_statement.java

JSP开发的博客管理系统,使用struts+hibernate+AJAX技术

/*
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  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 Library General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
package web.struts;

import java.lang.reflect.*;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.Statement;

/**
 * 数据库语句对象的代理
 * @author Winter Lau
 */
class _Statement implements InvocationHandler {

	private final static Class[] infs = new Class[]{Statement.class};
	private final static Class[] infs2 = new Class[]{PreparedStatement.class};

	public _Statement(Statement stmt, boolean decode) {
		statement = stmt;
		this.decode = decode;
	}

	/**
	 * 获取Statement实例的代理
	 * @return
	 */
	public Statement getStatement() {
		if(statement instanceof PreparedStatement)
		return (Statement)Proxy.newProxyInstance(
			statement.getClass().getClassLoader(),infs2, this);
		return (Statement)Proxy.newProxyInstance(
				statement.getClass().getClassLoader(),infs, this);
	}

	public Object invoke(Object proxy, Method m, Object args[])	throws Throwable {
		String method = m.getName();
		if (decode && SETSTRING.equals(method))
			try {
				String param = (String) args[1];
				if (param != null)
					param = new String(param.getBytes(), "8859_1");
				return m.invoke(statement, new Object[] { args[0], param });
			} catch (InvocationTargetException e) {
				throw e.getTargetException();
			}
		if (decode && EXECUTEQUERY.equals(method))
			try {
				ResultSet rs = (ResultSet) m.invoke(statement, args);
				return (new _ResultSet(rs, decode)).getResultSet();
			} catch (InvocationTargetException e) {
				throw e.getTargetException();
			}
		try {
			return m.invoke(statement, args);
		} catch (InvocationTargetException e) {
			if (GETQUERYTIMEOUT.equals(method))
				return new Integer(0);
			else
				throw e.getTargetException();
		}
	}

	private Statement statement;

	private boolean decode;

	private static final String GETQUERYTIMEOUT = "getQueryTimeout";

	private static final int gqt_return = 0;

	private static final String SETSTRING = "setString";

	private static final String EXECUTEQUERY = "executeQuery";
}