多个适配器更新列表项的通用 AsyncTask

Question

我是 Android 的新手，我有以下代码显示适配器中的项目列表。

我有四个不同的适配器，我正在调用一个命令 AsyncTask 来更新结果。我已经实现了一个 Interface ApiResponse 并覆盖 apiResponseProcessing() 以获得结果。

在列表项中 "Add to Cart" 每行添加了按钮。我向服务器请求的那个按钮的 OnClick。在该响应成功时，我想用 "Added To Cart".

更新按钮

我有问题如何更新 onBindViewHolder() 中绑定的字符串。 我在该方法中取得了成功，但不知道如何通过该方法更新单击的按钮。

这是我的适配器

/**
 * Adapter
 **/

public class AlbumPhotoDetailAdapter
        extends RecyclerView.Adapter<AlbumPhotoDetailAdapter.ViewHolder> implements ApiResponse {

    private final ArrayList<Photo> mValues;
    Album album;
    private Activity mContext;
    private int mMemberId;

    public AlbumPhotoDetailAdapter(Activity context, ArrayList<Photo> items) {
        mValues = items;
        this.mContext = context;
        mMemberId = MemberPreference.getMemberId(mContext);
    }

    @Override
    public ViewHolder onCreateViewHolder(ViewGroup parent, int viewType) {
        View view = LayoutInflater.from(parent.getContext())
                .inflate(R.layout.album_photo_detail_sub_view, parent, false);
        return new ViewHolder(view);
    }

    @Override
    public void onBindViewHolder(final ViewHolder holder, final int position) {
        final Photo photo = mValues.get(position);

        /**
         * Album Owner Name
         */
        String mOwnerName = photo.getOwnerName();
        String mOwnerProfilePic = photo.getOwnerImage();
        String mDateTime = photo.getDatetime();
        String mPrice = String.valueOf(photo.getPrice());

        /**
         * Price String
         */
        String priceStr = String.format(mContext.getString(R.string.string_dollar_price), mPrice);
        holder.mAlbumPhotoDetailPhotoPrice.setText(priceStr);

        /**
         * Main Image
         */
        Picasso.with(mContext).load(photo.getLink())
                .error(R.drawable.ic_place_holder_circle)
                .placeholder(R.drawable.ic_place_holder_circle)
                .transform(new ImageTransformation(holder.mAlbumPhotoDetailSubMainImage))
                .into(holder.mAlbumPhotoDetailSubMainImage);

        /**
         *  Owner Name and Profile Pic
         */
        holder.mAlbumPhotoDetailSubOwnerNameTextView.setText(mOwnerName);
        Picasso.with(mContext).load(mOwnerProfilePic)
                .error(R.drawable.ic_place_holder_circle)
                .placeholder(R.drawable.ic_place_holder_circle)
                .resize(100, 100)
                .transform(new CircleTransform())
                .into(holder.mAlbumPhotoDetailSubOwnerImage);

        mDateTime = mDateTime != null ? DateUtils.getNiceTime(mDateTime) : "----";
        holder.mAlbumPhotoDetailSubOwnerPostedTimeTextView.setText(mDateTime);       

        // Photo Add to cart.
        holder.mAddToCartButton.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                if(InternetConnection.checkConnection(mContext)) {
                    new BackgroundAsyncTask(mContext, (ApiResponse) mContext, mMemberId, photo.getId()).execute();
                } else {
                    DailyStudio.noInternetConnectionToast(mContext);
                }
            }
        });
    }


    @Override
    public int getItemCount() {
        return mValues.size();
    } 

    @Override
    public void apiResponseProcessing(String response) {
        Log.i(TAG,"Api Response : "+response);
        if(response.equals(Fields.JSON_SUCCESS)) {
        }
    }

    /**
     * View Holder
     */
    public static class ViewHolder extends RecyclerView.ViewHolder {

        public final View mView;

        private ImageView mAlbumPhotoDetailSubOwnerImage;
    private ImageView mAlbumPhotoDetailSubMainImage;
        private TextView mAlbumPhotoDetailSubOwnerNameTextView;
        private TextView mAlbumPhotoDetailSubOwnerPostedTimeTextView;     
        private TextView mAlbumPhotoDetailPhotoPrice;
        private TextView mAlbumPhotoDetailSubDescription;
        private Button mAddToCartButton;

        public ViewHolder(View view) {
            super(view);
            mView = view;

            mAlbumPhotoDetailSubOwnerImage = (ImageView) view.findViewById(R.id.album_photo_detail_sub_owner_image);
        mAlbumPhotoDetailSubMainImage = (ImageView) view.findViewById(R.id.album_photo_detail_sub_main_image);          
        mAlbumPhotoDetailSubOwnerNameTextView = (TextView) view.findViewById(R.id.album_photo_detail_sub_owner_name_text_view);
            mAlbumPhotoDetailSubOwnerPostedTimeTextView = (TextView) view.findViewById(R.id.album_photo_detail_sub_owner_posted_time_text_view);
            mAlbumPhotoDetailPhotoPrice = (TextView) view.findViewById(R.id.album_photo_detail_photo_price);
            mAlbumPhotoDetailSubDescription = (TextView) view.findViewById(R.id.album_photo_detail_sub_description);
            mAddToCartButton = (Button) view.findViewById(R.id.album_photo_detail_photo_add_to_cart_button);
        }
    }
}

