Question

我是Android开发的初学者。我已将此库用于http请求https://github.com/loopj/android-async-http。

然后我在GridView中渲染响应JSON需要很长时间。我使用进度对话框作为预加载器，但在呈现listview之前已将其删除。我怎么能解决这个问题？谢谢。

以下是此GridView的屏幕截图。

以下是此活动的实施。

public class LikesActivity extends BottomBarActivity //some custom activity {
List<Anticafe> mAnticafes = new ArrayList<>();
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_likes);

        /*some code*/



        Request.post(Constants.POST_SEARCH_API_LINK, params, new AsyncHttpResponseHandler() {
                @Override
                public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
                    Gson gson = new GsonBuilder().create();
                    Request request = gson.fromJson(new String(responseBody), Request.class);

                    mAnticafes = request.getAnticafes();
                    renderListView()
                }

                @Override
                public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
                    hideProcessDialog();
                }
            });


    }

    private void renderListView() {
         GridView likesList = (GridView) findViewById(R.id.likes_list);
        AnticafeAdapter anticafeAdapter = new AnticafeAdapter(this, mAnticafes); 
        anticafeAdapter.setWidth(getWidth());
        likesList.setAdapter(anticafeAdapter);
    }
}

这是适配器的完整实现。

public class AnticafeAdapter extends BaseAdapter{

    public static final String TAG = "image-request";
    private Context mContext;
    private List<Anticafe> mAnticafes = new ArrayList<>();
    private Client mClient;
    private View mConvertView;
    private int mWidth;

    public AnticafeAdapter(Context context, List<Anticafe> anticafes) {
        mContext = context;
        mAnticafes = anticafes;
    }

    public void setWidth(int mWidth) {
        this.mWidth = (int) (mWidth / 4.7);
    }

    @Override
    public int getCount() {
        return mAnticafes.size();
    }

    @Override
    public Anticafe getItem(int position) {
        return mAnticafes.get(position);
    }

    @Override
    public long getItemId(int position) {
        return getItem(position).getId();
    }

    @Override
    public View getView(int position, View convertView, ViewGroup parent) {

        final Anticafe anticafe = getItem(position);
        mClient = AnticafeApplication.getInstanse().getClient();
        mConvertView = convertView;
        final ProgressDialog processDialog = new ProgressDialog(mContext);

        processDialog.setMessage("Информация обновляется. Пожалуйста, подождите.");

        if(mConvertView == null) {
            mConvertView = LayoutInflater.from(mContext).inflate(R.layout.adapter_popular, null);
        }

        ImageView cover = (ImageView) mConvertView.findViewById(R.id.cover);
        CircularImageView logo = (CircularImageView) mConvertView.findViewById(R.id.logo);
        final ImageView like = (ImageView) mConvertView.findViewById(R.id.like);
        final TextView likesCount = (TextView) mConvertView.findViewById(R.id.likes_count);
        TextView name = (TextView) mConvertView.findViewById(R.id.name);
        TextView price = (TextView) mConvertView.findViewById(R.id.price);

        if(mClient != null) {
            final boolean liked = mClient.containsLike(anticafe.getId());
            if(liked) {
                like.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_like));
            } else {
                like.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_unlike));
            }
        } else {
            like.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_unlike));
        }

        likesCount.setText(String.valueOf(anticafe.getTotalLikes()));
        name.setText(anticafe.getName());
        price.setText(anticafe.getPrices());

        Picasso.with(mContext).load(anticafe.getAttachment().getCover()).networkPolicy(NetworkPolicy.OFFLINE).into(cover);
        Picasso.with(mContext).load(anticafe.getAttachment().getLogo()).resize(mWidth, mWidth).into(logo);

        likeMechanism(anticafe, processDialog, like, likesCount);

        name.setOnClickListener(anticafeOpenActivityEvent(anticafe.getId()));
        price.setOnClickListener(anticafeOpenActivityEvent(anticafe.getId()));
        logo.setOnClickListener(anticafeOpenActivityEvent(anticafe.getId()));
        cover.setOnClickListener(anticafeOpenActivityEvent(anticafe.getId()));

        BottomBarActivity activity = (BottomBarActivity) this.mContext;
        activity.hideProcessDialog();

        return mConvertView;
    }

    private void likeMechanism(final Anticafe anticafe, final ProgressDialog processDialog, final ImageView like, final TextView likesCount) {
        like.setOnClickListener(new OnClickListener() {
            @Override
            public void onClick(View v) {

                if (mClient == null) {
                    AlertDialog.Builder builder = new AlertDialog.Builder(mContext);
                    builder.setTitle("Вы не авторизованы")
                            .setMessage("До тех пор, пока вы не пройдете авторизацию, вы не сможете пользоваться некоторым функционалом нашего приложение. Авторизация займет всего лишь пару минут.")
                            .setCancelable(false)
                            .setNegativeButton("Скрыть", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                }
                            })
                            .setPositiveButton("Авторизоваться", new DialogInterface.OnClickListener() {
                                @Override
                                public void onClick(DialogInterface dialog, int which) {
                                    Intent intent = new Intent(mContext, AuthActivity.class);
                                    mContext.startActivity(intent);
                                    Activity activity = ((Activity) mContext);
                                    activity.overridePendingTransition(R.anim.slide_in_left, R.anim.slide_in_right);
                                }
                            });

                    AlertDialog dialog = builder.create();
                    dialog.show();

