package cn.edu.tsinghua.hpc.tcontacts.provider;
/*
* Copyright (C) 2009 The Android Open Source Project
*
* 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.
*/
import android.content.res.AssetFileDescriptor;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;
import android.os.MemoryFile;
import android.os.ParcelFileDescriptor;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
/**
* Some helper functions for using SQLite database to implement content providers.
*
* @hide
*/
public class SQLiteContentHelper {
/**
* Runs an SQLite query and returns an AssetFileDescriptor for the
* blob in column 0 of the first row. If the first column does
* not contain a blob, an unspecified exception is thrown.
*
* @param db Handle to a readable database.
* @param sql SQL query, possibly with query arguments.
* @param selectionArgs Query argument values, or {@code null} for no argument.
* @return If no exception is thrown, a non-null AssetFileDescriptor is returned.
* @throws FileNotFoundException If the query returns no results or the
* value of column 0 is NULL, or if there is an error creating the
* asset file descriptor.
*/
public static AssetFileDescriptor getBlobColumnAsAssetFile(SQLiteDatabase db, String sql,
String[] selectionArgs) throws FileNotFoundException {
try {
MemoryFile file = simpleQueryForBlobMemoryFile(db, sql, selectionArgs);
if (file == null) {
throw new FileNotFoundException("No results.");
}
// XXX
// Use hack
Method methodFromMemoryFile = Class.forName("android.content.res.AssetFileDescriptor").getMethod("fromMemoryFile", new Class[] {MemoryFile.class});
methodFromMemoryFile.setAccessible(true);
AssetFileDescriptor fd = (AssetFileDescriptor) methodFromMemoryFile.invoke(null, new Object[] {file});
return fd;
} catch (IOException ex) {
throw new FileNotFoundException(ex.toString());
} catch (SecurityException e) {
} catch (NoSuchMethodException e) {
} catch (ClassNotFoundException e) {
} catch (IllegalArgumentException e) {
} catch (IllegalAccessException e) {
} catch (InvocationTargetException e) {
}
return null;
}
/**
* Runs an SQLite query and returns a MemoryFile for the
* blob in column 0 of the first row. If the first column does
* not contain a blob, an unspecified exception is thrown.
*
* @return A memory file, or {@code null} if the query returns no results
* or the value column 0 is NULL.
* @throws IOException If there is an error creating the memory file.
*/
// TODO: make this native and use the SQLite blob API to reduce copying
private static MemoryFile simpleQueryForBlobMemoryFile(SQLiteDatabase db, String sql,
String[] selectionArgs) throws IOException {
Cursor cursor = db.rawQuery(sql, selectionArgs);
if (cursor == null) {
return null;
}
try {
if (!cursor.moveToFirst()) {
return null;
}
byte[] bytes = cursor.getBlob(0);
if (bytes == null) {
return null;
}
MemoryFile file = new MemoryFile(null, bytes.length);
file.writeBytes(bytes, 0, 0, bytes.length);
// XXX
//file.deactivate();
return file;
} finally {
cursor.close();
}
}
}