從現有數據庫檢索數據並將其填充到列表視圖

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我想從我的數據庫中檢索我的sqlite數據，並且我想將其填充到listview中。我遵循教程並實現了代碼。我創建了一個名爲MYCATEGORY.db的數據庫並將其複製到我的資產文件夾中。但我得到異常「從資源文件」複製數據庫的問題。從現有數據庫檢索數據並將其填充到列表視圖

我的主要activity.java

public class MainActivity extends ActionBarActivity { 

    private DBHelper dbhelper = null; 
    private Cursor ourCursor = null; 
    private DBAdapter adapter= null; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 

     super.onCreate(savedInstanceState); 
     setContentView(R.layout.activity_main); 
     ListView myListView = (ListView) findViewById(R.id.listView1);  
     dbhelper = new DBHelper(this); 
     dbhelper.createDatabase(); 
     dbhelper .openDataBase(); 
     ourCursor = dbhelper .getCursor(); 
     startManagingCursor(ourCursor); 
     adapter= new DBAdapter (ourCursor); 
     myListView.setAdapter(adapter); 
    } 

    class DBAdapter extends CursorAdapter { 

     DBAdapter (Cursor c){ 

      super(MainActivity.this, c);    
     } 

     public void bindView(View row, Context ctxt, Cursor c) { 

      DBHolder holder =(DBHolder)row.getTag(); 
      holder.populateFrom(c,dbhelper); 
     } 

     @Override 
     public View newView(Context ctxt, Cursor c, ViewGroup parent) { 

      LayoutInflater inflater=getLayoutInflater(); 
      View row =inflater.inflate(R.layout.row,parent,false); 
      DBHolder holder =new DBHolder(row); 
      row.setTag(holder); 
      return (row); 
     } 
    } 

    static class DBHolder { 

     private TextView name=null; 
     DBHolder(View row){ 

      name=(TextView)row.findViewById(R.id.textView1); 
     } 

     void populateFrom(Cursor c,DBHelper r){ 

      name.setText(r.getName(c)); 
     } 
    } 
}

DBHelper.java

public class DBHelper extends SQLiteOpenHelper { 

     private static final String DATABASE_PATH = "/data/data/com.example.databaseapp/databases/"; 

    private static final String DATABASE_NAME= "MYCATEGORY.db"; 
    private static final String TABLE_NAME = "MYMAINTABLE"; 

    private static final String COLUMN_ID = "cat_id"; 
    private static final String COLUMN_NAME= "cat_name"; 
    private static final int SCHEMA_VERSION = 1; 
    public SQLiteDatabase dbSqlite; 
    private final Context myContext; 

    public DBHelper(Context context) { 

     super(context, DATABASE_NAME, null, SCHEMA_VERSION); 
     this.myContext =context ; 
    } 

    @Override 
    public void onCreate(SQLiteDatabase db) {} 

    @Override 
    public void onUpgrade(SQLiteDatabase arg0, int arg1, int arg2) {} 

    void createDatabase() { 

     createDB(); 
    } 

    private void createDB() { 

     boolean dbExist =DBExists(); 
     if(!dbExist){ 

      this.getReadableDatabase(); 
      copyDBFromResource(); 
     } 
    } 

    private boolean DBExists(){ 

     SQLiteDatabase db=null; 
     try { 

      String databasePath =DATABASE_PATH + DATABASE_NAME ; 
      db = SQLiteDatabase .openDatabase(databasePath, null, SQLiteDatabase.OPEN_READWRITE); 
      db.setLocale(Locale.getDefault()); 
      db.setLockingEnabled(true); 
      db.setVersion(1); 
     } 
     catch(SQLException e) { 

      Log.e("sqlHelpeer ","database not found"); 
     } 
     if(db != null){ 

      db.close(); 
     } 
     return db!=null ? true :false; 
    } 

    private void copyDBFromResource(){ 

     InputStream inputstream = null; 
     OutputStream outputstream = null; 
     String dbFilePath = DATABASE_PATH +DATABASE_NAME; 
     try{ 

      inputstream =myContext .getAssets() .open(DATABASE_NAME); 
      outputstream =new FileOutputStream(dbFilePath); 
      byte[] buffer =new byte[1024]; 
      int length; 
      while ((length=inputstream.read(buffer)) > 0){ 

       outputstream.write(buffer,0,length); 
      } 
      outputstream.flush(); 
      outputstream.close(); 
      inputstream.close(); 
     } 
     catch(IOException e){ 

      throw new Error("problem copyingg database from resource file"); 
     } 
    } 

    public void openDataBase() throws SQLException{ 

     String myPath =DATABASE_PATH + DATABASE_NAME; 
     dbSqlite = SQLiteDatabase.openDatabase(myPath,null,SQLiteDatabase.OPEN_READWRITE); 
    } 

    public synchronized void close(){ 

     if(dbSqlite != null) { 

      dbSqlite.close(); 
     } 
     super.close(); 
    } 

    public Cursor getCursor(){ 

     SQLiteQueryBuilder queryBulider = new SQLiteQueryBuilder(); 
     queryBulider .setTables(TABLE_NAME); 
     String[] asColumnsToReturn = new String[] {COLUMN_ID,COLUMN_NAME}; 
     Cursor mCursor =queryBulider.query(dbSqlite, asColumnsToReturn, null, null,   null,null,"cat_name ASC"); 
     return mCursor; 
    } 

    public String getName(Cursor c) { 

     return(c.getString(1)); 
    } 
}

這是我的日誌貓

11-25 14:21:27.095: W/dalvikvm(18936): threadid=1: thread exiting with uncaught exception (group=0x40c89a68) 
11-25 14:21:27.095: E/AndroidRuntime(18936): FATAL EXCEPTION: main 
11-25 14:21:27.095: E/AndroidRuntime(18936): java.lang.Error: problem copyingg database from resource file 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.example.androiddatabaselist.DBHelper.copyDBFromResource(DBHelper.java:92) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.example.androiddatabaselist.DBHelper.createDB(DBHelper.java:52) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.example.androiddatabaselist.DBHelper.createDatabase(DBHelper.java:45) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.example.androiddatabaselist.MainActivity.onCreate(MainActivity.java:26) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.Activity.performCreate(Activity.java:4470) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.Instrumentation.callActivityOnCreate(Instrumentation.java:1053) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.ActivityThread.performLaunchActivity(ActivityThread.java:1934) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.ActivityThread.handleLaunchActivity(ActivityThread.java:1995) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.ActivityThread.access$600(ActivityThread.java:128) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.ActivityThread$H.handleMessage(ActivityThread.java:1161) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.os.Handler.dispatchMessage(Handler.java:99) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.os.Looper.loop(Looper.java:137) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at android.app.ActivityThread.main(ActivityThread.java:4514) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at java.lang.reflect.Method.invokeNative(Native Method) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at java.lang.reflect.Method.invoke(Method.java:511) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.android.internal.os.ZygoteInit$MethodAndArgsCaller.run(ZygoteInit.java:980) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at com.android.internal.os.ZygoteInit.main(ZygoteInit.java:747) 
11-25 14:21:27.095: E/AndroidRuntime(18936): at dalvik.system.NativeStart.main(Native Method)

來源

2014-11-25 Thushara prasad

檢查：https://github.com/jgilfelt/android-sqlite-asset-helper – 2014-11-25 09:01:55

，而不是拋出新的錯誤，whold你的通過打印e.stacktrace（）檢查你的代碼拋出了什麼異常？ – Darpan 2014-11-25 09:04:14

更新您的數據庫路徑。使用這個代替

ContextWrapper cw =new ContextWrapper(getApplicationContext()); 
DB_PATH =cw.getFilesDir().getAbsolutePath()+ "/databases/";

或者你可以用這個太

String outFileName = context.getDatabasePath() + dbname;

來源

2014-11-25 09:09:31

你DATABASE_PATH是錯誤的。它應該是從/開始的絕對路徑，

DATABASE_PATH = "/data/data/com.example.databaseapp/databases/"

你也應該如果該目錄嘗試複製文件之前存在檢查。 E.g

File file = new File(DATABASE_PATH); 
    file.mkdirs(); 
    file.mkdir(); 
    outputstream =new FileOutputStream(new File(file, DATABASE_NAME));

而不是硬編碼的數據庫路徑，你應該使用Context.getDatabasePath(String name)，像

mContext.getDatabasePath(mDataBaseName)

來源

2014-11-25 09:03:21 Blackbelt

好的，我編輯了我的軟件包名稱..但在哪裏添加此行mContext.getDatabasePath（mDataBaseName）.. – 2014-11-25 09:25:17

你不必強迫它。伊莫它只是一個良好的做法 – Blackbelt 2014-11-25 09:27:28

，但它顯示相同的錯誤.. – 2014-11-25 09:31:58

我覺得你在這裏給了錯誤的數據庫名稱DATABASE_NAME =「MYCATEGORY.db」。請檢查您的數據庫名稱是否爲「MYCATEGORY.db」。

來源

2014-11-25 09:04:46

不，我檢查它沒有數據庫名稱的問題.. – 2014-11-25 09:31:12

從現有數據庫檢索數據並將其填充到列表視圖

回答

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