Java tutorial
/* * Firetweet - Twitter client for Android * * Copyright (C) 2012-2014 Mariotaku Lee <mariotaku.lee@gmail.com> * * This program is free software: you can redistribute it and/or modify * it under the terms of the GNU General Public License as published by * the Free Software Foundation, either version 3 of the License, or * (at your option) any later version. * * This program is distributed in the hope that it will be useful, * but WITHOUT ANY WARRANTY; without even the implied warranty of * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the * GNU General Public License for more details. * * You should have received a copy of the GNU General Public License * along with this program. If not, see <http://www.gnu.org/licenses/>. */ package org.getlantern.firetweet.util.content; import android.database.Cursor; import android.database.sqlite.SQLiteDatabase; import android.text.TextUtils; import org.apache.commons.lang3.ArrayUtils; import org.getlantern.querybuilder.Columns; import org.getlantern.querybuilder.Columns.Column; import org.getlantern.querybuilder.Expression; import org.getlantern.querybuilder.NewColumn; import org.getlantern.querybuilder.OnConflict; import org.getlantern.querybuilder.Tables; import org.getlantern.querybuilder.query.SQLInsertQuery; import org.getlantern.querybuilder.query.SQLSelectQuery; import org.getlantern.firetweet.util.FiretweetArrayUtils; import java.util.ArrayList; import java.util.Collections; import java.util.HashMap; import java.util.List; import java.util.Locale; import java.util.Map; import static org.getlantern.querybuilder.SQLQueryBuilder.alterTable; import static org.getlantern.querybuilder.SQLQueryBuilder.createTable; import static org.getlantern.querybuilder.SQLQueryBuilder.dropTable; import static org.getlantern.querybuilder.SQLQueryBuilder.insertInto; import static org.getlantern.querybuilder.SQLQueryBuilder.select; public final class DatabaseUpgradeHelper { public static void safeUpgrade(final SQLiteDatabase db, final String table, final String[] newColNames, final String[] newColTypes, final boolean dropDirectly, final boolean strictMode, final Map<String, String> colAliases) { safeUpgrade(db, table, newColNames, newColTypes, dropDirectly, strictMode, colAliases, OnConflict.REPLACE); } public static void safeUpgrade(final SQLiteDatabase db, final String table, final String[] newColNames, final String[] newColTypes, final boolean dropDirectly, final boolean strictMode, final Map<String, String> colAliases, final OnConflict onConflict) { if (newColNames == null || newColTypes == null || newColNames.length != newColTypes.length) throw new IllegalArgumentException( "Invalid parameters for upgrading table " + table + ", length of columns and types not match."); // First, create the table if not exists. final NewColumn[] newCols = NewColumn.createNewColumns(newColNames, newColTypes); final String createQuery = createTable(true, table).columns(newCols).buildSQL(); db.execSQL(createQuery); // We need to get all data from old table. final String[] oldCols = getColumnNames(db, table); if (strictMode) { final String oldCreate = getCreateSQL(db, table); final Map<String, String> map = getTypeMapByCreateQuery(oldCreate); boolean differenct = false; for (final NewColumn newCol : newCols) { if (!newCol.getType().equalsIgnoreCase(map.get(newCol.getName()))) { differenct = true; } } if (!differenct) return; } else if (oldCols == null || FiretweetArrayUtils.contentMatch(newColNames, oldCols)) return; if (dropDirectly) { db.beginTransaction(); db.execSQL(dropTable(true, table).getSQL()); db.execSQL(createQuery); db.setTransactionSuccessful(); db.endTransaction(); return; } final String tempTable = String.format(Locale.US, "temp_%s_%d", table, System.currentTimeMillis()); db.beginTransaction(); db.execSQL(alterTable(table).renameTo(tempTable).buildSQL()); db.execSQL(createQuery); final String[] notNullCols = getNotNullColumns(newCols); final String insertQuery = createInsertDataQuery(table, tempTable, newColNames, oldCols, colAliases, notNullCols, onConflict); if (insertQuery != null) { db.execSQL(insertQuery); } db.execSQL(dropTable(true, tempTable).getSQL()); db.setTransactionSuccessful(); db.endTransaction(); } public static void safeUpgrade(final SQLiteDatabase db, final String table, final String[] newColNames, final String[] newColTypes, final boolean dropDirectly, final Map<String, String> colAliases) { safeUpgrade(db, table, newColNames, newColTypes, dropDirectly, true, colAliases, OnConflict.REPLACE); } private static String createInsertDataQuery(final String table, final String tempTable, final String[] newCols, final String[] oldCols, final Map<String, String> colAliases, final String[] notNullCols, final OnConflict onConflict) { final SQLInsertQuery.Builder qb = insertInto(onConflict, table); final List<String> newInsertColsList = new ArrayList<>(); for (final String newCol : newCols) { final String oldAliasedCol = colAliases != null ? colAliases.get(newCol) : null; if (ArrayUtils.contains(oldCols, newCol) || oldAliasedCol != null && ArrayUtils.contains(oldCols, oldAliasedCol)) { newInsertColsList.add(newCol); } } final String[] newInsertCols = newInsertColsList.toArray(new String[newInsertColsList.size()]); if (!FiretweetArrayUtils.contains(newInsertCols, notNullCols)) return null; qb.columns(newInsertCols); final Columns.Column[] oldDataCols = new Columns.Column[newInsertCols.length]; for (int i = 0, j = oldDataCols.length; i < j; i++) { final String newCol = newInsertCols[i]; final String oldAliasedCol = colAliases != null ? colAliases.get(newCol) : null; if (oldAliasedCol != null && ArrayUtils.contains(oldCols, oldAliasedCol)) { oldDataCols[i] = new Columns.Column(oldAliasedCol, newCol); } else { oldDataCols[i] = new Columns.Column(newCol); } } final SQLSelectQuery.Builder selectOldBuilder = select(new Columns(oldDataCols)); selectOldBuilder.from(new Tables(tempTable)); qb.select(selectOldBuilder.build()); return qb.buildSQL(); } private static String[] getColumnNames(final SQLiteDatabase db, final String table) { final Cursor cur = db.query(table, null, null, null, null, null, null, "1"); if (cur == null) return null; try { return cur.getColumnNames(); } finally { cur.close(); } } private static String getCreateSQL(final SQLiteDatabase db, final String table) { final SQLSelectQuery.Builder qb = select(new Column("sql")); qb.from(new Tables("sqlite_master")); qb.where(new Expression("type = ? AND name = ?")); final Cursor c = db.rawQuery(qb.buildSQL(), new String[] { "table", table }); if (c == null) return null; try { if (c.moveToFirst()) return c.getString(0); return null; } finally { c.close(); } } private static String[] getNotNullColumns(final NewColumn[] newCols) { if (newCols == null) return null; final String[] notNullCols = new String[newCols.length]; int count = 0; for (final NewColumn column : newCols) { if (column.getType().endsWith(" NOT NULL")) { notNullCols[count++] = column.getName(); } } return FiretweetArrayUtils.subArray(notNullCols, 0, count); } private static Map<String, String> getTypeMapByCreateQuery(final String query) { if (TextUtils.isEmpty(query)) return Collections.emptyMap(); final int start = query.indexOf("("), end = query.lastIndexOf(")"); if (start < 0 || end < 0) return Collections.emptyMap(); final HashMap<String, String> map = new HashMap<>(); for (final String segment : query.substring(start + 1, end).split(",")) { final String trimmed = segment.trim().replaceAll(" +", " "); final int idx = trimmed.indexOf(" "); map.put(trimmed.substring(0, idx), trimmed.substring(idx + 1, trimmed.length())); } return map; } }