org.apache.metamodel.excel.ExcelDataContext Maven / Gradle / Ivy
/**
* Licensed to the Apache Software Foundation (ASF) under one
* or more contributor license agreements. See the NOTICE file
* distributed with this work for additional information
* regarding copyright ownership. The ASF licenses this file
* to you under the Apache License, Version 2.0 (the
* "License"); you may not use this file except in compliance
* with the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing,
* software distributed under the License is distributed on an
* "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
* KIND, either express or implied. See the License for the
* specific language governing permissions and limitations
* under the License.
*/
package org.apache.metamodel.excel;
import java.io.File;
import java.io.IOException;
import java.io.InputStream;
import java.io.PushbackInputStream;
import org.apache.poi.POIXMLDocument;
import org.apache.metamodel.DataContext;
import org.apache.metamodel.MetaModelException;
import org.apache.metamodel.QueryPostprocessDataContext;
import org.apache.metamodel.UpdateScript;
import org.apache.metamodel.UpdateableDataContext;
import org.apache.metamodel.data.DataSet;
import org.apache.metamodel.schema.Column;
import org.apache.metamodel.schema.MutableSchema;
import org.apache.metamodel.schema.Schema;
import org.apache.metamodel.schema.Table;
import org.apache.metamodel.util.FileHelper;
import org.apache.metamodel.util.FileResource;
import org.apache.metamodel.util.LazyRef;
import org.apache.metamodel.util.Ref;
import org.apache.metamodel.util.Resource;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
/**
* {@link DataContext} implementation to use for Excel spreadsheets.
*
* This DataContext supports both the "old" .xls format and the "new" .xlsx
* format, and saves the user the trouble of figuring out which one to use,
* simply by detecting it at runtime and delegating to the appropriate
* implementation.
*/
public final class ExcelDataContext extends QueryPostprocessDataContext implements UpdateableDataContext {
private static final Logger logger = LoggerFactory.getLogger(ExcelDataContext.class);
private final Object WRITE_LOCK = new Object();
private final Resource _resource;
private final ExcelConfiguration _configuration;
private SpreadsheetReaderDelegate _spreadsheetReaderDelegate;
/**
* Constructs an Excel DataContext based on a file, with default
* configuration
*
* @param file
*/
public ExcelDataContext(File file) {
this(file, new ExcelConfiguration());
}
/**
* Constructs an Excel DataContext based on a resource and a custom
* configuration.
*
* The file provided can be either existing or non-existing. In the
* case of non-existing files, a file will be automatically created
* when a CREATE TABLE update is executed on the DataContext.
*
* @param file
* @param configuration
*/
public ExcelDataContext(File file, ExcelConfiguration configuration) {
if (file == null) {
throw new IllegalArgumentException("File cannot be null");
}
if (configuration == null) {
throw new IllegalArgumentException("ExcelConfiguration cannot be null");
}
if (file.exists() && !file.canRead()) {
throw new IllegalArgumentException("Cannot read from file");
}
_resource = new FileResource(file);
_configuration = configuration;
}
public ExcelDataContext(Resource resource, ExcelConfiguration configuration) {
if (resource == null) {
throw new IllegalArgumentException("Resource cannot be null");
}
if (configuration == null) {
throw new IllegalArgumentException("ExcelConfiguration cannot be null");
}
_resource = resource;
_configuration = configuration;
}
/**
* Gets the Excel configuration used.
*
* @return an excel configuration.
*/
public ExcelConfiguration getConfiguration() {
return _configuration;
}
/**
* Gets the Excel file being read.
*
* @return a file.
* @deprecated
*/
@Deprecated
public File getFile() {
if (_resource instanceof FileResource) {
return ((FileResource) _resource).getFile();
}
return null;
}
/**
* Gets the Excel resource being read
*
* @return
*/
public Resource getResource() {
return _resource;
}
@Override
protected String getMainSchemaName() throws MetaModelException {
return _resource.getName();
}
@Override
public DataSet materializeMainSchemaTable(Table table, Column[] columns, int maxRows) {
Ref inputStreamRef = getInputStreamRef();
InputStream inputStream = null;
try {
SpreadsheetReaderDelegate delegate = getSpreadsheetReaderDelegate(inputStreamRef);
inputStream = inputStreamRef.get();
// METAMODEL-47: Ensure that we have loaded the schema at this point
getDefaultSchema();
DataSet dataSet = delegate.executeQuery(inputStream, table, columns, maxRows);
return dataSet;
} catch (Exception e) {
if (e instanceof RuntimeException) {
throw (RuntimeException) e;
}
throw new MetaModelException("Unexpected exception while materializing main schema table", e);
} finally {
FileHelper.safeClose(inputStream);
}
}
@Override
protected Schema getMainSchema() throws MetaModelException {
if (!_resource.isExists()) {
logger.info("Resource does not exist, returning empty schema");
return new MutableSchema(getMainSchemaName());
}
Ref inputStreamRef = getInputStreamRef();
InputStream inputStream = null;
try {
SpreadsheetReaderDelegate delegate = getSpreadsheetReaderDelegate(inputStreamRef);
inputStream = inputStreamRef.get();
Schema schema = delegate.createSchema(inputStream, getMainSchemaName());
assert getMainSchemaName().equals(schema.getName());
return schema;
} catch (Exception e) {
if (e instanceof RuntimeException) {
throw (RuntimeException) e;
}
throw new MetaModelException("Unexpected exception while building main schema", e);
} finally {
FileHelper.safeClose(inputStream);
}
}
/**
* Convenient method for testing and inspecting internal state.
*
* @return the class of the spreadsheet reader delegate.
*/
protected Class getSpreadsheetReaderDelegateClass() {
if (_spreadsheetReaderDelegate != null) {
return _spreadsheetReaderDelegate.getClass();
}
return null;
}
private SpreadsheetReaderDelegate getSpreadsheetReaderDelegate(Ref inputStream) throws MetaModelException {
if (_spreadsheetReaderDelegate == null) {
synchronized (this) {
if (_spreadsheetReaderDelegate == null) {
try {
if (POIXMLDocument.hasOOXMLHeader(inputStream.get())) {
_spreadsheetReaderDelegate = new XlsxSpreadsheetReaderDelegate(_configuration);
} else {
_spreadsheetReaderDelegate = new DefaultSpreadsheetReaderDelegate(_configuration);
}
} catch (IOException e) {
logger.error("Could not identify spreadsheet type, using default", e);
_spreadsheetReaderDelegate = new DefaultSpreadsheetReaderDelegate(_configuration);
}
}
}
}
return _spreadsheetReaderDelegate;
}
private InputStream getInputStream() throws MetaModelException {
InputStream inputStream = _resource.read();
if (!inputStream.markSupported()) {
inputStream = new PushbackInputStream(inputStream, 8);
}
return inputStream;
}
private LazyRef getInputStreamRef() throws MetaModelException {
final LazyRef inputStreamRef = new LazyRef() {
@Override
public InputStream fetch() {
InputStream inputStream = getInputStream();
return inputStream;
}
};
return inputStreamRef;
}
protected void notifyTablesModified() {
LazyRef inputStreamRef = getInputStreamRef();
try {
getSpreadsheetReaderDelegate(inputStreamRef).notifyTablesModified(inputStreamRef);
} finally {
if (inputStreamRef.isFetched()) {
FileHelper.safeClose(inputStreamRef.get());
}
}
}
@Override
public void executeUpdate(UpdateScript update) {
ExcelUpdateCallback updateCallback = new ExcelUpdateCallback(this);
synchronized (WRITE_LOCK) {
try {
update.run(updateCallback);
} finally {
updateCallback.close();
}
}
}
}