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A module for Apache MetaModel to read MS Access (.mdb and .accdb) database files
/**
* 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.access;
import java.io.File;
import java.io.IOException;
import java.util.Iterator;
import java.util.LinkedList;
import java.util.List;
import java.util.stream.Collectors;
import org.apache.metamodel.MetaModelException;
import org.apache.metamodel.QueryPostprocessDataContext;
import org.apache.metamodel.data.CachingDataSetHeader;
import org.apache.metamodel.data.DataSet;
import org.apache.metamodel.data.DataSetHeader;
import org.apache.metamodel.data.DefaultRow;
import org.apache.metamodel.data.InMemoryDataSet;
import org.apache.metamodel.data.Row;
import org.apache.metamodel.query.FilterItem;
import org.apache.metamodel.query.SelectItem;
import org.apache.metamodel.schema.Column;
import org.apache.metamodel.schema.ColumnType;
import org.apache.metamodel.schema.ColumnTypeImpl;
import org.apache.metamodel.schema.MutableColumn;
import org.apache.metamodel.schema.MutableSchema;
import org.apache.metamodel.schema.MutableTable;
import org.apache.metamodel.schema.Schema;
import org.apache.metamodel.schema.Table;
import org.apache.metamodel.schema.TableType;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
import com.healthmarketscience.jackcess.Database;
import com.healthmarketscience.jackcess.DatabaseBuilder;
import com.healthmarketscience.jackcess.Index;
/**
* DataContext implementation for MS Access database files.
*/
public final class AccessDataContext extends QueryPostprocessDataContext {
private static final Logger logger = LoggerFactory.getLogger(AccessDataContext.class);
private final File _file;
private Database _database;
public AccessDataContext(String filename) {
this(new File(filename));
}
public AccessDataContext(File file) {
super(false);
_file = file;
}
private Database getDatabase() {
if (_database == null) {
synchronized (this) {
if (_database == null) {
try {
_database = new DatabaseBuilder(_file).setReadOnly(true).open();
} catch (IOException e) {
throw new MetaModelException(e);
}
}
}
}
return _database;
}
@Override
protected Schema getMainSchema() throws MetaModelException {
MutableSchema schema = new MutableSchema(_file.getName());
Database db = getDatabase();
for (com.healthmarketscience.jackcess.Table mdbTable : db) {
final MutableTable table = new MutableTable(mdbTable.getName(), TableType.TABLE, schema);
try {
int i = 0;
for (com.healthmarketscience.jackcess.Column mdbColumn : mdbTable.getColumns()) {
final ColumnType columnType = ColumnTypeImpl.convertColumnType(mdbColumn.getSQLType());
final MutableColumn column = new MutableColumn(mdbColumn.getName(), columnType, table, i, null);
column.setColumnSize((int) mdbColumn.getLength());
column.setNativeType(mdbColumn.getType().name());
table.addColumn(column);
i++;
}
try {
final Index primaryKeyIndex = mdbTable.getPrimaryKeyIndex();
final List columnDescriptors = primaryKeyIndex
.getColumns();
for (com.healthmarketscience.jackcess.Index.Column columnDescriptor : columnDescriptors) {
final String name = columnDescriptor.getName();
final MutableColumn column = (MutableColumn) table.getColumnByName(name);
if (column != null) {
column.setPrimaryKey(true);
}
}
} catch (Exception e) {
logger.warn("Failed to get PK index info for table: {}", mdbTable, e);
}
schema.addTable(table);
} catch (Exception e) {
throw new MetaModelException(e);
}
}
return schema;
}
@Override
protected String getMainSchemaName() throws MetaModelException {
return _file.getName();
}
@Override
protected Number executeCountQuery(Table table, List whereItems, boolean functionApproximationAllowed) {
try {
com.healthmarketscience.jackcess.Table mdbTable = getDatabase().getTable(table.getName());
return mdbTable.getRowCount();
} catch (Exception e) {
throw new MetaModelException(e);
}
}
@Override
public DataSet materializeMainSchemaTable(Table table, List columns, int maxRows) {
try {
final com.healthmarketscience.jackcess.Table mdbTable = getDatabase().getTable(table.getName());
final List selectItems = columns.stream().map(c -> new SelectItem(c)).collect(Collectors.toList());
final DataSetHeader header = new CachingDataSetHeader(selectItems);
int rowNum = 0;
final List data = new LinkedList();
final Iterator it = mdbTable.iterator();
while (it.hasNext() && (maxRows < 0 || rowNum < maxRows)) {
rowNum++;
final com.healthmarketscience.jackcess.Row valueMap = it.next();
final Object[] values = new Object[columns.size()];
for (int j = 0; j < columns.size(); j++) {
values[j] = valueMap.get(columns.get(j).getName());
}
data.add(new DefaultRow(header, values));
}
return new InMemoryDataSet(header, data);
} catch (Exception e) {
throw new MetaModelException(e);
}
}
public File getFile() {
return _file;
}
@Override
protected void finalize() throws Throwable {
super.finalize();
_database.close();
}
}