resultset.java

来自「J2ME MIDP_Example_Applications」· Java 代码 · 共 367 行

// Copyright 2003 Nokia Corporation.
//
// THIS SOURCE CODE IS PROVIDED 'AS IS', WITH NO WARRANTIES WHATSOEVER,
// EXPRESS OR IMPLIED, INCLUDING ANY WARRANTY OF MERCHANTABILITY, FITNESS
// FOR ANY PARTICULAR PURPOSE, OR ARISING FROM A COURSE OF DEALING, USAGE
// OR TRADE PRACTICE, RELATING TO THE SOURCE CODE OR ANY WARRANTY OTHERWISE
// ARISING OUT OF ANY PROPOSAL, SPECIFICATION, OR SAMPLE AND WITH NO
// OBLIGATION OF NOKIA TO PROVIDE THE LICENSEE WITH ANY MAINTENANCE OR
// SUPPORT. FURTHERMORE, NOKIA MAKES NO WARRANTY THAT EXERCISE OF THE
// RIGHTS GRANTED HEREUNDER DOES NOT INFRINGE OR MAY NOT CAUSE INFRINGEMENT
// OF ANY PATENT OR OTHER INTELLECTUAL PROPERTY RIGHTS OWNED OR CONTROLLED
// BY THIRD PARTIES
//
// Furthermore, information provided in this source code is preliminary,
// and may be changed substantially prior to final release. Nokia Corporation
// retains the right to make changes to this source code at
// any time, without notice. This source code is provided for informational
// purposes only.
//
// Nokia and Nokia Connecting People are registered trademarks of Nokia
// Corporation.
// Java and all Java-based marks are trademarks or registered trademarks of
// Sun Microsystems, Inc.
// Other product and company names mentioned herein may be trademarks or
// trade names of their respective owners.
//
// A non-exclusive, non-transferable, worldwide, limited license is hereby
// granted to the Licensee to download, print, reproduce and modify the
// source code. The licensee has the right to market, sell, distribute and
// make available the source code in original or modified form only when
// incorporated into the programs developed by the Licensee. No other
// license, express or implied, by estoppel or otherwise, to any other
// intellectual property rights is granted herein.
package example.mesql;

import java.util.*;

public class ResultSet
{
  // keeps track of the current row
  private int currentRow = 0;
  private Vector allRows = new Vector();
  private Vector columns = new Vector();
  private Vector columnTypes = new Vector();
  private Statement statement = null;
  private int rowsUpdated = -1;

  ResultSet(String response) throws SQLException
  {
    parseResponse(response);
  }

  // moves to an absolute toe
  public boolean absolute(int row)
  {
    if (row < 0)
    {
      row = allRows.size() - row;
    }
    if (row < 0)
    {
      row = 1;
    }
    if (row > allRows.size())
    {
      row = allRows.size();
    }
    currentRow = row;
    return currentRow > 0 && currentRow <= allRows.size();
  }

  // move to the row after the last
  public void afterLast()
  {
    currentRow = allRows.size() + 1;
  }

  // move to the row before the first one
  public void beforeFirst()
  {
    currentRow = 0;
  }

  // finds a column by name
  public int findColumn(String columnName)
    throws SQLException
  {
    for (int i = 0; i < columns.size(); i++)
    {
      if (columns.elementAt(i).equals(columnName.toLowerCase()))
      {
        return i + 1;
      }
    }
    throw new SQLException(new StringBuffer("Column ")
      .append(columnName).append(" not in this result set")
      .toString());
  }

  // goes to the first row
  public boolean first()
  {
    return absolute(1);
  }

  // checks whether it is after the last row
  public boolean isAfterLast()
  {
    return currentRow == allRows.size() + 1;
  }

  // checks whether it is before the first row
  public boolean isBeforeFirst()
  {
    return currentRow == 0;
  }

  // checks whether it is in the first row
  public boolean isFirst()
  {
    return currentRow == 1;
  }

  // checks whether it is in the kast row
  public boolean isLast()
  {
    return currentRow == allRows.size();
  }

  // goes to the last row
  public boolean last()
  {
    return absolute(-1);
  }

  // goes to the next row
  public boolean next()
  {
    if (currentRow <= allRows.size())
    {
      currentRow++;
    }
    return currentRow <= allRows.size();
  }

  // goes back to the first row
  public boolean previous()
  {
    if (currentRow > 0)
    {
      currentRow--;
    }
    return currentRow > 0;
  }

