reflectgeneratedclass.java

derby database source code.good for you.

/*

   Derby - Class org.apache.derby.impl.services.reflect.ReflectGeneratedClass

   Copyright 1998, 2004 The Apache Software Foundation or its licensors, as applicable.

   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 org.apache.derby.impl.services.reflect;

import org.apache.derby.iapi.services.loader.GeneratedMethod;
import org.apache.derby.iapi.services.loader.GeneratedByteCode;
import org.apache.derby.iapi.services.loader.ClassFactory;

import org.apache.derby.iapi.error.StandardException;
import org.apache.derby.iapi.reference.SQLState;

import org.apache.derby.iapi.services.context.Context;

import java.lang.reflect.Method;
import java.util.Hashtable;

public final class ReflectGeneratedClass extends LoadedGeneratedClass {

	private final Hashtable methodCache;
	private static final GeneratedMethod[] directs;


	private final Class	factoryClass;
	private GCInstanceFactory factory;

	static {
		directs = new GeneratedMethod[10];
		for (int i = 0; i < directs.length; i++) {
			directs[i] = new DirectCall(i);
		}
	}

	public ReflectGeneratedClass(ClassFactory cf, Class jvmClass, Class factoryClass) {
		super(cf, jvmClass);
		methodCache = new Hashtable();
		this.factoryClass = factoryClass;
	}

	public Object newInstance(Context context) throws StandardException	{
		if (factoryClass == null) {
			return super.newInstance(context);
		}

		if (factory == null) {

			Throwable t;
			try {
				factory =  (GCInstanceFactory) factoryClass.newInstance();
				t = null;
			} catch (InstantiationException ie) {
				t = ie;
			} catch (IllegalAccessException iae) {
				t = iae;
			} catch (LinkageError le) {
				t = le;
			}

			if (t != null)
				throw StandardException.newException(SQLState.GENERATED_CLASS_INSTANCE_ERROR, t, getName());
		}

		GeneratedByteCode ni = factory.getNewInstance();
		ni.initFromContext(context);
		ni.setGC(this);
		ni.postConstructor();
		return ni;

	}

	public GeneratedMethod getMethod(String simpleName)
		throws StandardException {

		GeneratedMethod rm = (GeneratedMethod) methodCache.get(simpleName);
		if (rm != null)
			return rm;

		// Only look for methods that take no arguments
		try {
			if ((simpleName.length() == 2) && simpleName.startsWith("e")) {

				int id = ((int) simpleName.charAt(1)) - '0';

				rm = directs[id];


			}
			else
			{
				Method m = getJVMClass().getMethod(simpleName, (Class []) null);
				
				rm = new ReflectMethod(m);
			}
			methodCache.put(simpleName, rm);
			return rm;

		} catch (NoSuchMethodException nsme) {
			throw StandardException.newException(SQLState.GENERATED_CLASS_NO_SUCH_METHOD,
				nsme, getName(), simpleName);
		}
	}
}

class DirectCall implements GeneratedMethod {

	private final int which;

	DirectCall(int which) {

		this.which = which;
	}

	public Object invoke(Object ref)
		throws StandardException {

		try {

			GeneratedByteCode gref = (GeneratedByteCode) ref;
			switch (which) {
			case 0:
				return gref.e0();
			case 1:
				return gref.e1();
			case 2:
				return gref.e2();
			case 3:
				return gref.e3();
			case 4:
				return gref.e4();
			case 5:
				return gref.e5();
			case 6:
				return gref.e6();
			case 7:
				return gref.e7();
			case 8:
				return gref.e8();
			case 9:
				return gref.e9();
			}
			return null;
		} catch (StandardException se) {
			throw se;
		}		
		catch (Throwable t) {
			throw StandardException.unexpectedUserException(t);
		}
	}
}