Question

我创建了一个简单的应用程序，其中图像存储从ImageView到数据库。但是当点击retrive按钮时，显示索引1请求大小为3。我不知道出了什么问题。数据库类：

           @Override
    public void onCreate(SQLiteDatabase db) {
    String CREATE_IMAGE_TABLE = "CREATE TABLE " +TABLE_NAME  + "("
            + IMAGE_KEY + " BLOB )";
     db.execSQL(CREATE_IMAGE_TABLE);
     }
        @Override
       public void onUpgrade(SQLiteDatabase db, int i, int i1) {
     db.execSQL("DROP TABLE IF EXISTS "+TABLE_NAME);
     onCreate(db);

    }
     public  boolean insertData(byte[]image )throws SQLiteException
     {
    SQLiteDatabase db = this.getWritableDatabase();


    ContentValues cv=new ContentValues();
    cv.put(IMAGE_KEY,image);
    long result= db.insert(TABLE_NAME,null,cv);
    if(result==-1)
        return false;
    else
        return true;

   }
  public Cursor getAllData()
  {
    SQLiteDatabase db=this.getReadableDatabase();
    Cursor res=db.rawQuery("select * from "+TABLE_NAME,null);
    byte[]img=res.getBlob(0);
    return res;
  }

这是活动类：

           public void button2(View view)
            {
            try {

             Cursor res = myDb.getAllData();
            if (res ==null) {
            showMessage("error", "no data found");
            } else {
            StringBuffer buffer = new StringBuffer();
            while (res.moveToNext()) {
                buffer.append("id:" + res.getBlob(0) + "\n");
                byte[] image = res.getBlob(0);

                Bitmap bmp = BitmapFactory.decodeByteArray(image, 0,
                                 image.length); 


                imagee.setImageBitmap(bmp);

            }
            // showMessage("DATA", buffer.toString());
            }
           }
            catch (Exception e)
            {
          Toast.makeText(getBaseContext(),e.getMessage(),
                  Toast.LENGTH_LONG).show();
                    }}

              public  void buttonn(View view)
     {
      Bitmap bitmap = ((BitmapDrawable) imagee.getDrawable()).getBitmap();
      ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
      bitmap.compress(Bitmap.CompressFormat.PNG, 0, outputStream);
      byte[] data = outputStream.toByteArray();
            boolean isInserted = myDb.insertData(data);

          if (isInserted == true)
        Toast.makeText(getBaseContext(), "Registration Succes!",
              Toast.LENGTH_SHORT).show();
            else 

           Toast.makeText(getBaseContext(), "No Record Registered!",
               Toast.LENGTH_SHORT).show();     

                }
                  }

我尝试了最多但不能做的事情。我从res.movetoNext更改它但显示相同的错误并使用res.movetoFirst它也显示相同的错误

Answer 1

Android sqlite CursorWindow在大多数配置中都有一个固定大小的缓冲区，大小为2MB。你不能移动任何大于那的行。

不要在Android sqlite中存储大型二进制数据，如图像。请改用外部存储，只需在数据库中保存路径即可。

Answer 2

检查此代码，了解如何在android中保存图像：

private String saveToInternalStorage(Bitmap bitmapImage){
        ContextWrapper cw = new ContextWrapper(getApplicationContext());
         // path to /data/data/yourapp/app_data/imageDir
        File directory = cw.getDir("imageDir", Context.MODE_PRIVATE);
        // Create imageDir
        File mypath=new File(directory,"profile.jpg");

        FileOutputStream fos = null;
        try {           
            fos = new FileOutputStream(mypath);
       // Use the compress method on the BitMap object to write image to the OutputStream
            bitmapImage.compress(Bitmap.CompressFormat.PNG, 100, fos);
        } catch (Exception e) {
              e.printStackTrace();
        } finally {
              fos.close(); 
        } 
        return directory.getAbsolutePath();
    }

您只需将图像的路径添加到数据库中，而不是blob图像。

参考：Saving and Reading Bitmaps/Images from Internal memory in Android

请求索引1，大小为3

2 个答案: