Java tutorial
/* * 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.tuscany.sca.interfacedef.java.jaxrs; import java.lang.reflect.Array; import java.lang.reflect.GenericArrayType; import java.lang.reflect.ParameterizedType; import java.lang.reflect.Type; import java.lang.reflect.TypeVariable; import java.lang.reflect.WildcardType; import java.util.ArrayList; import java.util.Collection; import java.util.HashMap; import java.util.List; import java.util.Map; import org.objectweb.asm.Opcodes; /** * @version $Rev: 951651 $ $Date: 2010-06-05 06:17:47 +0100 (Sat, 05 Jun 2010) $ */ public class CodeGenerationHelper { /** * @param type * @return */ public static Class<?> getErasure(Type type) { if (type instanceof Class) { return (Class<?>) type; } else if (type instanceof GenericArrayType) { GenericArrayType arrayType = (GenericArrayType) type; Class<?> componentType = getErasure(arrayType.getGenericComponentType()); return Array.newInstance(componentType, 0).getClass(); } else if (type instanceof ParameterizedType) { ParameterizedType pType = (ParameterizedType) type; return getErasure(pType.getRawType()); } else if (type instanceof WildcardType) { WildcardType wType = (WildcardType) type; Type[] types = wType.getUpperBounds(); if (types.length == 0) { return Object.class; } return getErasure(types[0]); } else if (type instanceof TypeVariable) { TypeVariable<?> var = (TypeVariable<?>) type; Type[] types = var.getBounds(); if (types.length == 0) { return Object.class; } return getErasure(types[0]); } return null; } /** * @param type * @return */ public static String getJAXWSSignature(Type type) { Class<?> cls = getErasure(type); if (Collection.class.isAssignableFrom(cls) && (type instanceof ParameterizedType)) { ParameterizedType pType = (ParameterizedType) type; Type p = pType.getActualTypeArguments()[0]; StringBuffer sb = new StringBuffer(); sb.append(getSignature(cls)); sb.deleteCharAt(sb.length() - 1); // Remove ; sb.append('<').append(getSignature(getErasure(p))).append(">;"); return sb.toString(); } else if (Map.class.isAssignableFrom(cls) && (type instanceof ParameterizedType)) { ParameterizedType pType = (ParameterizedType) type; Type key = pType.getActualTypeArguments()[0]; Type value = pType.getActualTypeArguments()[1]; StringBuffer sb = new StringBuffer(); sb.append(getSignature(cls)); sb.deleteCharAt(sb.length() - 1); // Remove ; sb.append('<').append(getSignature(getErasure(key))).append(getSignature(getErasure(value))) .append(">;"); return sb.toString(); } else { return getSignature(cls); } } /** * @param type * @return */ public static String getSignature(Type type) { if (!(type instanceof Class)) { if (type instanceof ParameterizedType) { ParameterizedType pType = (ParameterizedType) type; StringBuffer sb = new StringBuffer(); String rawType = getSignature(pType.getRawType()); sb.append(rawType.substring(0, rawType.length() - 1)); sb.append('<'); for (Type t : pType.getActualTypeArguments()) { String argType = getSignature(t); sb.append(argType); } sb.append('>'); sb.append(rawType.substring(rawType.length() - 1)); return sb.toString(); } if (type instanceof TypeVariable) { return "T" + ((TypeVariable<?>) type).getName() + ";"; } if (type instanceof GenericArrayType) { GenericArrayType arrayType = (GenericArrayType) type; return "[" + getSignature(arrayType.getGenericComponentType()); } if (type instanceof WildcardType) { WildcardType wType = (WildcardType) type; Type[] types = wType.getUpperBounds(); StringBuffer sb = new StringBuffer(); if (types.length == 0 || !(types.length == 1 && types[0] == Object.class)) { sb.append('+'); for (Type t : types) { sb.append(getSignature(t)); } } types = wType.getLowerBounds(); if (types.length != 0) { sb.append('-'); for (Type t : wType.getLowerBounds()) { sb.append(getSignature(t)); } } if (sb.length() == 0) { return "*"; } return sb.toString(); } } Class<?> cls = (Class<?>) type; return org.objectweb.asm.Type.getDescriptor(cls); } /** * Get the actual type arguments a child class has used to extend a generic base class. * * @param baseClass the base class * @param childClass the child class * @return a list of the raw classes for the actual type arguments. */ public static <T> List<Class<?>> resovleTypeArguments(Class<T> baseClass, Class<? extends T> childClass) { Map<Type, Type> resolvedTypes = new HashMap<Type, Type>(); Type type = childClass; // start walking up the inheritance hierarchy until we hit baseClass while (!getErasure(type).equals(baseClass)) { if (type instanceof Class) { // there is no useful information for us in raw types, so just keep going. type = ((Class<?>) type).getGenericSuperclass(); } else { ParameterizedType parameterizedType = (ParameterizedType) type; Class<?> rawType = getErasure(parameterizedType.getRawType()); Type[] actualTypeArguments = parameterizedType.getActualTypeArguments(); TypeVariable<?>[] typeParameters = rawType.getTypeParameters(); for (int i = 0; i < actualTypeArguments.length; i++) { resolvedTypes.put(typeParameters[i], actualTypeArguments[i]); } if (!rawType.equals(baseClass)) { type = rawType.getGenericSuperclass(); } } } // finally, for each actual type argument provided to baseClass, determine (if possible) // the raw class for that type argument. Type[] actualTypeArguments; if (type instanceof Class) { actualTypeArguments = ((Class<?>) type).getTypeParameters(); } else { actualTypeArguments = ((ParameterizedType) type).getActualTypeArguments(); } List<Class<?>> typeArgumentsAsClasses = new ArrayList<Class<?>>(); // resolve types by chasing down type variables. for (Type baseType : actualTypeArguments) { while (resolvedTypes.containsKey(baseType)) { baseType = resolvedTypes.get(baseType); } typeArgumentsAsClasses.add(getErasure(baseType)); } return typeArgumentsAsClasses; } /* signatures.put(boolean.class, "Z"); signatures.put(byte.class, "B"); signatures.put(char.class, "C"); signatures.put(short.class, "S"); signatures.put(int.class, "I"); signatures.put(long.class, "J"); signatures.put(float.class, "F"); signatures.put(double.class, "D"); */ public static int getLoadOPCode(String signature) { if ("Z".equals(signature) || "B".equals(signature) || "C".equals(signature) || "S".equals(signature) || "I".equals(signature)) { return Opcodes.ILOAD; } if ("J".equals(signature)) { return Opcodes.LLOAD; } if ("F".equals(signature)) { return Opcodes.FLOAD; } if ("D".equals(signature)) { return Opcodes.DLOAD; } return Opcodes.ALOAD; } public static int getReturnOPCode(String signature) { if ("Z".equals(signature) || "B".equals(signature) || "C".equals(signature) || "S".equals(signature) || "I".equals(signature)) { return Opcodes.IRETURN; } if ("J".equals(signature)) { return Opcodes.LRETURN; } if ("F".equals(signature)) { return Opcodes.FRETURN; } if ("D".equals(signature)) { return Opcodes.DRETURN; } if ("V".equals(signature)) { return Opcodes.RETURN; } return Opcodes.ARETURN; } /** * Get the package prefix for generated JAXWS artifacts * @param cls * @return */ public static String getPackagePrefix(Class<?> cls) { String name = cls.getName(); int index = name.lastIndexOf('.'); if (index == -1) { return "jaxws."; } else { return name.substring(0, index) + ".jaxws."; } } }