AssetDatabaseOpenHelper.java

/*
 * Copyright (c) 2014. Marshal Chen.
 */

package com.marshalchen.common.commonUtils.dbUtils;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import com.marshalchen.common.commonUtils.fileUtils.FileUtils;

import java.io.File;
import java.io.IOException;
import java.io.InputStream;

/**
 * AssetDatabaseOpenHelper
 * <ul>
 * <li>Auto copy databse form assets to /data/data/package_name/databases</li>
 * <li>You can use it like {@link android.database.sqlite.SQLiteDatabase}, use {@link #getWritableDatabase()} to create and/or open a database
 * that will be used for reading and writing. use {@link #getReadableDatabase()} to create and/or open a database that
 * will be used for reading only.</li>
 * </ul>
 *
 */
public class AssetDatabaseOpenHelper {

    private Context context;
    private String  databaseName;

    public AssetDatabaseOpenHelper(Context context, String databaseName) {
        this.context = context;
        this.databaseName = databaseName;
    }

    /**
     * Create and/or open a database that will be used for reading and writing.
     *
     * @return
     * @throws RuntimeException if cannot copy database from assets
     * @throws android.database.sqlite.SQLiteException if the database cannot be opened
     */
    public synchronized SQLiteDatabase getWritableDatabase() {
        File dbFile = context.getDatabasePath(databaseName);
        if (dbFile != null && !dbFile.exists()) {
            try {
                copyDatabase(dbFile);
            } catch (IOException e) {
                throw new RuntimeException("Error creating source database", e);
            }
        }

        return SQLiteDatabase.openDatabase(dbFile.getPath(), null, SQLiteDatabase.OPEN_READWRITE);
    }

    /**
     * Create and/or open a database that will be used for reading only.
     *
     * @return
     * @throws RuntimeException if cannot copy database from assets
     * @throws android.database.sqlite.SQLiteException if the database cannot be opened
     */
    public synchronized SQLiteDatabase getReadableDatabase() {
        File dbFile = context.getDatabasePath(databaseName);
        if (dbFile != null && !dbFile.exists()) {
            try {
                copyDatabase(dbFile);
            } catch (IOException e) {
                throw new RuntimeException("Error creating source database", e);
            }
        }

        return SQLiteDatabase.openDatabase(dbFile.getPath(), null, SQLiteDatabase.OPEN_READONLY);
    }

    /**
     * @return the database name
     */
    public String getDatabaseName() {
        return databaseName;
    }

    private void copyDatabase(File dbFile) throws IOException {
        InputStream stream = context.getAssets().open(databaseName);
        FileUtils.writeFile(dbFile, stream);
        stream.close();
    }
}