這種方法的含義是什么？

Question

這是我的全部代碼：

public class photo extends Activity implements View.OnClickListener {

ImageView iv;
Button bt;
ImageButton ib;
Intent i ;
Bitmap bmp;
final static int cameraData =0;
@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    super.onCreate(savedInstanceState);
    intsallttion();

}
private void intsallttion() {
    // TODO Auto-generated method stub
    iv = (ImageView) findViewById(R.id.iv);
    bt = (Button) findViewById(R.id.bt);
    ib = (ImageButton) findViewById(R.id.ib);

    bt.setOnClickListener(this);
    ib.setOnClickListener(this);
}

@Override
public void onClick(View v) {
    switch(v.getId()){
    case R.id.bt:

        break;

    case R.id.ib:
        i = new Intent(android.provider.MediaStore.ACTION_IMAGE_CAPTURE);
        startActivityForResult(i,cameraData);
        break;
    }
}

@Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode==RESULT_OK){
        Bundle extras = data.getExtras();
        bmp = (Bitmap) extras.get("data");
        iv.setImageBitmap(bmp);
    }
}
}

我不明白這種方法：

    @Override
protected void onActivityResult(int requestCode, int resultCode, Intent data) {
    // TODO Auto-generated method stub
    super.onActivityResult(requestCode, resultCode, data);
    if(resultCode==RESULT_OK){
        Bundle extras = data.getExtras();
        bmp = (Bitmap) extras.get("data");
        iv.setImageBitmap(bmp);
    }
}

這種方法有什么作用？

Answer 1

根據您的代碼，您正在調用相機捕獲圖像。 由於您使用startActivityForResult啟動了攝像機活動，因此您期望攝像機活動返回一些結果。

當圖像被進來的活動捕獲時，將使用捕獲的結果（圖像）調用startActivityForResult。

Answer 2

startActivityForResult調用android的內部意圖（在您的情況下，是打開相機，用戶可以拍照）。

拍照后，它將控制權返回給onActivityResult處理程序，您可以在其中檢查resultCode是否為RESULT_OK並采取必要的操作，例如在您的示例中使用iv.setImageBitmap(bmp);在ImageView上設置圖像iv.setImageBitmap(bmp);

Answer 3

您通過startActivityForResult打開了攝像機的活動，然后正如Libin startActivityForResult那樣，您在那里得到了結果； 結果就是圖片。 我試圖添加一些評論：

     @Override
     protected void onActivityResult(int requestCode, int resultCode, Intent data) {
     // TODO Auto-generated method stub
      super.onActivityResult(requestCode, resultCode, data);
      // you check the result code that you got from the activity of the camera
      // If the user took successfully a picture you get RESULT_OK else RESULT_CANCELED
      if(resultCode==RESULT_OK){
           // The picture is communicated from the activity of the camera to your activity 
           // by intent as an extras Bundle : you put this bundle in bundle
           Bundle extras = data.getExtras();
           // you take the bitmap (your picture is in format bitmap)form this extras 
           bmp = (Bitmap) extras.get("data");
           // you are showing the bitmap in the ImageView iv
           iv.setImageBitmap(bmp);
    }
}