这是我的界面

/**
* Interface..
*/

public interface ApiResponse {

    public void apiResponseProcessing(String response);

}

这是我的后台 AsyncTask

/**
* Background AsyncTask...
*/

public class BackgroundAsyncTask extends AsyncTask<Void, Void, String> {

    private Context context;
    private String accessToken;
    private int memberId;
    private int photoId;
    private ApiResponse objIBaseApi;

    public BackgroundAsyncTask(Context context, ApiResponse apiResponse, int memberId, int photoId) {
        this.context = context;
        this.memberId = memberId;
        this.photoId = photoId;
        accessToken = MemberPreference.getAccessToken(context);
        this.objIBaseApi = apiResponse;
    }

    @Override
    protected void onPreExecute() {
        super.onPreExecute();
    }

    @Override
    protected String doInBackground(Void... params) {

        JSONObject json = JSONParser.addToCartPhoto(accessToken, memberId, photoId);

        if(json != null) {
            Log.i(TAG,"First Json : "+json.toString());
            try {
                if (json.getString(Fields.RESULT).equalsIgnoreCase(Fields.JSON_SUCCESS)) {
                    return Fields.JSON_SUCCESS;
                } else if(json.getString(Fields.JSON_ERROR).equalsIgnoreCase(Fields.ERROR_ACCESS_DENIED)) {
                    String refreshToken = MemberPreference.getRefreshToken(context);

                    JSONObject newJSONObject = JSONParser.loginMemberWithRefreshToken(refreshToken, Integer.toString(memberId));

                    if(newJSONObject != null) {
                        if(newJSONObject.getString(Fields.JSON_ERROR).equalsIgnoreCase(Fields.ERROR_ACCESS_DENIED)) {
                            return Fields.ERROR_ACCESS_DENIED;
                        } else {
                            return Fields.JSON_SUCCESS;
                        }
                    } else
                        return Fields.ERROR_ACCESS_DENIED;

                } else {
                    return Fields.JSON_ERROR;
                }
            } catch (JSONException e) {
                e.printStackTrace();
                return Fields.JSON_ERROR;
            }
        }
        return Fields.JSON_ERROR;
    }

    @Override
    protected void onPostExecute(String result) {
        super.onPostExecute(result);

        objIBaseApi.apiResponseProcessing(result);

    }
}

是否有任何解决方案或更好的方法来做到这一点？

您的帮助将不胜感激。谢谢。

Answer 1

首先我认为适配器不应该关心网络请求。但实质上给出答案，您可以尝试以与为按钮创建 OnClickListener 相同的方式为您的 apiResponseProcessing 传递匿名 class。它可能看起来像这样：

holder.mAddToCartButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(InternetConnection.checkConnection(mContext)) {
                new BackgroundAsyncTask(
                    mContext, 
                    new ApiResponse() {
                        @Override
                        public void apiResponseProcessing(String response) {
                            Log.i(TAG,"Api Response : "+response);
                            if(response.equals(Fields.JSON_SUCCESS)) {
                                // Here you can access you holder till it final 
                            }
                        }
                    }, 
                    mMemberId, 
                    photo.getId()).execute();
            } else {
                DailyStudio.noInternetConnectionToast(mContext);
            }
        }
});

但是像这样的代码看起来很乱而且像意大利面条一样。正如我在开头所说，至少存在一种不同的方法来处理 listview/recivleview 中按钮的更改。我使用方法，其中适配器只关心使用给定数据构建界面并将按钮点击委托给其他人（在大多数情况下 activity 包含列表视图）。通知 activity 按钮点击的一种简单方法是总线消息传递模式。我使用 Otto event library。当委托收到按钮点击通知时，它可以根据当前任务启动数据更改，然后启动列表视图重新加载或部分更新所需的行。

补充评论

Try to write beautiful code. Constructor AlbumPhotoDetailAdapter has different syntax to assign instance variables. One with this keyword and other without. Usually you should use one way.

public AlbumPhotoDetailAdapter(Activity context, ArrayList<Photo> items) {
    this.values = items;
    this.context = context;
    this.memberId = MemberPreference.getMemberId(context);
}

album instance variable have no access modifiers indication. You should know, that in java programming language omitting access specifiers is not the same as private modifier.

