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Diffstat (limited to 'sandbox/rfeng/minicore/src/main/java/org/apache/tuscany/core/util/JavaIntrospectionHelper.java')
| -rw-r--r-- | sandbox/rfeng/minicore/src/main/java/org/apache/tuscany/core/util/JavaIntrospectionHelper.java | 439 |
1 files changed, 439 insertions, 0 deletions
diff --git a/sandbox/rfeng/minicore/src/main/java/org/apache/tuscany/core/util/JavaIntrospectionHelper.java b/sandbox/rfeng/minicore/src/main/java/org/apache/tuscany/core/util/JavaIntrospectionHelper.java new file mode 100644 index 0000000000..6b11725481 --- /dev/null +++ b/sandbox/rfeng/minicore/src/main/java/org/apache/tuscany/core/util/JavaIntrospectionHelper.java @@ -0,0 +1,439 @@ +/* + * 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.core.util; + +import java.lang.reflect.Constructor; +import java.lang.reflect.Field; +import java.lang.reflect.Method; +import java.lang.reflect.Modifier; +import java.lang.reflect.ParameterizedType; +import java.lang.reflect.Type; +import java.util.ArrayList; +import java.util.HashSet; +import java.util.List; +import java.util.Set; + +/** + * Implements various reflection-related operations + * + * @version $Rev$ $Date$ + */ +public final class JavaIntrospectionHelper { + + private static final Class[] EMPTY_CLASS_ARRY = new Class[0]; + + /** + * Hide the constructor + */ + private JavaIntrospectionHelper() { + } + + + /** + * Returns a collection of public, and protected fields declared by a class or one of its supertypes + */ + public static Set<Field> getAllPublicAndProtectedFields(Class clazz) { + return getAllPublicAndProtectedFields(clazz, new HashSet<Field>()); + } + + /** + * Recursively evaluates the type hierachy to return all fields that are public or protected + */ + private static Set<Field> getAllPublicAndProtectedFields(Class clazz, Set<Field> fields) { + if (clazz == null || clazz.isArray() || Object.class.equals(clazz)) { + return fields; + } + fields = getAllPublicAndProtectedFields(clazz.getSuperclass(), fields); + Field[] declaredFields = clazz.getDeclaredFields(); + for (Field field : declaredFields) { + int modifiers = field.getModifiers(); + if ((Modifier.isPublic(modifiers) || Modifier.isProtected(modifiers)) && !Modifier.isStatic(modifiers)) { + field.setAccessible(true); // ignore Java accessibility + fields.add(field); + } + } + return fields; + } + + /** + * Returns a collection of public and protected methods declared by a class or one of its supertypes. Note that + * overriden methods will not be returned in the collection (i.e. only the method override will be). <p/> This + * method can potentially be expensive as reflection information is not cached. It is assumed that this method will + * be used during a configuration phase. + */ + public static Set<Method> getAllUniquePublicProtectedMethods(Class clazz) { + return getAllUniqueMethods(clazz, new HashSet<Method>()); + } + + /** + * Recursively evaluates the type hierarchy to return all unique methods + */ + private static Set<Method> getAllUniqueMethods(Class pClass, Set<Method> methods) { + if (pClass == null || pClass.isArray() || Object.class.equals(pClass)) { + return methods; + } + // we first evaluate methods of the subclass and then move to the parent + Method[] declaredMethods = pClass.getDeclaredMethods(); + for (Method declaredMethod : declaredMethods) { + int modifiers = declaredMethod.getModifiers(); + if ((!Modifier.isPublic(modifiers) && !Modifier.isProtected(modifiers)) || Modifier.isStatic(modifiers)) { + continue; + } + if (methods.size() == 0) { + methods.add(declaredMethod); + } else { + List<Method> temp = new ArrayList<Method>(); + boolean matched = false; + for (Method method : methods) { + // only add if not already in the set from a supclass (i.e. the + // method is not overrided) + if (exactMethodMatch(declaredMethod, method)) { + matched = true; + break; + } + } + if (!matched) { + // TODO ignore Java accessibility + declaredMethod.setAccessible(true); + temp.add(declaredMethod); + } + methods.addAll(temp); + temp.clear(); + } + } + // evaluate class hierarchy - this is done last to track inherited methods + methods = getAllUniqueMethods(pClass.getSuperclass(), methods); + return methods; + } + + /** + * Finds the closest matching field with the given name, that is, a field of the exact specified type or, + * alternately, of a supertype. + * + * @param name the name of the field + * @param type the field type + * @param fields the collection of fields to search + * @return the matching field or null if not found + */ + public static Field findClosestMatchingField(String name, Class type, Set<Field> fields) { + Field candidate = null; + for (Field field : fields) { + if (field.getName().equals(name)) { + if (field.getType().equals(type)) { + return field; // exact match + } else if (field.getType().isAssignableFrom(type) + || (field.getType().isPrimitive() && primitiveAssignable(field.getType(), type))) { + // We could have the situation where a field parameter is a primitive and the demarshalled value is + // an object counterpart (e.g. Integer and int) + // @spec issue + // either an interface or super class, so keep a reference until + // we know there are no closer types + candidate = field; + } + } + } + if (candidate != null) { + return candidate; + } else { + return null; + } + } + + /** + * Finds the closest matching method with the given name, that is, a method taking the exact parameter types or, + * alternately, parameter supertypes. + * + * @param name the name of the method + * @param types the method parameter types + * @param methods the collection of methods to search + * @return the matching method or null if not found + */ + public static Method findClosestMatchingMethod(String name, Class[] types, Set<Method> methods) { + if (types == null) { + types = EMPTY_CLASS_ARRY; + } + Method candidate = null; + for (Method method : methods) { + if (method.getName().equals(name) && method.getParameterTypes().length == types.length) { + Class<?>[] params = method.getParameterTypes(); + boolean disqualify = false; + boolean exactMatch = true; + for (int i = 0; i < params.length; i++) { + if (!params[i].equals(types[i]) && !params[i].isAssignableFrom(types[i])) { + // no match + disqualify = true; + exactMatch = false; + break; + } else if (!params[i].equals(types[i]) && params[i].isAssignableFrom(types[i])) { + // not exact match + exactMatch = false; + } + } + if (disqualify) { + continue; + } else if (exactMatch) { + return method; + } else { + candidate = method; + } + } + } + if (candidate != null) { + return candidate; + } else { + return null; + } + } + + /** + * Searches a collection of fields for one that matches by name and has a multiplicity type. i.e. a List or Array of + * interfaces + * + * @return a matching field or null + */ + public static Field findMultiplicityFieldByName(String name, Set<Field> fields) { + for (Field candidate : fields) { + if (candidate.getName().equals(name) + && (List.class.isAssignableFrom(candidate.getType()) || (candidate.getType().isArray() + && candidate.getType().getComponentType() != null && candidate.getType().getComponentType() + .isInterface()))) { + return candidate; + } + } + return null; + } + + /** + * Searches a collection of method for one that matches by name and has single parameter of a multiplicity type. + * i.e. a List or Array of interfaces + * + * @return a matching method or null + */ + public static Method findMultiplicityMethodByName(String name, Set<Method> methods) { + for (Method candidate : methods) { + if (candidate.getName().equals(name) + && candidate.getParameterTypes().length == 1 + && (List.class.isAssignableFrom(candidate.getParameterTypes()[0]) + || (candidate.getParameterTypes()[0].isArray() + && candidate.getParameterTypes()[0].getComponentType() != null + && candidate.getParameterTypes()[0].getComponentType().isInterface()))) { + return candidate; + } + } + return null; + } + + /** + * Determines if two methods "match" - that is, they have the same method names and exact parameter types (one is + * not a supertype of the other) + */ + public static boolean exactMethodMatch(Method method1, Method method2) { + if (!method1.getName().equals(method2.getName())) { + return false; + } + Class[] types1 = method1.getParameterTypes(); + Class[] types2 = method2.getParameterTypes(); + if (types1.length == 0 && types2.length == 0) { + return true; + } else if (types1.length == types2.length) { + for (int n = 0; n < types1.length; n++) { + if (!types1[n].equals(types2[n])) { + return false; + } + } + return true; + } + return false; + } + + public static <T> Constructor<T> getDefaultConstructor(Class<T> clazz) throws NoSuchMethodException { + return clazz.getConstructor((Class[]) null); + } + + /** + * Loads a class corresponding to the class name using the current context class loader. + * + * @throws ClassNotFoundException if the class was not found on the classpath + */ + public static Class loadClass(String pName) throws ClassNotFoundException { + ClassLoader loader = Thread.currentThread().getContextClassLoader(); + return Class.forName(pName, true, loader); + } + + /** + * Returns the simple name of a class - i.e. the class name devoid of its package qualifier + * + * @param implClass the implmentation class + */ + public static String getBaseName(Class<?