  // move a relative amount of rows
  public boolean relative(int rows)
  {
    return absolute(currentRow + rows);
  }

  // the following methods return the value of a
  // column based on index or column name
  // there are different methods for different types
  // if the column doesn't exist or the type cannot be
  // converted an exception is thrown
  
  public boolean getBoolean(int columnIndex)
    throws SQLException
  {
    String value = findValue(columnIndex);
    return "true".equals(value) || "TRUE".equals(value);
  }

  public boolean getBoolean(String columnName)
    throws SQLException
  {
    return getBoolean(findColumn(columnName));
  }

  public byte getByte(int columnIndex)
    throws SQLException
  {
    String value = findValue(columnIndex);
    byte result = 0;
    if (value != null && !value.toLowerCase().equals("null"))
    {
      try
      {
        result = Byte.parseByte(value);
      }
      catch (NumberFormatException e)
      {
        throw new SQLException(e.getMessage());
      }
    }
    return result;
  }

  byte getByte(String columnName)
    throws SQLException
  {
    return getByte(findColumn(columnName));
  }

  public int getInt(int columnIndex)
    throws SQLException
  {
    String value = findValue(columnIndex);
    int result = 0;
    if (value != null && !value.toLowerCase().equals("null"))
    {
      try
      {
        result = Integer.parseInt(value);
      }
      catch (NumberFormatException e)
      {
        throw new SQLException(e.getMessage());
      }
    }
    return result;
  }

  public int getInt(String columnName)
    throws SQLException
  {
    return getInt(findColumn(columnName));
  }

  long getLong(int columnIndex)
    throws SQLException
  {
    String value = findValue(columnIndex);
    long result = 0;
    if (value != null && !value.toLowerCase().equals("null"))
    {
      try
      {
        result = Long.parseLong(value);
      }
      catch (NumberFormatException e)
      {
        throw new SQLException(e.getMessage());
      }
    }
    return result;
  }

  long getLong(String columnName)
    throws SQLException
  {
    return getLong(findColumn(columnName));
  }

  public int getRow()
  {
    return currentRow;
  }

  public short getShort(int columnIndex)
    throws SQLException
  {
    String value = findValue(columnIndex);
    short result = 0;
    if (value != null && !value.toLowerCase().equals("null"))
    {
      try
      {
        result = Short.parseShort(value);
      }
      catch (NumberFormatException e)
      {
        throw new SQLException(e.getMessage());
      }
    }
    return result;
  }

  public short getShort(String columnName)
    throws SQLException
  {
    return getShort(findColumn(columnName));
  }

  public String getString(int columnIndex)
    throws SQLException
  {
    return findValue(columnIndex);
  }

  public String getString(String columnName)
    throws SQLException
  {
    return getString(findColumn(columnName));
  }

  // parses the HTTP response from the server
  private void parseResponse(String response)
    throws SQLException
  {
    // first a sanity check
    if (response.startsWith("OK\nSELECT\n"))
    {
      response = response.substring(10);
      // tokenize by lines
      Tokenizer tokenizer = new Tokenizer(response, '\n');
      String line = (String) tokenizer.nextElement();
      if (line == null) {
        throw new SQLException("Malformed query response"); 
      }
      
      // first fill in the column names
      Tokenizer cols = new Tokenizer(line, ',');
      while (cols.hasMoreElements())
      {
        columns.addElement(((String) cols.nextElement()).toLowerCase());
      }
      line = (String) tokenizer.nextElement();
      if (line == null) {
        throw new SQLException("Malformed query response"); 
      }
      // next fill in the column types
      cols = new Tokenizer(line, ',');
      while (cols.hasMoreElements())
      {
        columnTypes.addElement(cols.nextElement());
      }
      while (tokenizer.hasMoreElements())
      {
        line = (String)tokenizer.nextElement();
        // store the rows unparsed
        allRows.addElement(line);
      }
    }
  }


  private String findValue(int columnIndex)
    throws SQLException
  {
    if (currentRow > allRows.size())
    {
      throw new SQLException("Row index too large");
    }
    String line = (String) allRows.elementAt(currentRow - 1);
    Tokenizer tokenizer = new Tokenizer(line, ',');
    int currentCol = 1;
    while (tokenizer.hasMoreElements())
    {
      String token = (String) tokenizer.nextElement();
      if (currentCol == columnIndex)
      {
        if ("%0".equals(token))
        {
          return null;
        }
        return Codec.decode(token);
      }
      currentCol++;
    }
    throw new SQLException("Column index too large");
  }

}