Answer 2

您可以在适配器中使用的 bean class 中保留一个标志 isAddedToCart 变量（照片）。现在只需在用户单击 "add to cart" 按钮后传递异步任务中的位置。获得成功后，您只需要从传递给适配器的 bean 列表中找到 bean，并将标志 isAddedToCart 更改为 true 并通知您的适配器即可。这是代码片段：-

照片Class

public class Photo{
private boolean isAddedToCart;

public void setAddedTOCart(boolean isAdded){
   isAddedToCart = isAdded;
}
public boolean isAddedToCart(){
   return isAddedToCart;
}

}

AlbumPhotoDetailAdapter onBindViewHolder

@Override
public void onBindViewHolder(final ViewHolder holder, final int position) {
    final Photo photo = mValues.get(position);

    /**
     * Album Owner Name
     */
    String mOwnerName = photo.getOwnerName();
    String mOwnerProfilePic = photo.getOwnerImage();
    String mDateTime = photo.getDatetime();
    String mPrice = String.valueOf(photo.getPrice());
    String isAdded = photo.isAddedToCart();

    /**
     * Price String
     */
    String priceStr = String.format(mContext.getString(R.string.string_dollar_price), mPrice);
    holder.mAlbumPhotoDetailPhotoPrice.setText(priceStr);

    /**
     * Main Image
     */
    Picasso.with(mContext).load(photo.getLink())
            .error(R.drawable.ic_place_holder_circle)
            .placeholder(R.drawable.ic_place_holder_circle)
            .transform(new ImageTransformation(holder.mAlbumPhotoDetailSubMainImage))
            .into(holder.mAlbumPhotoDetailSubMainImage);

    /**
     *  Owner Name and Profile Pic
     */
    holder.mAlbumPhotoDetailSubOwnerNameTextView.setText(mOwnerName);
    Picasso.with(mContext).load(mOwnerProfilePic)
            .error(R.drawable.ic_place_holder_circle)
            .placeholder(R.drawable.ic_place_holder_circle)
            .resize(100, 100)
            .transform(new CircleTransform())
            .into(holder.mAlbumPhotoDetailSubOwnerImage);

    mDateTime = mDateTime != null ? DateUtils.getNiceTime(mDateTime) : "----";
    holder.mAlbumPhotoDetailSubOwnerPostedTimeTextView.setText(mDateTime);       
if(isAdded){
   holder.mAddToCartButton.setText("Added TO Cart");
}else{
   holder.mAddToCartButton.setText("Add TO Cart");    
}
    // Photo Add to cart.
    holder.mAddToCartButton.setOnClickListener(new View.OnClickListener() {
        @Override
        public void onClick(View v) {
            if(InternetConnection.checkConnection(mContext)) {
                new BackgroundAsyncTask(mContext, (ApiResponse) mContext, mMemberId, photo.getId(),position).execute();
            } else {
                DailyStudio.noInternetConnectionToast(mContext);
            }
        }
    });
}

你的界面

public interface ApiResponse {
     public void apiResponseProcessing(String response,int position);
}

你的适配器 apiResponceProcessing()

@Override
public void apiResponseProcessing(String response,int position) {
    Log.i(TAG,"Api Response : "+response);
    if(response.equals(Fields.JSON_SUCCESS)) {
        mValues.get(position).setAddedTOCart(true);
        notifyDataSetChange();
    }
}

最后是你的 BackgroundAsyncTask

public class BackgroundAsyncTask extends AsyncTask<Void, Void, String> {

private Context context;
private String accessToken;
private int memberId;
private int photoId; 
private int mPosition;
private ApiResponse objIBaseApi;

public BackgroundAsyncTask(Context context, ApiResponse apiResponse, int memberId, int photoId,int position) {
    this.context = context;
    this.memberId = memberId;
    this.photoId = photoId;
    accessToken = MemberPreference.getAccessToken(context);
    this.objIBaseApi = apiResponse;
    this.mPosition = position;
}

@Override
protected void onPreExecute() {
    super.onPreExecute();
}

@Override
protected String doInBackground(Void... params) {

    JSONObject json = JSONParser.addToCartPhoto(accessToken, memberId, photoId);

    if(json != null) {
        Log.i(TAG,"First Json : "+json.toString());
        try {
            if (json.getString(Fields.RESULT).equalsIgnoreCase(Fields.JSON_SUCCESS)) {
                return Fields.JSON_SUCCESS;
            } else if(json.getString(Fields.JSON_ERROR).equalsIgnoreCase(Fields.ERROR_ACCESS_DENIED)) {
                String refreshToken = MemberPreference.getRefreshToken(context);

                JSONObject newJSONObject = JSONParser.loginMemberWithRefreshToken(refreshToken, Integer.toString(memberId));

                if(newJSONObject != null) {
                    if(newJSONObject.getString(Fields.JSON_ERROR).equalsIgnoreCase(Fields.ERROR_ACCESS_DENIED)) {
                        return Fields.ERROR_ACCESS_DENIED;
                    } else {
                        return Fields.JSON_SUCCESS;
                    }
                } else
                    return Fields.ERROR_ACCESS_DENIED;

            } else {
                return Fields.JSON_ERROR;
            }
        } catch (JSONException e) {
            e.printStackTrace();
            return Fields.JSON_ERROR;
        }
    }
    return Fields.JSON_ERROR;
}

@Override
protected void onPostExecute(String result) {
    super.onPostExecute(result);

    objIBaseApi.apiResponseProcessing(result,mPosition);

}

}

多个适配器更新列表项的通用 AsyncTask

Common AsyncTask for Multiple Adapter Update List Item

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android-asynctask