                } else {

                    processDialog.show();

                    RequestParams params = new RequestParams();
                    params.add("anticafe_id", anticafe.getId() + "");
                    AuthedRequest.post(Constants.LIKE_API_LINK, params, new AsyncHttpResponseHandler() {
                        @Override
                        public void onSuccess(int statusCode, Header[] headers, byte[] responseBody) {
                            processDialog.hide();
                            Gson gson = new GsonBuilder().create();
                            try {
                                LikeResponse response = gson.fromJson(new String(responseBody, Constants.UTF_8), LikeResponse.class);
                                if (response.getLikeStatus().equals("unliked")) {
                                    like.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_unlike));
                                } else if (response.getLikeStatus().equals("liked")) {
                                    like.setImageDrawable(mContext.getResources().getDrawable(R.drawable.ic_like));
                                }
                                likesCount.setText(String.valueOf(response.getTotalLikes()));
                            } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                            } finally {
                                processDialog.hide();
                            }
                        }

                        @Override
                        public void onFailure(int statusCode, Header[] headers, byte[] responseBody, Throwable error) {
                            try {
                                Log.d("json", "onSuccess: " + new String(responseBody, Constants.UTF_8));
                            } catch (UnsupportedEncodingException e) {
                                e.printStackTrace();
                            } finally {
                                processDialog.hide();
                            }
                        }

                    });
                }
            }
        });
    }

    private OnClickListener anticafeOpenActivityEvent(final int id) {
        return new OnClickListener() {
            @Override
            public void onClick(View v) {
                Bundle bundle = new Bundle();
                bundle.putInt("entity_id", id);
                ((BottomBarActivity) mContext).openNewActivity(AnticafeActivity.class, bundle);
            }
        };
    }

    private static class LikeResponse {

        @SerializedName("status")
        @Expose
        private Integer status;
        @SerializedName("error")
        @Expose
        private Boolean error;
        @SerializedName("likeStatus")
        @Expose
        private String likeStatus;
        @SerializedName("totalLikes")
        @Expose
        private Integer totalLikes;

        public LikeResponse(Integer status, Boolean error, String likeStatus, Integer totalLikes) {
            this.status = status;
            this.error = error;
            this.likeStatus = likeStatus;
            this.totalLikes = totalLikes;
        }

        /**
         *
         * @return
         * The status
         */
        public Integer getStatus() {
            return status;
        }

        /**
         *
         * @param status
         * The status
         */
        public void setStatus(Integer status) {
            this.status = status;
        }

        /**
         *
         * @return
         * The error
         */
        public Boolean getError() {
            return error;
        }

        /**
         *
         * @param error
         * The error
         */
        public void setError(Boolean error) {
            this.error = error;
        }

        /**
         *
         * @return
         * The likeStatus
         */
        public String getLikeStatus() {
            return likeStatus;
        }

        /**
         *
         * @param likeStatus
         * The likeStatus
         */
        public void setLikeStatus(String likeStatus) {
            this.likeStatus = likeStatus;
        }

        /**
         *
         * @return
         * The totalLikes
         */
        public Integer getTotalLikes() {
            return totalLikes;
        }

        /**
         *
         * @param totalLikes
         * The totalLikes
         */
        public void setTotalLikes(Integer totalLikes) {
            this.totalLikes = totalLikes;
        }

    }
}

Answer 1

你没有显示任何代码来确切地说出你的问题但无论如何最好使用第三方库来加载来自网络的图像，例如毕加索：
http://square.github.io/picasso
这个库可以平滑地加载您的图像并自行管理缓存的更新：
其他选项是你不要在你的适配器类的getView方法中使用viewHolder设计模式在当前代码中，您在gridView的每个单元格中调用findViewById方法，但您必须首次调用它。要解决此问题，您应该使用viewHolder设计模式。

带有视图持有者的getView方法示例：

@Override public View getView(int position, View convertView, ViewGroup parent) { ViewHolderItem viewHolder; /* * The convertView argument is essentially a "ScrapView" as described is Lucas post * http://lucasr.org/2012/04/05/performance-tips-for-androids-listview/ * It will have a non-null value when ListView is asking you recycle the row layout. * So, when convertView is not null, you should simply update its contents instead of inflating a new row layout. */ if(convertView==null){ // inflate the layout LayoutInflater inflater = ((Activity) mContext).getLayoutInflater(); convertView = inflater.inflate(layoutResourceId, parent, false); // well set up the ViewHolder viewHolder = new ViewHolderItem(); viewHolder.textViewItem = (TextView) convertView.findViewById(R.id.textViewItem); // store the holder with the view. convertView.setTag(viewHolder); }else{ // we've just avoided calling findViewById() on resource everytime // just use the viewHolder viewHolder = (ViewHolderItem) convertView.getTag(); } // object item based on the position ObjectItem objectItem = data[position]; // assign values if the object is not null if(objectItem != null) { // get the TextView from the ViewHolder and then set the text (item name) and tag (item ID) values viewHolder.textViewItem.setText(objectItem.itemName); viewHolder.textViewItem.setTag(objectItem.itemId); } return convertView; }

View holder类的示例（在此类中定义视图元素）：

static class ViewHolderItem { TextView textViewItem; }

了解更多信息，请参阅：
https://www.javacodegeeks.com/2013/09/android-viewholder-pattern-example.html

GridView使用HTTP响应呈现很长时间

1 个答案: