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/*
* Copyright (C) 2017 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.
*/
package com.android.launcher3.model;
import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteException;
import android.util.Log;
import android.util.SparseArray;
import com.android.launcher3.provider.LauncherDbUtils.SQLiteTransaction;
import com.android.launcher3.util.IOUtils;
import org.json.JSONArray;
import org.json.JSONException;
import org.json.JSONObject;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.Collections;
/**
* Utility class to handle DB downgrade
*/
public class DbDowngradeHelper {
private static final String TAG = "DbDowngradeHelper";
private static final String KEY_VERSION = "version";
private static final String KEY_DOWNGRADE_TO = "downgrade_to_";
private final SparseArray<String[]> mStatements = new SparseArray<>();
public final int version;
private DbDowngradeHelper(int version) {
this.version = version;
}
public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) {
ArrayList<String> allCommands = new ArrayList<>();
for (int i = oldVersion - 1; i >= newVersion; i--) {
String[] commands = mStatements.get(i);
if (commands == null) {
throw new SQLiteException("Downgrade path not supported to version " + i);
}
Collections.addAll(allCommands, commands);
}
try (SQLiteTransaction t = new SQLiteTransaction(db)) {
for (String sql : allCommands) {
db.execSQL(sql);
}
t.commit();
}
}
public static DbDowngradeHelper parse(File file) throws JSONException, IOException {
JSONObject obj = new JSONObject(new String(IOUtils.toByteArray(file)));
DbDowngradeHelper helper = new DbDowngradeHelper(obj.getInt(KEY_VERSION));
for (int version = helper.version - 1; version > 0; version--) {
if (obj.has(KEY_DOWNGRADE_TO + version)) {
JSONArray statements = obj.getJSONArray(KEY_DOWNGRADE_TO + version);
String[] parsed = new String[statements.length()];
for (int i = 0; i < parsed.length; i++) {
parsed[i] = statements.getString(i);
}
helper.mStatements.put(version, parsed);
}
}
return helper;
}
public static void updateSchemaFile(File schemaFile, int expectedVersion,
Context context, int schemaResId) {
try {
if (DbDowngradeHelper.parse(schemaFile).version >= expectedVersion) {
return;
}
} catch (Exception e) {
// Schema error
}
// Write the updated schema
try (FileOutputStream fos = new FileOutputStream(schemaFile);
InputStream in = context.getResources().openRawResource(schemaResId)) {
IOUtils.copy(in, fos);
} catch (IOException e) {
Log.e(TAG, "Error writing schema file", e);
}
}
}
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