Hibernate example source code file (PreparedStatementProxy.java)

This example Hibernate source code file (PreparedStatementProxy.java) is included in the DevDaily.com "Java Source Code Warehouse" project. The intent of this project is to help you "Learn Java by Example" ^TM.

Java - Hibernate tags/keywords

classloader, invocationhandler, jdbc, object, override, preparedstatement, preparedstatement, preparedstatementproxy, preparedstatementproxy, reflection, sql, sqlexception, string, string, t, t, throwable

The Hibernate PreparedStatementProxy.java source code

/*
 * Hibernate, Relational Persistence for Idiomatic Java
 *
 * Copyright (c) 2010, Red Hat Inc. or third-party contributors as
 * indicated by the @author tags or express copyright attribution
 * statements applied by the authors.  All third-party contributions are
 * distributed under license by Red Hat Inc.
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * This program 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 distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */
package org.hibernate.type.descriptor.sql;
import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;
import java.lang.reflect.Proxy;
import java.sql.Clob;
import java.sql.PreparedStatement;
import java.sql.SQLException;
import junit.framework.Assert;

/**
 * TODO : javadoc
 *
 * @author Steve Ebersole
 */
public class PreparedStatementProxy<T> implements InvocationHandler {
	public static PreparedStatement generateProxy(PreparedStatementProxy handler) {
		return (PreparedStatement) Proxy.newProxyInstance(
				getProxyClassLoader(),
				new Class[] { PreparedStatement.class },
				handler
		);
	}

	private static ClassLoader getProxyClassLoader() {
		ClassLoader cl = Thread.currentThread().getContextClassLoader();
		if ( cl == null ) {
			cl = PreparedStatement.class.getClassLoader();
		}
		return cl;
	}

	@SuppressWarnings({ "unchecked" })
	public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
		if ( value == null ) {
			Assert.assertEquals( "Expecting setNull call", "setNull", method.getName() );
			return null;
		}
		if ( method.getName().equals( methodName ) && args.length >= 1 ) {
			checkValue( (T) args[1] );
			return null;
		}
		throw new UnsupportedOperationException( "Unexpected call PreparedStatement." + method.getName() );
	}

	protected void checkValue(T arg) throws SQLException {
		Assert.assertEquals( value, arg );
	}

	protected final String extractString(Clob clob) throws SQLException {
		if ( StringClobImpl.class.isInstance( clob ) ) {
			return ( (StringClobImpl) clob ).getValue();
		}
		return clob.getSubString( 1, (int)clob.length() );
	}

	private final String methodName;
	private final T value;

	public T getValue() {
		return value;
	}

	protected PreparedStatementProxy(String methodName, T value) {
		this.methodName = methodName;
		this.value = value;
	}

	public static PreparedStatement generateProxy(final String value) {
		return generateProxy(
				new PreparedStatementProxy<String>( "setString", value )
		);
	}

	public static PreparedStatement generateProxy(Clob value) {
		return generateProxy(
				new PreparedStatementProxy<Clob>( "setClob", value ) {
					@Override
					protected void checkValue(Clob arg) throws SQLException {
						Assert.assertEquals( extractString( getValue() ), extractString( arg ) );
					}
				}
		);
	}
}