quiz.CsvLoader.java Source code

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Here is the source code for quiz.CsvLoader.java

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/*
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 */
package quiz;

/**
 *
 * @author henrykmg
 */
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.sql.Connection;
import java.sql.PreparedStatement;
import java.util.Date;

//import org.apache.commons.lang.StringUtils;

import com.opencsv.CSVReader;
import com.sun.xml.wss.util.DateUtils;
import org.apache.commons.lang.StringUtils;

/**
 * 
 * @author viralpatel.net
 * 
 */
public class CsvLoader {

    private static final String SQL_INSERT = "INSERT INTO ${table}(${keys}) VALUES(${values})";
    private static final String TABLE_REGEX = "\\$\\{table\\}";
    private static final String KEYS_REGEX = "\\$\\{keys\\}";
    private static final String VALUES_REGEX = "\\$\\{values\\}";

    private Connection connection;
    private char seprator;

    /**
     * Public constructor to build CSVLoader object with
     * Connection details. The connection is closed on success
     * or failure.
     * @param connection
     */
    public CsvLoader(Connection connection) {
        this.connection = connection;
        //Set default separator
        this.seprator = ',';
    }

    /**
     * Parse CSV file using OpenCSV library and load in 
     * given database table. 
     * @param csvFile Input CSV file
     * @param tableName Database table name to import data
     * @param truncateBeforeLoad Truncate the table before inserting 
     *          new records.
     * @throws Exception
     */
    public void loadCSV(String csvFile, String tableName, boolean truncateBeforeLoad) throws Exception {

        CSVReader csvReader = null;
        if (null == this.connection) {
            throw new Exception("Not a valid connection.");
        }
        try {

            csvReader = new CSVReader(new FileReader(csvFile), this.seprator);

        } catch (Exception e) {
            e.printStackTrace();
            throw new Exception("Error occured while executing file. " + e.getMessage());
        }

        String[] headerRow = csvReader.readNext();

        if (null == headerRow) {
            throw new FileNotFoundException(
                    "No columns defined in given CSV file." + "Please check the CSV file format.");
        }

        String questionmarks = StringUtils.repeat("?,", headerRow.length);
        questionmarks = (String) questionmarks.subSequence(0, questionmarks.length() - 1);

        String query = SQL_INSERT.replaceFirst(TABLE_REGEX, tableName);
        query = query.replaceFirst(KEYS_REGEX, StringUtils.join(headerRow, ","));
        query = query.replaceFirst(VALUES_REGEX, questionmarks);

        System.out.println("Query: " + query);

        String[] nextLine;
        Connection con = null;
        PreparedStatement ps = null;
        try {
            con = this.connection;
            con.setAutoCommit(false);
            ps = con.prepareStatement(query);

            if (truncateBeforeLoad) {
                //delete data from table before loading csv
                con.createStatement().execute("DELETE FROM " + tableName);
            }

            final int batchSize = 1000;
            int count = 0;
            Date date = null;
            while ((nextLine = csvReader.readNext()) != null) {

                if (null != nextLine) {
                    int index = 1;
                    for (String string : nextLine) {

                        date = DateUtils.stringToDate(string);
                        if (null != date) {
                            ps.setDate(index++, new java.sql.Date(date.getTime()));
                        } else {
                            ps.setString(index++, string);
                        }
                    }
                    ps.addBatch();
                }
                if (++count % batchSize == 0) {
                    ps.executeBatch();
                }
            }
            ps.executeBatch(); // insert remaining records
            con.commit();
        } catch (Exception e) {
            con.rollback();
            e.printStackTrace();
            throw new Exception("Error occured while loading data from file to database." + e.getMessage());
        } finally {
            if (null != ps)
                ps.close();
            if (null != con)
                con.close();

            csvReader.close();
        }
    }

    public char getSeprator() {
        return seprator;
    }

    public void setSeprator(char seprator) {
        this.seprator = seprator;
    }

}