Android：即使设置可见，进度条也不显示。

Question

我正在开发一个Android项目，当用户上传图片时，我想显示一个进度条。但是，即使在设置show进度条后，它也不起作用。我究竟做错了什么？

代码：

private ProgressBar spinner; 

    @Override 
    protected void onCreate(Bundle savedInstanceState) { 
     super.onCreate(savedInstanceState); 
     setContentView(R.layout.add_restaurant_images); 

     spinner=(ProgressBar)findViewById(R.id.progressBar); 
     spinner.setVisibility(View.GONE); 
    // Rest of the non-relevant to problem code 
} 

     private void uploadImage(boolean profilePhoto) { 
      spinner.setVisibility(View.VISIBLE); 
      if (!(reducedSizeBitmap == null)) { 
       reducedSizeBitmap.compress(Bitmap.CompressFormat.PNG, 100, stream); 
       byte[] byteArray = stream.toByteArray(); 
       this.restaurantService.addRestaurantImage(byteArray, profilePhoto); 
      } 
      spinner.setVisibility(View.GONE); 

     } 

XML文件：

<android.support.v4.widget.DrawerLayout xmlns:android="http://schemas.android.com/apk/res/android" 
    xmlns:app="http://schemas.android.com/apk/res-auto" 
    android:id="@+id/restaurant_drawer_layout" 
    android:layout_width="match_parent" 
    android:layout_height="match_parent"> 


    <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android" 
     android:layout_width="match_parent" 
     android:layout_height="match_parent" 
     android:gravity="top|center" 
     android:orientation="vertical"> 


     <ImageView 
      android:id="@+id/userPhotoImageView" 
      android:layout_width="match_parent" 
      android:layout_height="436dp" 
      /> 

     <LinearLayout 
      android:layout_width="wrap_content" 
      android:layout_height="wrap_content"> 

      <internetlegion.com.restaurantlunchify.Templates.MaterialRippleLayout 
       style="@style/RippleStyle" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_gravity="end" 
       android:layout_marginTop="54dp" 
       android:layout_marginRight="20dp" 
       android:layout_marginEnd="20dp" 
       app:rippleColor="@color/main_color_grey_400"> 

       <internetlegion.com.restaurantlunchify.Templates.RobotoTextView 
        android:id="@+id/uploadUserImageButton" 
        style="@style/ButtonStyle.RaisedEmpty" 
        android:layout_width="wrap_content" 
        android:layout_height="wrap_content" 
        android:background="@color/main_color_900" 
        android:minWidth="112dp" 
        android:layout_marginRight="20dp" 
        android:layout_marginEnd="20dp" 
        android:text="Upload" 
        android:textColor="#fff" /> 
      </internetlegion.com.restaurantlunchify.Templates.MaterialRippleLayout> 

      <CheckBox 
       android:layout_width="80dp" 
       android:layout_height="wrap_content" 
       android:layout_marginTop="0dp" 
       android:layout_marginRight="0dp" 
       android:layout_marginEnd="0dp" 
       android:layout_gravity="center_horizontal" 
       android:text="Default" 
       android:id="@+id/profilePhotoCheckBox" 
       android:checked="false" /> 

      <internetlegion.com.restaurantlunchify.Templates.MaterialRippleLayout 
       style="@style/RippleStyle" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:layout_gravity="end" 
       android:layout_marginTop="54dp" 
       app:rippleColor="@color/main_color_grey_400"> 


      <internetlegion.com.restaurantlunchify.Templates.RobotoTextView 
       android:id="@+id/userPhotoButtonSelect" 
       style="@style/ButtonStyle.RaisedEmpty" 
       android:layout_width="wrap_content" 
       android:layout_height="wrap_content" 
       android:background="@color/main_color_900" 
       android:minWidth="112dp" 
       android:text="Capture" 
       android:textColor="#fff" /> 
      </internetlegion.com.restaurantlunchify.Templates.MaterialRippleLayout> 


     </LinearLayout> 



    </LinearLayout> 

    <ProgressBar 
     style="?android:attr/progressBarStyleLarge" 
     android:layout_width="wrap_content" 
     android:layout_height="wrap_content" 
     android:id="@+id/progressBar" 
     android:progressDrawable="@drawable/circular_progress_bar" 
     android:layout_below="@+id/button" 
     android:layout_alignRight="@+id/textView" 
     android:layout_alignEnd="@+id/textView" 
     android:layout_alignLeft="@+id/textview" 
     android:layout_alignStart="@+id/textview" 
     android:layout_alignParentBottom="true" /> 


    <ListView 
     android:id="@+id/restaurant_list_slidermenu" 
     android:layout_width="240dp" 
     android:layout_height="match_parent" 
     android:layout_gravity="start" 
     android:choiceMode="singleChoice" 
     android:dividerHeight="1dp" /> 

</android.support.v4.widget.DrawerLayout> 

图像是故意6MB左右，我正在上传到看到了吧，但它是不受待见。你能帮忙的话，我会很高兴。非常感谢。 :-)

Answer 1

在这个uploadImage(boolean profilePhoto)方法spinner.setVisibility(View.VISIBLE);和spinner.setVisibility(View.GONE);将被立即调用，因此你无法看到进度条。

理想情况下，你应该使用AsyncTask这样

class UploadImageAsyncTask extends AsyncTask<Void, Void, Void> { 

    @Override 
    protected void onPreExecute() { 
     super.onPreExecute(); 
     spinner.setVisibility(View.VISIBLE); 
    } 

    @Override 
    protected String doInBackground(Void... params) { 
     // Upload image here 
     return null; 
    } 

    @Override 
    protected void onPostExecute(String result) { 
     super.onPostExecute(result); 
     spinner.setVisibility(View.GONE); 
    } 
}