classutils.java

EasyDBO是一个超轻量级对象-关系映射（Object/Relation Mapping

/*
 * Copyright 2002-2006 the original author or authors.
 *
 * Licensed 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 com.easyjf.util;

import java.beans.Introspector;
import java.lang.reflect.Array;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;

import org.apache.log4j.Logger;



/**
 * Miscellaneous class utility methods. Mainly for internal use within the
 * framework; consider Jakarta's Commons Lang for a more comprehensive suite
 * of utilities.
 *
 * @author Keith Donald
 * @author Rob Harrop
 * @author Juergen Hoeller
 * @since 1.1
 */
public abstract class ClassUtils {

	/** Suffix for array class names */
	public static final String ARRAY_SUFFIX = "[]";

	/** The package separator character '.' */
	private static final char PACKAGE_SEPARATOR_CHAR = '.';

	/** The inner class separator character '$' */
	private static final char INNER_CLASS_SEPARATOR_CHAR = '$';

	/** The CGLIB class separator character "$$" */
	private static final String CGLIB_CLASS_SEPARATOR_CHAR = "$$";

	private final static Logger logger = Logger.getLogger(ClassUtils.class);	

	/**
	 * Map with primitive wrapper type as key and corresponding primitive
	 * type as value, for example: Integer.class -> int.class.
	 */
	private static final Map primitiveWrapperTypeMap = new HashMap(8);

	/**
	 * Map with primitive type name as key and corresponding primitive
	 * type as value, for example: "int" -> "int.class".
	 */
	private static final Map primitiveTypeNameMap = new HashMap(8);

	static {
		primitiveWrapperTypeMap.put(Boolean.class, boolean.class);
		primitiveWrapperTypeMap.put(Byte.class, byte.class);
		primitiveWrapperTypeMap.put(Character.class, char.class);
		primitiveWrapperTypeMap.put(Double.class, double.class);
		primitiveWrapperTypeMap.put(Float.class, float.class);
		primitiveWrapperTypeMap.put(Integer.class, int.class);
		primitiveWrapperTypeMap.put(Long.class, long.class);
		primitiveWrapperTypeMap.put(Short.class, short.class);

		for (Iterator it = primitiveWrapperTypeMap.values().iterator(); it.hasNext();) {
			Class primitiveClass = (Class) it.next();
			primitiveTypeNameMap.put(primitiveClass.getName(), primitiveClass);
		}
	}


	/**
	 * Return a default ClassLoader to use (never <code>null</code>).
	 * Returns the thread context ClassLoader, if available.
	 * The ClassLoader that loaded the ClassUtils class will be used as fallback.
	 * <p>Call this method if you intend to use the thread context ClassLoader
	 * in a scenario where you absolutely need a non-null ClassLoader reference:
	 * for example, for class path resource loading (but not necessarily for
	 * <code>Class.forName</code>, which accepts a <code>null</code> ClassLoader
	 * reference as well).
	 * @see Thread#getContextClassLoader()
	 */
	public static ClassLoader getDefaultClassLoader() {
		ClassLoader cl = Thread.currentThread().getContextClassLoader();
		if (cl == null) {
			// No thread context class loader -> use class loader of this class.
			cl = ClassUtils.class.getClassLoader();
		}
		return cl;
	}

	/**
	 * Return whether the {@link Class} identified by the supplied name is present
	 * and can be loaded. Will return <code>false</code> if either the class or
	 * one of its dependencies is not present or cannot be loaded.
	 */
	public static boolean isPresent(String className) {
		try {
			forName(className);
			return true;
		}
		catch (Throwable ex) {
			if (logger.isDebugEnabled()) {
				logger.debug("Class [" + className + "] or one of its dependencies is not present: " + ex);
			}
			return false;
		}
	}

	/**
	 * Replacement for <code>Class.forName()</code> that also returns Class instances
	 * for primitives (like "int") and array class names (like "String[]").
	 * <p>Always uses the default class loader: that is, preferably the thread context
	 * class loader, or the ClassLoader that loaded the ClassUtils class as fallback.
	 * @param name the name of the Class
	 * @return Class instance for the supplied name
	 * @see Class#forName(String, boolean, ClassLoader)
	 * @see #getDefaultClassLoader()
	 */
	public static Class forName(String name) throws ClassNotFoundException {
		return forName(name, getDefaultClassLoader());
	}

	/**
	 * Replacement for <code>Class.forName()</code> that also returns Class instances
	 * for primitives (like "int") and array class names (like "String[]").
	 * @param name the name of the Class
	 * @param classLoader the class loader to use
	 * @return Class instance for the supplied name
	 * @see Class#forName(String, boolean, ClassLoader)
	 */
	public static Class forName(String name, ClassLoader classLoader) throws ClassNotFoundException {
		Class clazz = resolvePrimitiveClassName(name);
		if (clazz != null) {
			return clazz;
		}
		if (name.endsWith(ARRAY_SUFFIX)) {
			// special handling for array class names
			String elementClassName = name.substring(0, name.length() - ARRAY_SUFFIX.length());
			Class elementClass = ClassUtils.forName(elementClassName, classLoader);
			return Array.newInstance(elementClass, 0).getClass();
		}
		return Class.forName(name, true, classLoader);
	}

	/**
	 * Resolve the given class name as primitive class, if appropriate.
	 * @param name the name of the potentially primitive class
	 * @return the primitive class, or <code>null</code> if the name does not denote
	 * a primitive class
	 */
	public static Class resolvePrimitiveClassName(String name) {
		Class result = null;
		// Most class names will be quite long, considering that they
		// SHOULD sit in a package, so a length check is worthwhile.
		if (name != null && name.length() <= 8) {
			// Could be a primitive - likely.
			result = (Class) primitiveTypeNameMap.get(name);
		}
		return result;
	}

	/**
	 * Get the class name without the qualified package name.
	 * @param className the className to get the short name for
	 * @return the class name of the class without the package name
	 * @throws IllegalArgumentException if the className is empty
	 */
	public static String getShortName(String className) {
		Assert.hasLength(className, "Class name must not be empty");
		int lastDotIndex = className.lastIndexOf(PACKAGE_SEPARATOR_CHAR);
		int nameEndIndex = className.indexOf(CGLIB_CLASS_SEPARATOR_CHAR);
		if (nameEndIndex == -1) {
			nameEndIndex = className.length();
		}
		String shortName = className.substring(lastDotIndex + 1, nameEndIndex);
		shortName = shortName.replace(INNER_CLASS_SEPARATOR_CHAR, PACKAGE_SEPARATOR_CHAR);
		return shortName;
	}

	/**
	 * Get the class name without the qualified package name.
	 * @param clazz the class to get the short name for
	 * @return the class name of the class without the package name
	 */
	public static String getShortName(Class clazz) {
		return getShortName(getQualifiedName(clazz));
	}

	/**
	 * Return the short string name of a Java class in decapitalized
	 * JavaBeans property format.
	 * @param clazz the class
	 * @return the short name rendered in a standard JavaBeans property format
	 * @see java.beans.Introspector#decapitalize(String)
	 */
	public static String getShortNameAsProperty(Class clazz) {
		return Introspector.decapitalize(getShortName(clazz));
	}

	/**
	 * Return the qualified name of the given class: usually simply
	 * the class name, but component type class name + "[]" for arrays.
	 * @param clazz the class
	 * @return the qualified name of the class
	 */
	public static String getQualifiedName(Class clazz) {
		Assert.notNull(clazz, "Class must not be null");
		if (clazz.isArray()) {
            return getQualifiedNameForArray(clazz);
		}
		else {
			return clazz.getName();
		}
	}


	/**
	 * Return the qualified name of the given method, consisting of
	 * fully qualified interface/class name + "." + method name.
	 * @param method the method
	 * @return the qualified name of the method
	 */
	public static String getQualifiedMethodName(Method method) {
		Assert.notNull(method, "Method must not be null");
		return method.getDeclaringClass().getName() + "." + method.getName();
	}

	/**
	 * Determine whether the given class has a method with the given signature.
	 * Essentially translates <code>NoSuchMethodException</code> to "false".
	 * @param clazz	the clazz to analyze
	 * @param methodName the name of the method
	 * @param paramTypes the parameter types of the method
	 */
	public static boolean hasMethod(Class clazz, String methodName, Class[] paramTypes) {
		Assert.notNull(clazz, "Class must not be null");
		Assert.notNull(methodName, "Method name must not be null");
		try {