> implClass) { + String baseName = implClass.getName(); + int lastDot = baseName.lastIndexOf('.'); + if (lastDot != -1) { + baseName = baseName.substring(lastDot + 1); + } + return baseName; + } + + public static boolean isImmutable(Class clazz) { + return String.class == clazz + || clazz.isPrimitive() + || Number.class.isAssignableFrom(clazz) + || Boolean.class.isAssignableFrom(clazz) + || Character.class.isAssignableFrom(clazz) + || Byte.class.isAssignableFrom(clazz); + } + + /** + * Takes a property name and converts it to a getter method name according to JavaBean conventions. For example, + * property <code>foo<code> is returned as <code>getFoo</code> + */ + public static String toGetter(String name) { + return "get" + name.toUpperCase().substring(0, 1) + name.substring(1); + } + + /** + * Takes a setter or getter method name and converts it to a property name according to JavaBean conventions. For + * example, <code>setFoo(var)</code> is returned as property <code>foo<code> + */ + public static String toPropertyName(String name) { + if (!name.startsWith("set")) { + return name; + } + return Character.toLowerCase(name.charAt(3)) + name.substring(4); + } + + /** + * Takes a property name and converts it to a setter method name according to JavaBean conventions. For example, the + * property <code>foo<code> is returned as <code>setFoo(var)</code> + */ + public static String toSetter(String name) { + return "set" + name.toUpperCase().substring(0, 1) + name.substring(1); + } + + /** + * Compares a two types, assuming one is a primitive, to determine if the other is its object counterpart + */ + private static boolean primitiveAssignable(Class memberType, Class param) { + if (memberType == Integer.class) { + return param == Integer.TYPE; + } else if (memberType == Double.class) { + return param == Double.TYPE; + } else if (memberType == Float.class) { + return param == Float.TYPE; + } else if (memberType == Short.class) { + return param == Short.TYPE; + } else if (memberType == Character.class) { + return param == Character.TYPE; + } else if (memberType == Boolean.class) { + return param == Boolean.TYPE; + } else if (memberType == Byte.class) { + return param == Byte.TYPE; + } else if (param == Integer.class) { + return memberType == Integer.TYPE; + } else if (param == Double.class) { + return memberType == Double.TYPE; + } else if (param == Float.class) { + return memberType == Float.TYPE; + } else if (param == Short.class) { + return memberType == Short.TYPE; + } else if (param == Character.class) { + return memberType == Character.TYPE; + } else if (param == Boolean.class) { + return memberType == Boolean.TYPE; + } else if (param == Byte.class) { + return memberType == Byte.TYPE; + } else { + return false; + } + } + + /** + * Returns the generic types represented in the given type. Usage as follows: <code> + * JavaIntrospectionHelper.getGenerics(field.getGenericType()); + * <p/> + * JavaIntrospectionHelper.getGenerics(m.getGenericParameterTypes()[0];); </code> + * + * @return the generic types in order of declaration or an empty array if the type is not genericized + */ + public static List<? extends Type> getGenerics(Type genericType) { + List<Type> classes = new ArrayList<Type>(); + if (genericType instanceof ParameterizedType) { + ParameterizedType ptype = (ParameterizedType) genericType; + // get the type arguments + Type[] targs = ptype.getActualTypeArguments(); + for (Type targ : targs) { + classes.add(targ); + } + } + return classes; + } + + /** + * Returns the generic type specified by the class at the given position as in: + * <p/> + * <code> public class Foo<Bar,Baz>{ //.. } + * <p/> + * JavaIntrospectionHelper.introspectGeneric(Foo.class,1); <code> + * <p/> + * will return Baz. + */ + public static Class introspectGeneric(Class<?> clazz, int pos) { + assert clazz != null : "No class specified"; + Type type = clazz.getGenericSuperclass(); + if (type instanceof ParameterizedType) { + Type[] args = ((ParameterizedType) type).getActualTypeArguments(); + if (args.length <= pos) { + throw new IllegalArgumentException("Invalid index value for generic class " + clazz.getName()); + } + return (Class) ((ParameterizedType) type).getActualTypeArguments()[pos]; + } else { + Type[] interfaces = clazz.getGenericInterfaces(); + for (Type itype : interfaces) { + if (!(itype instanceof ParameterizedType)) { + continue; + } + ParameterizedType interfaceType = (ParameterizedType) itype; + return (Class) interfaceType.getActualTypeArguments()[0]; + } + } + return null; + } + + /** + * Returns the set of interfaces implemented by the given class and its ancestors or a blank set if none + */ + public static Set<Class> getAllInterfaces(Class clazz) { + Set<Class> implemented = new HashSet<Class>(); + getAllInterfaces(clazz, implemented); + return implemented; + } + + private static void getAllInterfaces(Class clazz, Set<Class> implemented) { + Class[] interfaces = clazz.getInterfaces(); + for (Class interfaze : interfaces) { + implemented.add(interfaze); + } + Class<?> superClass = clazz.getSuperclass(); + // Object has no superclass so check for null + if (superClass != null && !superClass.equals(Object.class)) { + getAllInterfaces(superClass, implemented); + } + } + +} |