Question

考虑到我的应用程序仍在开发中，有时会出现错误，这会影响我与应用程序连接的数据库。因为我已经测试了数据，所以每次出错都不想输入，我想实现一个简单的导入/导出功能。

我最近偶然发现this问题，这或多或少是我想要的。我告诉你我的代码实现了。导出功能工作正常，我可以使用来自android市场的SQLIte Database应用程序进行测试。问题是导入。它告诉我Toast，一切都很顺利，但没有任何反应。不过，我不太确定我是否做得对。

在MainMenuActivity我实施了以下方法：

(...)

public boolean onCreateOptionsMenu(Menu menu){
    menu.add(1, Menu.FIRST, Menu.FIRST, "backup DB").setIcon(R.drawable.ic_action_save);
    menu.add(1, Menu.FIRST+1, Menu.FIRST+1, "import DB").setIcon(R.drawable.ic_action_upload);
    return super.onCreateOptionsMenu(menu);
}

(...)

public boolean onOptionsItemSelected(MenuItem item){
    switch(item.getItemId()){
    case 1:
        backupDatabase();
        return true;
    case 2:
        importDatabase();
        return true;
        default:
        break;
    }
    return super.onOptionsItemSelected(item);
}


private void backupDatabase(){
    try{
         File sd = Environment.getExternalStorageDirectory();
         File data = Environment.getDataDirectory();

         if (sd.canWrite()) {
             String currentDBPath = "//data//challenge.main//databases//DBCHALLENGES";
             String backupDBPath = "DBCHALLENGES";
             File currentDB = new File(data, currentDBPath);
             File backupDB = new File(sd, backupDBPath);

             FileChannel src = new FileInputStream(currentDB).getChannel();
             FileChannel dst = new FileOutputStream(backupDB).getChannel();
             dst.transferFrom(src, 0, src.size());
             src.close();
             dst.close();
             Toast.makeText(getBaseContext(), "Successfully backed up database!", Toast.LENGTH_LONG).show();
         }
    }catch (IOException e){
        Toast.makeText(getBaseContext(), "Error in backing up database!", Toast.LENGTH_LONG).show();
    }
}


private void importDatabase(){
    datasource = new CustomDataSource(this);
    datasource.open();
    try{
        datasource.importDatabase("DBCHALLENGES");
        Toast.makeText(getBaseContext(), "Successfully imported database!", Toast.LENGTH_LONG).show();
    }catch (IOException e){
        Toast.makeText(getBaseContext(), "Error in importing database!", Toast.LENGTH_LONG).show();
    }finally{
        datasource.close();
    }
}

在CustomDataSource：

中

public boolean importDatabase(String dbPath) throws IOException{
    return dbHelper.importDatabase(dbPath);
}

最后在DBHelper扩展SQLiteOpenHelper

public boolean importDatabase(String dbPath) throws IOException{
    close();
    File newDB = new File(dbPath);
    File oldDB = new File("//data//challenge.main//databases//DBCHALLENGES");
    if(newDB.exists()){
        FileUtils.copyFile(new FileInputStream(newDB), new FileOutputStream(oldDB));
        getWritableDatabase().close();
        return true;
    }

    return false;
}

但是，按下导入Button，会显示正Toast，表示导入成功。但我之前空的申请仍然是空的。备份数据库应该位于内部存储的第一级，它的作用。我想，也许我对这些路径感到困惑，但我无法完全了解它。

Answer 1

试试这个：

private void importDatabase(String inputFileName) throws IOException
{
    InputStream mInput = new FileInputStream(inputFileName);
    String outFileName = YOUR_DB_PATH_HERE;
    OutputStream mOutput = new FileOutputStream(outFileName);
    byte[] mBuffer = new byte[1024];
    int mLength;
    while ((mLength = mInput.read(mBuffer))>0)
    {
        mOutput.write(mBuffer, 0, mLength);
    }
    mOutput.flush();
    mOutput.close();
    mInput.close();
}

sqlite数据库的简单导入/导出选项

1 个答案: