boolean success = false;
try {
channel.truncate(0);
- transferFrom(channel, getResourceAsStream(details.getEmptyFilePath()));
+ transferDbFrom(channel, getResourceAsStream(details.getEmptyFilePath()));
channel.force(true);
DatabaseImpl db = new DatabaseImpl(mdbFile, channel, closeChannel, autoSync,
- fileFormat, charset, timeZone, null);
+ fileFormat, charset, timeZone, null);
success = true;
return db;
} finally {
* @param timeZone TimeZone to use, if {@code null}, uses default
*/
protected DatabaseImpl(File file, FileChannel channel, boolean closeChannel,
- boolean autoSync, FileFormat fileFormat, Charset charset,
- TimeZone timeZone, CodecProvider provider)
+ boolean autoSync, FileFormat fileFormat, Charset charset,
+ TimeZone timeZone, CodecProvider provider)
throws IOException
{
_file = file;
* @param includeSystemTables whether to consider returning a system table
* @return The table, or null if it doesn't exist
*/
- private TableImpl getTable(String name, boolean includeSystemTables)
+ protected TableImpl getTable(String name, boolean includeSystemTables)
throws IOException
{
TableInfo tableInfo = getTableInfo(name, includeSystemTables);
}
/**
- * Copies the given InputStream to the given channel using the most
+ * Copies the given db InputStream to the given channel using the most
* efficient means possible.
*/
- static void transferFrom(FileChannel channel, InputStream in)
+ protected static void transferDbFrom(FileChannel channel, InputStream in)
throws IOException
{
ReadableByteChannel readChannel = Channels.newChannel(in);
return pwdMask;
}
- static InputStream getResourceAsStream(String resourceName)
+ protected static InputStream getResourceAsStream(String resourceName)
throws IOException
{
InputStream stream = DatabaseImpl.class.getClassLoader()
--- /dev/null
+/*
+Copyright (c) 2017 James Ahlborn
+
+Licensed 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 com.healthmarketscience.jackcess.util;
+
+import java.io.Closeable;
+import java.io.File;
+import java.io.IOException;
+import java.io.RandomAccessFile;
+import java.nio.channels.FileChannel;
+import java.util.Random;
+
+import com.healthmarketscience.jackcess.Database;
+import com.healthmarketscience.jackcess.Database.FileFormat;
+import com.healthmarketscience.jackcess.Table;
+import com.healthmarketscience.jackcess.impl.ByteUtil;
+import com.healthmarketscience.jackcess.impl.DatabaseImpl;
+import com.healthmarketscience.jackcess.impl.TableImpl;
+
+/**
+ * Utility base implementaton of LinkResolver which facilitates loading linked
+ * tables from files which are not access databases. The LinkResolver API
+ * ultimately presents linked table information to the primary database using
+ * the jackcess {@link Database} and {@link Table} classes. In order to
+ * consume linked tables in non-mdb files, they need to somehow be coerced
+ * into the appropriate form. The approach taken by this utility is to make
+ * it easy to copy the external tables into a temporary mdb file for
+ * consumption by the primary database.
+ * <p>
+ * The primary features of this utility:
+ * <ul>
+ * <li>Supports custom behavior for non-mdb files and default behavior for mdb
+ * files, see {@link #loadCustomFile}</li>
+ * <li>Temp db can be an actual file or entirely in memory</li>
+ * <li>Linked tables are loaded on-demand, see {@link #loadCustomTable}</li>
+ * <li>Temp db files will be automatically deleted on close</li>
+ * </ul>
+ *
+ * @author James Ahlborn
+ * @usage _intermediate_class_
+ */
+public abstract class CustomLinkResolver implements LinkResolver
+{
+ private static final Random DB_ID = new Random();
+
+ private static final String MEM_DB_PREFIX = "memdb_";
+ private static final String FILE_DB_PREFIX = "linkeddb_";
+
+ /** the default file format used for temp dbs */
+ public static final FileFormat DEFAULT_FORMAT = FileFormat.V2000;
+ /** temp dbs default to the filesystem, not in memory */
+ public static final boolean DEFAULT_IN_MEMORY = false;
+ /** temp dbs end up in the system temp dir by default */
+ public static final File DEFAULT_TEMP_DIR = null;
+
+ private final FileFormat _defaultFormat;
+ private final boolean _defaultInMemory;
+ private final File _defaultTempDir;
+
+ /**
+ * Creates a CustomLinkResolver using the default behavior for creating temp
+ * dbs, see {@link #DEFAULT_FORMAT}, {@link #DEFAULT_IN_MEMORY} and
+ * {@link #DEFAULT_TEMP_DIR}.
+ */
+ protected CustomLinkResolver() {
+ this(DEFAULT_FORMAT, DEFAULT_IN_MEMORY, DEFAULT_TEMP_DIR);
+ }
+
+ /**
+ * Creates a CustomLinkResolver with the given default behavior for creating
+ * temp dbs.
+ *
+ * @param defaultFormat the default format for the temp db
+ * @param defaultInMemory whether or not the temp db should be entirely in
+ * memory by default (while this will be faster, it
+ * should only be used if table data is expected to
+ * fit entirely in memory)
+ * @param defaultTempDir the default temp dir for a file based temp db
+ * ({@code null} for the system defaqult temp
+ * directory)
+ */
+ protected CustomLinkResolver(FileFormat defaultFormat, boolean defaultInMemory,
+ File defaultTempDir)
+ {
+ _defaultFormat = defaultFormat;
+ _defaultInMemory = defaultInMemory;
+ _defaultTempDir = defaultTempDir;
+ }
+
+ /**
+ * Custom implementation is:
+ * <pre>
+ * // attempt to load the linkeeFileName as a custom file
+ * Object customFile = loadCustomFile(linkerDb, linkeeFileName);
+ *
+ * if(customFile != null) {
+ * // this is a custom file, create and return relevant temp db
+ * return createTempDb(customFile, _defaultFormat, _defaultInMemory,
+ * _defaultTempDir);
+ * }
+ *
+ * // not a custmom file, load using the default behavior
+ * return LinkResolver.DEFAULT.resolveLinkedDatabase(linkerDb, linkeeFileName);
+ * </pre>
+ *
+ * @see #loadCustomFile
+ * @see #createTempDb
+ * @see LinkResolver#DEFAULT
+ */
+ public Database resolveLinkedDatabase(Database linkerDb, String linkeeFileName)
+ throws IOException
+ {
+ Object customFile = loadCustomFile(linkerDb, linkeeFileName);
+ if(customFile != null) {
+ return createTempDb(customFile, _defaultFormat, _defaultInMemory,
+ _defaultTempDir);
+ }
+ return LinkResolver.DEFAULT.resolveLinkedDatabase(linkerDb, linkeeFileName);
+ }
+
+ /**
+ * Creates a temporary database for holding the table data from
+ * linkeeFileName.
+ *
+ * @param customFile custom file state returned from {@link #loadCustomFile}
+ * @param format the access format for the temp db
+ * @param inMemory whether or not the temp db should be entirely in memory
+ * (while this will be faster, it should only be used if
+ * table data is expected to fit entirely in memory)
+ * @param tempDir the temp dir for a file based temp db ({@code null} for
+ * the system default temp directory)
+ *
+ * @return the temp db for holding the linked table info
+ */
+ protected Database createTempDb(Object customFile, FileFormat format,
+ boolean inMemory, File tempDir)
+ throws IOException
+ {
+ File dbFile = null;
+ FileChannel channel = null;
+ boolean success = false;
+ try {
+
+ if(inMemory) {
+ dbFile = new File(MEM_DB_PREFIX + DB_ID.nextLong() +
+ format.getFileExtension());
+ channel = MemFileChannel.newChannel();
+ } else {
+ dbFile = File.createTempFile(FILE_DB_PREFIX, format.getFileExtension(),
+ tempDir);
+ channel = new RandomAccessFile(dbFile, DatabaseImpl.RW_CHANNEL_MODE)
+ .getChannel();
+ }
+
+ TempDatabaseImpl.initDbChannel(channel, format);
+ TempDatabaseImpl db = new TempDatabaseImpl(this, customFile, dbFile,
+ channel, format);
+ success = true;
+ return db;
+
+ } finally {
+ if(!success) {
+ ByteUtil.closeQuietly(channel);
+ deleteDbFile(dbFile);
+ closeCustomFile(customFile);
+ }
+ }
+ }
+
+ private static void deleteDbFile(File dbFile) {
+ if((dbFile != null) && (dbFile.getName().startsWith(FILE_DB_PREFIX))) {
+ dbFile.delete();
+ }
+ }
+
+ private static void closeCustomFile(Object customFile) {
+ if(customFile instanceof Closeable) {
+ ByteUtil.closeQuietly((Closeable)customFile);
+ }
+ }
+
+ /**
+ * Called by {@link #resolveLinkedDatabase} to determine whether the
+ * linkeeFileName should be treated as a custom file (thus utiliziing a temp
+ * db) or a normal access db (loaded via the default behavior). Loads any
+ * state necessary for subsequently loading data from linkeeFileName.
