在 Android 上简单导出和导入 SQLite 数据库 [英] Simple export and import of a SQLite database on Android

问题描述

我正在尝试实现一个简单的 SQLite 导出/导入以用于备份目的.导出只是存储原始 current.db 文件副本的问题.我想要做的导入只是删除旧的 current.db 文件并将 imported.db 文件重命名为 current.db.这可能吗?当我尝试此解决方案时，出现以下错误:

I am trying to implement a simple SQLite export/import for backup purposes. Export is just a matter of storing a copy of the raw current.db file. What I want to do for import is to just delete the old current.db file and rename the imported.db file to current.db. Is this possible? When I try this solution, I get the following error:

06-30 13:33:38.831: ERROR/SQLiteOpenHelper(23570):
    android.database.sqlite.SQLiteDatabaseCorruptException: error code 11: database disk image is malformed

如果我在 SQLite 浏览器中查看原始数据库文件，它看起来不错.

If I look at the raw database file in a SQLite browser it looks fine.

推荐答案

我在我的一个应用程序的 SQLiteOpenHelper 中使用此代码来导入数据库文件.

I use this code in the SQLiteOpenHelper in one of my applications to import a database file.

我将我的 FileUtils.copyFile() 方法粘贴到问题中.

I pasted my FileUtils.copyFile() method into the question.

SQLiteOpenHelper

public static String DB_FILEPATH = "/data/data/{package_name}/databases/database.db";

/**
 * Copies the database file at the specified location over the current
 * internal application database.
 * */
public boolean importDatabase(String dbPath) throws IOException {

    // Close the SQLiteOpenHelper so it will commit the created empty
    // database to internal storage.
    close();
    File newDb = new File(dbPath);
    File oldDb = new File(DB_FILEPATH);
    if (newDb.exists()) {
        FileUtils.copyFile(new FileInputStream(newDb), new FileOutputStream(oldDb));
        // Access the copied database so SQLiteHelper will cache it and mark
        // it as created.
        getWritableDatabase().close();
        return true;
    }
    return false;
}

FileUtils

public class FileUtils {
    /**
     * Creates the specified <code>toFile</code> as a byte for byte copy of the
     * <code>fromFile</code>. If <code>toFile</code> already exists, then it
     * will be replaced with a copy of <code>fromFile</code>. The name and path
     * of <code>toFile</code> will be that of <code>toFile</code>.<br/>
     * <br/>
     * <i> Note: <code>fromFile</code> and <code>toFile</code> will be closed by
     * this function.</i>
     * 
     * @param fromFile
     *            - FileInputStream for the file to copy from.
     * @param toFile
     *            - FileInputStream for the file to copy to.
     */
    public static void copyFile(FileInputStream fromFile, FileOutputStream toFile) throws IOException {
        FileChannel fromChannel = null;
        FileChannel toChannel = null;
        try {
            fromChannel = fromFile.getChannel();
            toChannel = toFile.getChannel();
            fromChannel.transferTo(0, fromChannel.size(), toChannel);
        } finally {
            try {
                if (fromChannel != null) {
                    fromChannel.close();
                }
            } finally {
                if (toChannel != null) {
                    toChannel.close();
                }
            }
        }
    }
}

如有必要，不要忘记删除旧的数据库文件.

Don't forget to delete the old database file if necessary.

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