1 /* 2 * Copyright (C) 2017 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 package com.android.launcher3.model; 17 18 import android.content.Context; 19 import android.database.sqlite.SQLiteDatabase; 20 import android.database.sqlite.SQLiteException; 21 import android.util.Log; 22 import android.util.SparseArray; 23 24 import com.android.launcher3.R; 25 import com.android.launcher3.provider.LauncherDbUtils.SQLiteTransaction; 26 import com.android.launcher3.util.IOUtils; 27 28 import org.json.JSONArray; 29 import org.json.JSONException; 30 import org.json.JSONObject; 31 32 import java.io.File; 33 import java.io.FileOutputStream; 34 import java.io.IOException; 35 import java.io.InputStream; 36 import java.util.ArrayList; 37 import java.util.Collections; 38 39 /** 40 * Utility class to handle DB downgrade 41 */ 42 public class DbDowngradeHelper { 43 44 private static final String TAG = "DbDowngradeHelper"; 45 46 private static final String KEY_VERSION = "version"; 47 private static final String KEY_DOWNGRADE_TO = "downgrade_to_"; 48 49 private final SparseArray<String[]> mStatements = new SparseArray<>(); 50 public final int version; 51 DbDowngradeHelper(int version)52 private DbDowngradeHelper(int version) { 53 this.version = version; 54 } 55 onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion)56 public void onDowngrade(SQLiteDatabase db, int oldVersion, int newVersion) { 57 ArrayList<String> allCommands = new ArrayList<>(); 58 59 for (int i = oldVersion - 1; i >= newVersion; i--) { 60 String[] commands = mStatements.get(i); 61 if (commands == null) { 62 throw new SQLiteException("Downgrade path not supported to version " + i); 63 } 64 Collections.addAll(allCommands, commands); 65 } 66 67 try (SQLiteTransaction t = new SQLiteTransaction(db)) { 68 for (String sql : allCommands) { 69 db.execSQL(sql); 70 } 71 t.commit(); 72 } 73 } 74 parse(File file)75 public static DbDowngradeHelper parse(File file) throws JSONException, IOException { 76 JSONObject obj = new JSONObject(new String(IOUtils.toByteArray(file))); 77 DbDowngradeHelper helper = new DbDowngradeHelper(obj.getInt(KEY_VERSION)); 78 for (int version = helper.version - 1; version > 0; version--) { 79 if (obj.has(KEY_DOWNGRADE_TO + version)) { 80 JSONArray statements = obj.getJSONArray(KEY_DOWNGRADE_TO + version); 81 String[] parsed = new String[statements.length()]; 82 for (int i = 0; i < parsed.length; i++) { 83 parsed[i] = statements.getString(i); 84 } 85 helper.mStatements.put(version, parsed); 86 } 87 } 88 return helper; 89 } 90 updateSchemaFile(File schemaFile, int expectedVersion, Context context)91 public static void updateSchemaFile(File schemaFile, int expectedVersion, Context context) { 92 try { 93 if (DbDowngradeHelper.parse(schemaFile).version >= expectedVersion) { 94 return; 95 } 96 } catch (Exception e) { 97 // Schema error 98 } 99 100 // Write the updated schema 101 try (FileOutputStream fos = new FileOutputStream(schemaFile); 102 InputStream in = context.getResources().openRawResource(R.raw.downgrade_schema)) { 103 IOUtils.copy(in, fos); 104 } catch (IOException e) { 105 Log.e(TAG, "Error writing schema file", e); 106 } 107 } 108 } 109