jdk/src/share/classes/com/sun/beans/finder/ClassFinder.java

/*
 * Copyright 2006 Sun Microsystems, Inc.  All Rights Reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Sun designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Sun in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Sun Microsystems, Inc., 4150 Network Circle, Santa Clara,
 * CA 95054 USA or visit www.sun.com if you need additional information or
 * have any questions.
 */
package com.sun.beans.finder;

/**
 * This is utility class that provides <code>static</code> methods
 * to find a class with the specified name using the specified class loader.
 *
 * @since 1.7
 *
 * @author Sergey A. Malenkov
 */
public final class ClassFinder {
    /**
     * Returns the <code>Class</code> object associated
     * with the class or interface with the given string name,
     * using the default class loader.
     * <p>
     * The <code>name</code> can denote an array class
     * (see {@link Class#getName} for details).
     *
     * @param name  fully qualified name of the desired class
     * @return class object representing the desired class
     *
     * @exception ClassNotFoundException  if the class cannot be located
     *                                    by the specified class loader
     *
     * @see Class#forName(String)
     * @see Class#forName(String,boolean,ClassLoader)
     * @see ClassLoader#getSystemClassLoader()
     * @see Thread#getContextClassLoader()
     */
    public static Class findClass( String name ) throws ClassNotFoundException {
        try {
            ClassLoader loader = Thread.currentThread().getContextClassLoader();
            if ( loader == null ) {
                // can be null in IE (see 6204697)
                loader = ClassLoader.getSystemClassLoader();
            }
            if ( loader != null ) {
                return Class.forName( name, false, loader );
            }

        } catch ( ClassNotFoundException exception ) {
            // use current class loader instead
        } catch ( SecurityException exception ) {
            // use current class loader instead
        }
        return Class.forName( name );
    }

    /**
     * Returns the <code>Class</code> object associated with
     * the class or interface with the given string name,
     * using the given class loader.
     * <p>
     * The <code>name</code> can denote an array class
     * (see {@link Class#getName} for details).
     * <p>
     * If the parameter <code>loader</code> is null,
     * the class is loaded through the default class loader.
     *
     * @param name    fully qualified name of the desired class
     * @param loader  class loader from which the class must be loaded
     * @return class object representing the desired class
     *
     * @exception ClassNotFoundException  if the class cannot be located
     *                                    by the specified class loader
     *
     * @see #findClass(String,ClassLoader)
     * @see Class#forName(String,boolean,ClassLoader)
     */
    public static Class findClass( String name, ClassLoader loader ) throws ClassNotFoundException {
        if ( loader != null ) {
            try {
                return Class.forName( name, false, loader );
            } catch ( ClassNotFoundException exception ) {
                // use default class loader instead
            } catch ( SecurityException exception ) {
                // use default class loader instead
            }
        }
        return findClass( name );
    }

    /**
     * Returns the <code>Class</code> object associated
     * with the class or interface with the given string name,
     * using the default class loader.
     * <p>
     * The <code>name</code> can denote an array class
     * (see {@link Class#getName} for details).
     * <p>
     * This method can be used to obtain
     * any of the <code>Class</code> objects
     * representing <code>void</code> or primitive Java types:
     * <code>char</code>, <code>byte</code>, <code>short</code>,
     * <code>int</code>, <code>long</code>, <code>float</code>,
     * <code>double</code> and <code>boolean</code>.
     *
     * @param name  fully qualified name of the desired class
     * @return class object representing the desired class
     *
     * @exception ClassNotFoundException  if the class cannot be located
     *                                    by the specified class loader
     *
     * @see #resolveClass(String,ClassLoader)
     */
    public static Class resolveClass( String name ) throws ClassNotFoundException {
        return resolveClass( name, null );
    }

    /**
     * Returns the <code>Class</code> object associated with
     * the class or interface with the given string name,
     * using the given class loader.
     * <p>
     * The <code>name</code> can denote an array class
     * (see {@link Class#getName} for details).
     * <p>
     * If the parameter <code>loader</code> is null,
     * the class is loaded through the default class loader.
     * <p>
     * This method can be used to obtain
     * any of the <code>Class</code> objects
     * representing <code>void</code> or primitive Java types:
     * <code>char</code>, <code>byte</code>, <code>short</code>,
     * <code>int</code>, <code>long</code>, <code>float</code>,
     * <code>double</code> and <code>boolean</code>.
     *
     * @param name    fully qualified name of the desired class
     * @param loader  class loader from which the class must be loaded
     * @return class object representing the desired class
     *
     * @exception ClassNotFoundException  if the class cannot be located
     *                                    by the specified class loader
     *
     * @see #findClass(String,ClassLoader)
     * @see PrimitiveTypeMap#getType(String)
     */
    public static Class resolveClass( String name, ClassLoader loader ) throws ClassNotFoundException {
        Class type = PrimitiveTypeMap.getType( name );
        return ( type == null )
                ? findClass( name, loader )
                : type;
    }

    /**
     * Disable instantiation.
     */
    private ClassFinder() {
    }
}