokestatic(
"org.jboss.weld.bean.proxy.InterceptionDecorationContext",
"startInterceptorContext",
"()V");
b.add(Opcode.ALOAD_0);
b.addGetfield(
file.getName(),
"methodHandler",
DescriptorUtils.classToStringRepresentation(MethodHandler.class));
// pass null arguments to methodHandler.invoke
b.add(Opcode.ALOAD_0);
b.add(Opcode.ACONST_NULL);
b.add(Opcode.ACONST_NULL);
b.add(Opcode.ACONST_NULL);
// now we have all our arguments on the stack
// lets invoke the method
b.addInvokeinterface(
MethodHandler.class.getName(),
"invoke",
"(Ljava/lang/Object;Ljava/lang/reflect/Method;Ljava/lang/reflect/Method;[Ljava/lang/Object;)Ljava/lang/Object;",
5);
b.addCheckcast(methodInfo.getDeclaringClass());
// now we should have the target bean instance on top of the stack
// we need to dup it so we still have it to compare to the return value
b.add(Opcode.DUP);
// lets create the method invocation
String methodDescriptor = methodInfo.getDescriptor();
BytecodeUtils.loadParameters(b, methodDescriptor);
if (method.getDeclaringClass().isInterface()) {
b.addInvokeinterface(
methodInfo.getDeclaringClass(),
methodInfo.getName(),
methodDescriptor,
method.getParameterTypes().length + 1);
} else {
b.addInvokevirtual(methodInfo.getDeclaringClass(), methodInfo.getName(), methodDescriptor);
}
// end the interceptor context, everything was fine
b.addInvokestatic(
"org.jboss.weld.bean.proxy.InterceptionDecorationContext", "endInterceptorContext", "()V");
// jump over the catch block
b.addOpcode(Opcode.GOTO);
JumpMarker gotoEnd = JumpUtils.addJumpInstruction(b);
// create catch block
b.addExceptionHandler(start, b.currentPc(), b.currentPc(), 0);
b.addInvokestatic(
"org.jboss.weld.bean.proxy.InterceptionDecorationContext", "endInterceptorContext", "()V");
b.add(Opcode.ATHROW);
// update the correct address to jump over the catch block
gotoEnd.mark();
// if this method returns a primitive we just return
if (method.getReturnType().isPrimitive()) {
BytecodeUtils.addReturnInstruction(b, methodInfo.getReturnType());
} else {
// otherwise we have to check that the proxy is not returning 'this;
// now we need to check if the proxy has return 'this' and if so return
// an
// instance of the proxy.
// currently we have result, beanInstance on the stack.
b.add(Opcode.DUP_X1);
// now we have result, beanInstance, result
// we need to compare result and beanInstance
// first we need to build up the inner conditional that just returns
// the
// result
b.add(Opcode.IF_ACMPEQ);
JumpMarker returnInstruction = JumpUtils.addJumpInstruction(b);
BytecodeUtils.addReturnInstruction(b, methodInfo.getReturnType());
returnInstruction.mark();
// now add the case where the proxy returns 'this';
b.add(Opcode.ALOAD_0);
b.addCheckcast(methodInfo.getMethod().getReturnType().getName());
BytecodeUtils.addReturnInstruction(b, methodInfo.getReturnType());
}
if (b.getMaxLocals() < localCount) {
b.setMaxLocals(localCount);
}
return b;
}