Class.forName("com.mysql.jdbc.Driver");
                try(Connection con = DriverManager.getConnection("jdbc:mysql://localhost:3306/sys", "root", "Elior204")){
                    Statement stmt = con.createStatement();
                    ResultSet rs = stmt.executeQuery("SELECT img FROM Sentences where id=1");
                       ImageView image = (ImageView) findViewById(R.id.imageView1);
                    Blob b =rs.getBlob(1);
                    int blobLength = (int) b.length();
                    byte[] blobAsBytes = b.getBytes(1, blobLength);
                    Bitmap btm =BitmapFactory.decodeByteArray(blobAsBytes,0,blobAsBytes.length);
                    image.setImageBitmap(btm );
                    con.close();

java.sql.Blob blob = rs.getBlob(1);
byte[] imageContents = blob.getBytes(1, new Integer(blob.length()).intValue());

image = (ImageView) findViewById(R.id.imageView1);

 button = (Button) findViewById(R.id.btnChangeImage);
 button.setOnClickListener(new OnClickListener() {

    @Override
    public void onClick(View arg0) {
          java.io.File tmpFileForImage = java.io.File.createTemporaryFile("image", ".png"); // or whatever your extension happens to be
          java.io.BufferedOutputStream bos = new java.io.BufferedOutputStream(new java.io.FileOutputStream(tmpFileForImage);
          bos.write(imageContents);
          bos.close();
          image.setImageResource(tmpFileForImage.getAbsolutePath());
    });