diff options
Diffstat (limited to 'src/com/android/launcher3/model/DbDowngradeHelper.java')
-rw-r--r-- | src/com/android/launcher3/model/DbDowngradeHelper.java | 108 |
1 files changed, 108 insertions, 0 deletions
diff --git a/src/com/android/launcher3/model/DbDowngradeHelper.java b/src/com/android/launcher3/model/DbDowngradeHelper.java new file mode 100644 index 000000000..cd86b728b --- /dev/null +++ b/src/com/android/launcher3/model/DbDowngradeHelper.java @@ -0,0 +1,108 @@ +/* + * 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); + } + } +} |