Question

假设在我手机的内存中我有一个名为kc的文件夹，在那个kc文件夹中我有一个名为local.db的sqlite bd，现在我需要通过我的应用程序连接到该数据库，并且需要运行像select name这样的查询来自survey_master向我展示了主要活动onCreate方法的吐司结果。我怎么能这样做？

Answer 1

创建数据库并将其命名为 myDB.sqlite 并将其放入您的app资源文件夹。

DB-Manager类

public class AppsDatabaseManager extends SQLiteOpenHelper{

    public static final int VERSION = 1;
    private String DB_PATH = Environment.getExternalStorageDirectory().getAbsolutePath()+ "/yourFolderName";
    private static String DB_NAME = "myDB.sqlite";
    private SQLiteDatabase db;
    private Context context;

    public AppsDatabaseManager(Context context) {
        super(context, DB_NAME, null, VERSION);
        this.context = context;

        try {
            copyDataBase();
        } catch (IOException e) {
            e.printStackTrace();
        }

    }

    public boolean initializeDatabase() {
        if (DB_PATH == null)
            return false;

        try {
            db = SQLiteDatabase.openDatabase(DB_PATH + "/" + DB_NAME, null,
                    SQLiteDatabase.OPEN_READWRITE
                            | SQLiteDatabase.NO_LOCALIZED_COLLATORS);
        } catch (Exception ex) {
            ex.printStackTrace();
            return false;
        }

        return true;
    }


    private void copyDataBase() throws IOException {

        // Open your local db as the input stream
        InputStream myInput = context.getAssets().open(DB_NAME);

        // Path to the just created empty db
        String outFileName = DB_PATH + "/" + DB_NAME;

        // Open the empty db as the output stream
        new File(outFileName).createNewFile();
        OutputStream myOutput = new FileOutputStream(outFileName);

        // transfer bytes from the inputfile to the outputfile
        byte[] buffer = new byte[1024];
        int length;
        while ((length = myInput.read(buffer)) > 0) {
            myOutput.write(buffer, 0, length);
        }

        // Close the streams
        myOutput.flush();
        myOutput.close();
        myInput.close();
    }

}

在您的活动中：

AppsDatabaseManager dbManager = new AppsDatabaseManager(this);

if( dbManager.initializeDatabase() ){
    //
}

在宣言中提供权限：

<uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE" />

下载我的完整示例：GitRepo

在应用程序中使用外部sqlite数据库

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