org.eobjects.metamodel.dbase.DbaseDataContext Maven / Gradle / Ivy

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/**
 * eobjects.org MetaModel
 * Copyright (C) 2010 eobjects.org
 *
 * This copyrighted material is made available to anyone wishing to use, modify,
 * copy, or redistribute it subject to the terms and conditions of the GNU
 * Lesser General Public License, as published by the Free Software Foundation.
 *
 * 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 Lesser General Public License
 * for more details.
 *
 * You should have received a copy of the GNU Lesser General Public License
 * along with this distribution; if not, write to:
 * Free Software Foundation, Inc.
 * 51 Franklin Street, Fifth Floor
 * Boston, MA  02110-1301  USA
 */

package org.eobjects.metamodel.dbase;

import java.io.Closeable;
import java.io.File;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.Date;
import java.util.LinkedList;
import java.util.List;

import org.eobjects.metamodel.MetaModelException;
import org.eobjects.metamodel.MetaModelHelper;
import org.eobjects.metamodel.QueryPostprocessDataContext;
import org.eobjects.metamodel.data.DataSet;
import org.eobjects.metamodel.data.DefaultRow;
import org.eobjects.metamodel.data.InMemoryDataSet;
import org.eobjects.metamodel.data.Row;
import org.eobjects.metamodel.query.SelectItem;
import org.eobjects.metamodel.schema.Column;
import org.eobjects.metamodel.schema.ColumnType;
import org.eobjects.metamodel.schema.MutableColumn;
import org.eobjects.metamodel.schema.MutableSchema;
import org.eobjects.metamodel.schema.MutableTable;
import org.eobjects.metamodel.schema.Schema;
import org.eobjects.metamodel.schema.Table;
import org.eobjects.metamodel.schema.TableType;
import org.eobjects.metamodel.util.FileHelper;
import org.xBaseJ.DBF;
import org.xBaseJ.fields.CharField;
import org.xBaseJ.fields.DateField;
import org.xBaseJ.fields.Field;
import org.xBaseJ.fields.FloatField;
import org.xBaseJ.fields.LogicalField;
import org.xBaseJ.fields.MemoField;
import org.xBaseJ.fields.NumField;
import org.xBaseJ.fields.PictureField;

/**
 * DataContext implementation for dBase database files.
 * 
 * @author Kasper Sørensen
 */
public final class DbaseDataContext extends QueryPostprocessDataContext
		implements Closeable {

	private final String filename;
	private DBF dbf;

	public DbaseDataContext(String filename) {
		this.filename = filename;
	}

	public DbaseDataContext(File file) {
		this.filename = file.getAbsolutePath();
	}

	private DBF getDbf() {
		if (dbf == null) {
			synchronized (this) {
				if (dbf == null) {
					try {
						dbf = new DBF(filename);
					} catch (Exception e) {
						throw new MetaModelException("Could not open DBF file");
					}
				}
			}
		}
		return dbf;
	}

	@Override
	protected Schema getMainSchema() throws MetaModelException {
		DBF dbf = getDbf();

		String schemaName = dbf.getName();
		int separatorIndex = Math.max(schemaName.lastIndexOf('/'),
				schemaName.lastIndexOf('\\'));
		if (separatorIndex != -1) {
			schemaName = schemaName.substring(separatorIndex + 1);
		}

		MutableSchema schema = new MutableSchema(schemaName);
		MutableTable table = new MutableTable(schemaName.substring(0,
				schemaName.length() - 4), TableType.TABLE, schema);
		schema.addTable(table);

		for (int i = 0; i < dbf.getFieldCount(); i++) {
			try {
				Field field = dbf.getField(i + 1);

				MutableColumn column = new MutableColumn(field.getName());
				ColumnType columnType = ColumnType.VARCHAR;

				if (field instanceof FloatField) {
					columnType = ColumnType.FLOAT;
				} else if (field instanceof NumField) {
					columnType = ColumnType.DOUBLE;
				} else if (field instanceof CharField) {
					columnType = ColumnType.CHAR;
				} else if (field instanceof DateField) {
					columnType = ColumnType.DATE;
				} else if (field instanceof MemoField) {
					columnType = ColumnType.VARCHAR;
				} else if (field instanceof LogicalField) {
					columnType = ColumnType.OTHER;
				} else if (field instanceof PictureField) {
					columnType = ColumnType.OTHER;
				}

				column.setType(columnType);
				column.setTable(table);
				column.setColumnNumber(i);
				column.setNativeType("" + field.getType());
				column.setColumnSize(field.getLength());
				table.addColumn(column);
			} catch (Exception e) {
				throw new MetaModelException("Could not retrieve DBF field", e);
			}
		}

		return schema;
	}

	@Override
	protected String getMainSchemaName() throws MetaModelException {
		return getMainSchema().getName();
	}

	@Override
	public DataSet materializeMainSchemaTable(Table table, Column[] columns,
			int maxRows) {
		DBF dbf = getDbf();
		synchronized (dbf) {
			int rowNum = 0;
			try {
				dbf.gotoRecord(1);
			} catch (Exception e) {
				throw new MetaModelException(e);
			}

			final SelectItem[] selectItems = MetaModelHelper
					.createSelectItems(columns);

			final List rowValues = new LinkedList();
			while (maxRows < 0 || rowNum < maxRows) {
				rowNum++;
				try {
					Object[] values = new Object[columns.length];
					for (int i = 0; i < columns.length; i++) {
						int fieldNumber = 1 + columns[i].getColumnNumber();
						Field field = dbf.getField(fieldNumber);
						values[i] = convert(field.get(), columns[i].getType());
					}
					rowValues.add(new DefaultRow(selectItems, values));
				} catch (Exception e) {
					throw new MetaModelException(e);
				}

				try {
					dbf.read();
				} catch (Exception e) {
					// this exception is thrown if all records have been read
					if ("End Of File".equals(e.getMessage())) {
						break;
					}
					throw new MetaModelException(e);
				}
			}
			return new InMemoryDataSet(rowValues);
		}
	}

	private Object convert(String stringValue, ColumnType type) {
		if (stringValue == null || stringValue.length() == 0) {
			return null;
		}
		switch (type) {
		case FLOAT:
			return Float.parseFloat(stringValue);
		case DOUBLE:
			return Double.parseDouble(stringValue);
		case DATE:
			try {
				Date date = new SimpleDateFormat("yyyyMMdd").parse(stringValue);
				return date;
			} catch (ParseException e) {
				throw new IllegalArgumentException(stringValue);
			}
		default:
			return stringValue;
		}
	}

	@Override
	protected void finalize() throws Throwable {
		super.finalize();
		close();
	}

	@Override
	public void close() {
		FileHelper.safeClose(dbf);
	}
}