+ * <p>
+ * The returned custom file state object will be maintained with the temp db
+ * and passed to {@link #loadCustomTable} whenever a new table needs to be
+ * loaded. Also, if this object is {@link Closeable}, it will be closed
+ * with the temp db.
+ *
+ * @param linkerDb the primary database in which the link is defined
+ * @param linkeeFileName the name of the linked file
+ *
+ * @return non-{@code null} if linkeeFileName should be treated as a custom
+ * file (using a temp db) or {@code null} if it should be treated as
+ * a normal access db.
+ */
+ protected abstract Object loadCustomFile(
+ Database linkerDb, String linkeeFileName) throws IOException;
+
+ /**
+ * Called by an instance of a temp db when a missing table is first requested.
+ *
+ * @param tempDb the temp db instance which should be populated with the
+ * relevant table info for the given tableName
+ * @param customFile custom file state returned from {@link #loadCustomFile}
+ * @param tableName the name of the table which is requested from the linked
+ * file
+ *
+ * @return {@code true} if the table was available in the linked file,
+ * {@code false} otherwise
+ */
+ protected abstract boolean loadCustomTable(
+ Database tempDb, Object customFile, String tableName)
+ throws IOException;
+
+
+ /**
+ * Subclass of DatabaseImpl which allows us to load tables "on demand" as
+ * well as delete the temporary db on close.
+ */
+ private static class TempDatabaseImpl extends DatabaseImpl
+ {
+ private final CustomLinkResolver _resolver;
+ private final Object _customFile;
+
+ protected TempDatabaseImpl(CustomLinkResolver resolver, Object customFile,
+ File file, FileChannel channel,
+ FileFormat fileFormat)
+ throws IOException
+ {
+ super(file, channel, true, false, fileFormat, null, null, null);
+ _resolver = resolver;
+ _customFile = customFile;
+ }
+
+ @Override
+ protected TableImpl getTable(String name, boolean includeSystemTables)
+ throws IOException
+ {
+ TableImpl table = super.getTable(name, includeSystemTables);
+ if((table == null) &&
+ _resolver.loadCustomTable(this, _customFile, name)) {
+ table = super.getTable(name, includeSystemTables);
+ }
+ return table;
+ }
+
+ @Override
+ public void close() throws IOException {
+ try {
+ super.close();
+ } finally {
+ deleteDbFile(getFile());
+ closeCustomFile(_customFile);
+ }
+ }
+
+ static FileChannel initDbChannel(FileChannel channel, FileFormat format)
+ throws IOException
+ {
+ FileFormatDetails details = getFileFormatDetails(format);
+ transferDbFrom(channel, getResourceAsStream(details.getEmptyFilePath()));
+ return channel;
+ }
+ }
+
+}
--- /dev/null
+/*
+Copyright (c) 2017 James Ahlborn
+
+Licensed 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 com.healthmarketscience.jackcess.util;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.IOException;
+
+import com.healthmarketscience.jackcess.ColumnBuilder;
+import com.healthmarketscience.jackcess.DataType;
+import com.healthmarketscience.jackcess.Database;
+import com.healthmarketscience.jackcess.Database.FileFormat;
+import com.healthmarketscience.jackcess.Table;
+import com.healthmarketscience.jackcess.TableBuilder;
+import junit.framework.TestCase;
