classutils.java

来自「c3p0数据库连接池实现源码」· Java 代码 · 共 210 行

/*
 * Distributed as part of c3p0 v.0.9.1-pre6
 *
 * Copyright (C) 2005 Machinery For Change, Inc.
 *
 * Author: Steve Waldman <[e-mail]>
 *
 * This library is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1, as 
 * published by the Free Software Foundation.
 *
 * This software 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 Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this software; see the file LICENSE.  If not, write to the
 * Free Software Foundation, Inc., 59 Temple Place, Suite 330,
 * Boston, MA 02111-1307, USA.
 */


package com.mchange.v1.lang;

import java.util.*;
import com.mchange.v1.jvm.*;

public final class ClassUtils
{
    final static String[] EMPTY_SA = new String[0];

    static Map primitivesToClasses;

    static
    {
	HashMap tmp = new HashMap();
	tmp.put( "boolean", boolean.class );
	tmp.put( "int", int.class );
	tmp.put( "char", char.class );
	tmp.put( "short", short.class );
	tmp.put( "int", int.class );
	tmp.put( "long", long.class );
	tmp.put( "float", float.class );
	tmp.put( "double", double.class );
	tmp.put( "void", void.class );

	primitivesToClasses = Collections.unmodifiableMap( tmp );
    }

    public static Set allAssignableFrom(Class type)
    {
	Set out = new HashSet();

	//type itself and superclasses (if any)
	for (Class cl = type; cl != null; cl = cl.getSuperclass())
	    out.add( cl );

	//super interfaces (if any)
	addSuperInterfacesToSet( type, out );
	return out;
    }

    public static String simpleClassName(Class cl)
    {
	String scn;
	int array_level = 0;
	while (cl.isArray())
	    {
		++array_level;
		cl = cl.getComponentType();
	    }
	scn = simpleClassName( cl.getName() );
	if ( array_level > 0 )
	    {
		StringBuffer sb = new StringBuffer(16);
		sb.append( scn );
		for( int i = 0; i < array_level; ++i)
		    sb.append("[]");
		return sb.toString();
	    }
	else
	    return scn;
    }

    private static String simpleClassName(String fqcn)
    {
       int pkgdot = fqcn.lastIndexOf('.');
       if (pkgdot < 0)
          return fqcn;
       String scn = fqcn.substring(pkgdot + 1);
       if (scn.indexOf('$') >= 0)
          {
             StringBuffer sb = new StringBuffer(scn);
             for (int i = 0, len = sb.length(); i < len; ++i)
             {
                 if (sb.charAt(i) == '$')
                   sb.setCharAt(i, '.');
             }
             return sb.toString();
          }
       else
         return scn;
    }

    public static boolean isPrimitive(String typeStr)
    { return (primitivesToClasses.get( typeStr ) != null); }

    public static Class classForPrimitive(String typeStr)
    { return (Class) primitivesToClasses.get( typeStr ); }

    public static Class forName( String fqOrSimple,  String[] importPkgs, String[] importClasses )
	throws AmbiguousClassNameException, ClassNotFoundException
    {
	try
	    { return Class.forName( fqOrSimple ); }
	catch ( ClassNotFoundException e )
	    { return classForSimpleName( fqOrSimple, importPkgs, importClasses ); }
    }

    public static Class classForSimpleName( String simpleName, String[] importPkgs, String[] importClasses )
	throws AmbiguousClassNameException, ClassNotFoundException
    {
	Set checkSet = new HashSet();
	Class out = classForPrimitive( simpleName );

	if (out == null)
	    {
		if (importPkgs == null)
		    importPkgs = EMPTY_SA;
		
		if (importClasses == null)
		    importClasses = EMPTY_SA;
		
		for (int i = 0, len = importClasses.length; i < len; ++i)
		    {
			String importSimpleName = fqcnLastElement( importClasses[i] );
			if (! checkSet.add( importSimpleName ) )
			    throw new IllegalArgumentException("Duplicate imported classes: " + 
							       importSimpleName);
			if ( simpleName.equals( importSimpleName ) ) 
			    //we won't duplicate assign. we'd have caught it above
			    out = Class.forName( importClasses[i] );
		    }
		if (out == null)
		    {
			try { out = Class.forName("java.lang." + simpleName); }
			catch (ClassNotFoundException e)
			    { /* just means we haven't found it yet */ }

			for (int i = 0, len = importPkgs.length; i < len; ++i)
			    {
				try
				    {
					String tryClass = importPkgs[i] + '.' + simpleName;
					Class test = Class.forName( tryClass );
					if ( out == null )
					    out = test;
					else
					    throw new AmbiguousClassNameException( simpleName, out, test );
				    }
				catch (ClassNotFoundException e)
				    { /* just means we haven't found it yet */ }
			    }
		    }
	    }
	if (out == null)
	    throw new ClassNotFoundException( "Could not find a class whose unqualified name is \042" +
					      simpleName + "\042 with the imports supplied. Import packages are " +
					      Arrays.asList( importPkgs ) + "; class imports are " +
					      Arrays.asList( importClasses ) );
	else
	    return out;
    }

    public static String resolvableTypeName( Class type, String[] importPkgs, String[] importClasses )
	throws ClassNotFoundException
    {
	String simpleName = simpleClassName( type );
	try
	    { classForSimpleName( simpleName, importPkgs, importClasses ); }
	catch ( AmbiguousClassNameException e )
	    { return type.getName(); }
	return simpleName;
    }

    public static String fqcnLastElement(String fqcn)
    {
       int pkgdot = fqcn.lastIndexOf('.');
       if (pkgdot < 0)
          return fqcn;
       return fqcn.substring(pkgdot + 1);
    }


    /* does not add type itself, only its superinterfaces */
    private static void addSuperInterfacesToSet(Class type, Set set)
    {
	Class[] ifaces = type.getInterfaces();
	for (int i = 0, len = ifaces.length; i < len; ++i)
	    {
		set.add( ifaces[i] );
		addSuperInterfacesToSet( ifaces[i], set );
	    }
    }

    private ClassUtils()
    {}
}