csvscrollablereader.java

一种解析csv文件特别好的方法

/*
 *  CsvJdbc - a JDBC driver for CSV files
 *  Copyright (C) 2001  Jonathan Ackerman
 *  This library is free software; you can redistribute it and/or
 *  modify it under the terms of the GNU Lesser General Public
 *  License as published by the Free Software Foundation; either
 *  version 2.1 of the License, or (at your option) any later version.
 *  This library 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 library; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */
package org.relique.jdbc.csv;

import java.io.BufferedReader;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStreamReader;

import java.sql.SQLException;

import java.util.ArrayList;
import java.util.Vector;


/**
 *This class Class provides facility to navigate on the Result Set.
 *
 * @author     Chetan Gupta
 * @version    $Id: CSVScrollableReader.java,v 1.1 2004/04/09 11:17:13 gupta_chetan Exp $
 */
public class CSVScrollableReader extends CSVReaderAdapter {
  //---------------------------------------------------------------------
  // Traversal/Positioning
  //---------------------------------------------------------------------
  private static final int FIRST_RECORD = 0;
  private ArrayList alRecordNos = null;
  private int recordMappedToNo = FIRST_RECORD - 1;
  private ArrayList alRecordsArray = null;
  private int iRecordNo = 0;
  private int iRecordArrayNo = 0;

  /**
   *Constructor for the CsvReader object
   *
   * @param  fileName       Description of Parameter
   * @exception  Exception  Description of Exception
   * @since
   */
  public CSVScrollableReader(String fileName) throws Exception {
    this(fileName, ',', false, null);
  }

  /**
   * Can be put in adpater apart from the last line
   *
   * Insert the method's description here.
   *
   * Creation date: (6-11-2001 15:02:42)
   *
   * @param  fileName                 java.lang.String
   * @param  separator                char
   * @param  suppressHeaders          boolean
   * @exception  java.lang.Exception  The exception description.
   * @since
   */
  public CSVScrollableReader(
    String fileName, char separator, boolean suppressHeaders, String charset)
    throws java.lang.Exception {

    BufferedReader input = null;
    String buf = null;

    this.separator = separator;
    this.suppressHeaders = suppressHeaders;
    this.fileName = fileName;
    this.charset = charset;

    if (charset != null) {
      input =
        new BufferedReader(
          new InputStreamReader(new FileInputStream(fileName), charset));
    } else {
      input =
        new BufferedReader(
          new InputStreamReader(new FileInputStream(fileName)));
    }

    // input = new BufferedReader(new FileReader(fileName));
    if (this.suppressHeaders) {
      // No column names available. Read first data line and determine number of colums.
      buf = input.readLine();

      String[] data = parseCsvLine(buf);
      columnNames = new String[data.length];

      for (int i = 0; i < data.length; i++) {
        columnNames[i] = "COLUMN" + String.valueOf(i + 1);
      }

      data = null;

      // throw away.
    } else {
      String headerLine = input.readLine();
      columnNames = parseCsvLine(headerLine);
    }

    loopAndFetchData(input, buf);
    fillRecordNoMapping();
    iRecordNo = FIRST_RECORD - 1;
    iRecordArrayNo = FIRST_RECORD - 1;
  }

  /*
   * Can be improved a lot,
   *         a) lazy loading
   *    b) integrate it with loopAndFetchData
   */
  private void fillRecordNoMapping() throws SQLException {
    alRecordNos = new ArrayList();
    iRecordNo = FIRST_RECORD - 1;
    iRecordArrayNo = FIRST_RECORD - 1;

    //Map the records in two step 
    //1) Add the first record
    if (alRecordsArray.size() > 1) {
      alRecordNos.add(0, new Integer(0));
    }

    //2) After next the record No will be the last of previous record and 1 less then next record so, we only add the last record
    //Add rest of the records after checking that its not the last records
    for (
      int i = 1;
        readDataFirstTime() && ((alRecordsArray.size() - 1) > iRecordArrayNo);
        i++) {
      alRecordNos.add(i, new Integer(iRecordArrayNo + 1));
    }
  }

  private boolean readDataFirstTime() throws SQLException {
    columns = new String[columnNames.length];

    String dataLine = null;
    iRecordArrayNo++;

    if (
      (iRecordArrayNo < FIRST_RECORD)
        || (iRecordArrayNo >= alRecordsArray.size())) {
      return false;
    }

    dataLine = (String) alRecordsArray.get(iRecordArrayNo);
    columns = parseCsvLine(dataLine);

    return true;
  }

  /**
   *Description of the Method
   *
   * @return                Description of the Returned Value
   * @exception  SQLException  Description of Exception
   * @since
   */
  private boolean loopAndFetchData(BufferedReader input, String buf)
    throws SQLException {
    alRecordsArray = new ArrayList();

    while (true) {
      columns = new String[columnNames.length];

      String dataLine = null;

      try {
        if (suppressHeaders && (buf != null)) {
          // The buffer is not empty yet, so use this first.
          dataLine = buf;
          buf = null;
        } else {
          // read new line of data from input.
          dataLine = input.readLine();
        }

        if (dataLine == null) {
          input.close();

          return false;
        }
      } catch (IOException e) {
        throw new SQLException(e.toString());
      }

      alRecordsArray.add(dataLine);
    }
  }

  // This code updated with code by Stuart Mottram to handle line breaks in fields
  // see bug #492063
  protected String[] parseCsvLine(String line) throws SQLException {
    Vector values = new Vector();
    boolean inQuotedString = false;
    String value = "";
    String orgLine = line;
    int currentPos = 0;
    int fullLine = 0;

    while (fullLine == 0) {
      currentPos = 0;
      line += separator;

      while (currentPos < line.length()) {
//        System.out.println("=currentPos == " + currentPos);
        char currentChar = line.charAt(currentPos);

        if ((value.length() == 0) && (currentChar == '"') && !inQuotedString) {

//          System.out.println("\n\n\n == ");
//          System.out.println("-currentChar == " + currentChar);
//          System.out.println("-currentPos == " + currentPos);
//          System.out.println("-line == " + line);
//          System.out.println("-inQuotedString == " + inQuotedString);

          currentPos++;
          inQuotedString = true;

          continue;
        }

        if (currentChar == '"') {
          char nextChar = line.charAt(currentPos + 1);

          if (nextChar == '"') {
            value += currentChar;
            currentPos++;
          } else {
            if (!inQuotedString) {
              throw new SQLException(
                "Unexpected '\"' in position " + currentPos + ". Line="
                + orgLine);
            }

            if (inQuotedString && (nextChar != separator)) {
/*          System.out.println("\n\n\n == ");
              System.out.println("currentChar == " + currentChar);
          System.out.println("currentPos == " + currentPos);
          System.out.println("line == " + line);
              System.out.println("nextChar == " + nextChar);
              System.out.println("inQuotedString == " + inQuotedString);
 */
              throw new SQLException(
                "Expecting " + separator + " in position " + (currentPos + 1)
                + ". Line=" + orgLine);
            }

            values.add(value);
            value = "";
            inQuotedString = false;
            currentPos++;
          }
        } else {
          if (currentChar == separator) {
            if (inQuotedString) {
              value += currentChar;
            } else {
              values.add(value);
              value = "";
            }
          } else {
            value += currentChar;
          }
        }

        currentPos++;
      }

      if (inQuotedString) {
        // Remove extra , added at start
        value = value.substring(0, value.length() - 1);

        try {