+import static com.healthmarketscience.jackcess.TestUtil.*;
+import static com.healthmarketscience.jackcess.impl.JetFormatTest.*;
+
+/**
+ *
+ * @author James Ahlborn
+ */
+public class CustomLinkResolverTest extends TestCase
+{
+
+ public CustomLinkResolverTest(String name) {
+ super(name);
+ }
+
+ public void testCustomLinkResolver() throws Exception {
+ for(final FileFormat fileFormat : SUPPORTED_FILEFORMATS) {
+ Database db = create(fileFormat);
+
+ db.setLinkResolver(new TestLinkResolver());
+
+ db.createLinkedTable("Table1", "testFile1.txt", "Table1");
+ db.createLinkedTable("Table2", "testFile2.txt", "OtherTable2");
+ db.createLinkedTable("Table3", "missingFile3.txt", "MissingTable3");
+ db.createLinkedTable("Table4", "testFile2.txt", "MissingTable4");
+
+ Table t1 = db.getTable("Table1");
+ assertNotNull(t1);
+ assertNotSame(db, t1.getDatabase());
+
+ assertTable(createExpectedTable(createExpectedRow("id", 0,
+ "data1", "row0"),
+ createExpectedRow("id", 1,
+ "data1", "row1"),
+ createExpectedRow("id", 2,
+ "data1", "row2")),
+ t1);
+
+ Table t2 = db.getTable("Table2");
+ assertNotNull(t2);
+ assertNotSame(db, t2.getDatabase());
+
+ assertTable(createExpectedTable(createExpectedRow("id", 3,
+ "data2", "row3"),
+ createExpectedRow("id", 4,
+ "data2", "row4"),
+ createExpectedRow("id", 5,
+ "data2", "row5")),
+ t2);
+
+ assertNull(db.getTable("Table4"));
+
+ try {
+ db.getTable("Table3");
+ fail("FileNotFoundException should have been thrown");
+ } catch(FileNotFoundException e) {
+ // success
+ }
+
+ db.close();
+ }
+ }
+
+ private static class TestLinkResolver extends CustomLinkResolver
+ {
+ private TestLinkResolver()
+ {
+ super(DEFAULT_FORMAT, true, DEFAULT_TEMP_DIR);
+ }
+
+ @Override
+ protected Object loadCustomFile(
+ Database linkerDb, String linkeeFileName) throws IOException
+ {
+ return (("testFile1.txt".equals(linkeeFileName) ||
+ "testFile2.txt".equals(linkeeFileName)) ?
+ linkeeFileName : null);
+ }
+
+ @Override
+ protected boolean loadCustomTable(
+ Database tempDb, Object customFile, String tableName)
+ throws IOException
+ {
+ if("Table1".equals(tableName)) {
+
+ assertEquals("testFile1.txt", customFile);
+ Table t = new TableBuilder(tableName)
+ .addColumn(new ColumnBuilder("id", DataType.LONG))
+ .addColumn(new ColumnBuilder("data1", DataType.TEXT))
+ .toTable(tempDb);
+
+ for(int i = 0; i < 3; ++i) {
+ t.addRow(i, "row" + i);
+ }
+
+ return true;
+
+ } else if("OtherTable2".equals(tableName)) {
+
+ assertEquals("testFile2.txt", customFile);
+ Table t = new TableBuilder(tableName)
+ .addColumn(new ColumnBuilder("id", DataType.LONG))
+ .addColumn(new ColumnBuilder("data2", DataType.TEXT))
+ .toTable(tempDb);
+
+ for(int i = 3; i < 6; ++i) {
+ t.addRow(i, "row" + i);
+ }
+
+ return true;
+
+ } else if("Table4".equals(tableName)) {
+
+ assertEquals("testFile2.txt", customFile);
+ return false;
+ }
+
+ return false;
+ }
+
+ @Override
+ protected Database createTempDb(Object customFile, FileFormat format,
+ boolean inMemory, File tempDir)
+ throws IOException
+ {
+ inMemory = "testFile1.txt".equals(customFile);
+ return super.createTempDb(customFile, format, inMemory, tempDir);
+ }
+ }
+}
projects / jackcess.git / commitdiff