escapeprocessor.java

Java写的TDS协议(JDBC/ODBC)实现

//
// Copyright 1998 CDS Networks, Inc., Medford Oregon
//
// All rights reserved.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
// 3. All advertising materials mentioning features or use of this software
//    must display the following acknowledgement:
//      This product includes software developed by CDS Networks, Inc.
// 4. The name of CDS Networks, Inc.  may not be used to endorse or promote
//    products derived from this software without specific prior
//    written permission.
//
// THIS SOFTWARE IS PROVIDED BY CDS NETWORKS, INC. ``AS IS'' AND
// ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL CDS NETWORKS, INC. BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
// LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
// OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
// SUCH DAMAGE.
//

package net.sourceforge.jtds.jdbc;

import java.sql.*;

abstract public class EscapeProcessor
{
    public static final String cvsVersion = "$Id: EscapeProcessor.java,v 1.4 2002/10/22 09:50:10 alin_sinpalean Exp $";

    String   input;
    private static final String ESCAPE_PREFIX_DATE = "d ";
    private static final String ESCAPE_PREFIX_TIME = "t ";
    private static final String ESCAPE_PREFIX_TIMESTAMP = "ts ";
    private static final String ESCAPE_PREFIX_OUTER_JOIN = "oj ";
    private static final String ESCAPE_PREFIX_FUNCTION = "fn ";
    private static final String ESCAPE_PREFIX_CALL = "call ";
    private static final String ESCAPE_PREFIX_ESCAPE_CHAR = "escape ";

    public EscapeProcessor(String sql)
    {
        input = sql;
    }

    abstract public String expandDBSpecificFunction(String escapeSequence) throws SQLException;

    /**
     * Is the string made up only of digits?
     * <p>
     * <b>Note:</b>  Leading/trailing spaces or signs are not considered digits.
     *
     * @return true if the string has only digits, false otherwise.
     */
    private static boolean validDigits(String str)
    {
        for( int i=0; i<str.length(); i++ )
            if( !Character.isDigit(str.charAt(i)) )
                return false;

        return true;
    }

    /**
     * Given a string and an index into that string return the index
     * of the next non-whitespace character.
     *
     * @return index of next non-whitespace character.
     */
    private static int skipWhitespace(String str, int i)
    {
        while( i<str.length() && Character.isWhitespace(str.charAt(i)) )
           i++;

        return i;
    }

    /**
     * Given a string and an index into that string, advanvance the index
     * iff it is on a quote character.
     *
     * @return the next position in the string iff the current character is a
     *         quote
     */
    private static int skipQuote(String str, int i)
    {
        // skip over the leading quote if it exists
        if( i<str.length() && (str.charAt(i)=='\'' || str.charAt(i)=='"') )
            // XXX Note-  The spec appears to prohibit the quote character,
            // but many drivers allow it.  We should probably control this
            // with a flag.
            i++;

        return i;
    }

    /**
     * Convert a JDBC SQL escape date sequence into a datestring recognized by SQLServer.
     */
    private static String getDate(String str) throws SQLException
    {
        int   i;

        // skip over the "d "
        i = 2;

        // skip any additional spaces
        i = skipWhitespace(str, i);

        i = skipQuote(str, i);

        // i is now up to the point where the date had better start.
        if( str.length()-i<10 || str.charAt(i+4)!='-' || str.charAt(i+7)!='-' )
            throw new SQLException("Malformed date");

        String year  = str.substring(i, i+4);
        String month = str.substring(i+5, i+5+2);
        String day   = str.substring(i+5+3, i+5+3+2);

        // Make sure the year, month, and day are numeric
        if( !validDigits(year) || !validDigits(month) || !validDigits(day) )
            throw new SQLException("Malformed date");

        // Make sure there isn't any garbage after the date
        i = i+10;
        i = skipWhitespace(str, i);
        i = skipQuote(str, i);
        i = skipWhitespace(str, i);

        if( i<str.length() )
            throw new SQLException("Malformed date");

        return "'" + year + month + day + "'";
    }

    /**
     * Convert a JDBC SQL escape time sequence into a time string recognized by SQLServer.
     */
    private static String getTime(String str) throws SQLException
    {
        int   i;

        // skip over the "t "
        i = 2;

        // skip any additional spaces
        i = skipWhitespace(str, i);

        i = skipQuote(str, i);

        // i is now up to the point where the date had better start.
        if( str.length()-i<8 || str.charAt(i+2)!=':' || str.charAt(i+5)!=':' )
            throw new SQLException("Malformed time");

        String hour   = str.substring(i, i+2);
        String minute = str.substring(i+3, i+3+2);
        String second = str.substring(i+3+3, i+3+3+2);

        // Make sure the year, month, and day are numeric
        if( !validDigits(hour) || !validDigits(minute) || !validDigits(second) )
            throw new SQLException("Malformed time");

        // Make sure there isn't any garbage after the time
        i = i+8;
        i = skipWhitespace(str, i);
        i = skipQuote(str, i);
        i = skipWhitespace(str, i);

        if( i<str.length() )
            throw new SQLException("Malformed time");

        return "'" + hour + ":" + minute + ":" + second + "'";
    }

    /**
     * Convert a JDBC SQL escape timestamp sequence into a date-time string recognized by SQLServer.
     */
    private static String getTimestamp(String str) throws SQLException
    {
        int   i;

        // skip over the "d "
        i = 2;

        // skip any additional spaces
        i = skipWhitespace(str, i);

        i = skipQuote(str, i);

        // i is now at the point where the date had better start.
        if( (str.length()-i)<19 || str.charAt(i+4)!='-' || str.charAt(i+7)!='-' )
            throw new SQLException("Malformed date");

        String year  = str.substring(i, i+4);
        String month = str.substring(i+5, i+5+2);
        String day   = str.substring(i+5+3, i+5+3+2);

        // Make sure the year, month, and day are numeric
        if( !validDigits(year) || !validDigits(month) || !validDigits(day) )
            throw new SQLException("Malformed date");

        // Make sure there is at least one space between date and time
        i = i+10;
        if( !Character.isWhitespace(str.charAt(i)) )
            throw new SQLException("Malformed date");

        // skip the whitespace
        i = skipWhitespace(str, i);

        // see if it could be a time
        if( str.length()-i<8 || str.charAt(i+2)!=':' || str.charAt(i+5)!=':' )
            throw new SQLException("Malformed time");

        String hour     = str.substring(i, i+2);
        String minute   = str.substring(i+3, i+3+2);
        String second   = str.substring(i+3+3, i+3+3+2);
        String fraction = "000";
        i = i+8;
        if( str.length()>i && str.charAt(i)=='.' )
        {
            fraction = "";
            i++;
            while( str.length()>i && validDigits(str.substring(i,i+1)) )
                fraction = fraction + str.substring(i,++i);

            if( fraction.length() > 3 )
                fraction = fraction.substring(0,3);
            else
                while( fraction.length()<3 )
                    fraction = fraction + "0";
        }


        // Make sure there isn't any garbage after the time
        i = skipWhitespace(str, i);
        i = skipQuote(str, i);
        i = skipWhitespace(str, i);

        if (i<str.length())
        {
           throw new SQLException("Malformed date");
        }

        return "'" + year + month + day + " "
                + hour + ":" + minute + ":" + second + "." + fraction + "'";
    }

    public String expandEscape(String escapeSequence) throws SQLException
    {
        String str    = new String(escapeSequence);
        String result = null;