/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.openejb.core.cmp.cmp2;
import org.apache.xbean.asm5.ClassWriter;
import org.apache.xbean.asm5.MethodVisitor;
import org.apache.xbean.asm5.Opcodes;
import org.apache.xbean.asm5.Type;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
/**
* Generate concrete implementations of EjbPostCreatexxx
* methods for a bean class. This is implemented in a separate
* class because it is used by both the CMP1 and CMP2 generators.
*
* @version $Rev: 1607852 $ $Date: 2014-07-04 15:32:03 +0200 (Fri, 04 Jul 2014) $
*/
public class PostCreateGenerator {
private final Class beanClass;
private final ClassWriter cw;
/**
* Constructor for a PostCreateGenerator.
*
* @param beanClass The source EJB implementation class (the user
* provided class).
* @param cw The ClassWriter instance used for constructing the
* instantiation class. This has already gone through
* other generation steps, we're implementing additional
* stages of the process.
*/
public PostCreateGenerator(final Class beanClass, final ClassWriter cw) {
this.beanClass = beanClass;
this.cw = cw;
}
/**
* Generate the ejbPostCreatexxxx methods. Inorder to
* be considered for generation, there must A) be a
* corresponding ejbCreatexxxx method and B) the
* target method must either not exist or exist but be
* abstract.
*/
public void generate() {
// ok, scan the class for the ejbCreate methods and check to see if
// we need to provide an ejbPostCreate implementation.
for (final Method ejbCreate : beanClass.getMethods()) {
if (!ejbCreate.getName().startsWith("ejbCreate")) {
continue;
}
final StringBuilder ejbPostCreateName = new StringBuilder(ejbCreate.getName());
ejbPostCreateName.replace(0, "ejbC".length(), "ejbPostC");
// if there is a concrete method here, we just skip this.
if (hasMethod(beanClass, ejbPostCreateName.toString(), ejbCreate.getParameterTypes())) {
continue;
}
// we need to generate this method
createEjbPostCreate(ejbPostCreateName.toString(), ejbCreate);
}
}
/**
* Test whether a class provides a concrete implementation
* of a class with the given name and parameter types.
*
* @param beanClass The source implementation class.
* @param name The required method name.
* @param args The list of argument types.
* @return true if the method exists and is NOT abstract. Returns
* false if the method is not found or IS abstract.
*/
private boolean hasMethod(final Class beanClass, final String name, final Class... args) {
try {
final Method method = beanClass.getMethod(name, args);
return !Modifier.isAbstract(method.getModifiers());
} catch (final NoSuchMethodException e) {
return false;
}
}
/**
* Generate an ejbPostCreatexxxx method corresponding
* to an ejbCreatexxxx method definition. These provided
* methods are just empty stubs.
*
* @param ejbPostCreateName The name we're creating under.
* @param ejbCreate The matching ejbCreate method. The post create method
* will match this one in terms of method signature.
*/
public void createEjbPostCreate(final String ejbPostCreateName, final Method ejbCreate) {
final String methodDescriptor = Type.getMethodDescriptor(Type.VOID_TYPE, Type.getArgumentTypes(ejbCreate));
final MethodVisitor mv = cw.visitMethod(Opcodes.ACC_PUBLIC, ejbPostCreateName, methodDescriptor, null, null);
mv.visitCode();
mv.visitInsn(Opcodes.RETURN);
mv.visitMaxs(0, ejbCreate.getParameterTypes().length + 1);
mv.visitEnd();
}
}