java - 如何更新 RecyclerView 中的项目？

Question

我正在创建应用程序，我在其中提供了 Facebook 时间轴等功能，人们可以在其中更新他们的故事，任何用户都可以喜欢或评论故事。一切正常，但我面临的问题是，当任何用户更新故事时，更新故事的数据会保存在服务器上，但不会同时添加到回收 View 中。当用户返回并再次出现在时间轴屏幕上时，列表将得到更新。我该如何解决这个问题？

自定义适配器

public class TimeLineListAdapter extends RecyclerView.Adapter<TimeLineListAdapter.ViewHolder> {
    private List<TimeLineItem> timeLineItems;
    String message, storyId, token;
    private Context context;
    ImageLoader imageLoader = AppController.getInstance().getImageLoader();

    public TimeLineListAdapter(List<TimeLineItem> timeLineItems, Context context) {
        super();
        this.context = context;
        this.timeLineItems = timeLineItems;
    }

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

    @Override
    public void onBindViewHolder(ViewHolder holder, final int position) {

        //Getting the particular item from the list
        TimeLineItem item =  timeLineItems.get(position);

        if (item.getTotalLikes().equals("0")){
            holder.txtLike.setText("");
        }else {
            holder.txtLike.setText(item.getTotalLikes());
        }

        if (item.getTotalComment().equals("0")){
            holder.txtComment.setText("");
        }else {
            holder.txtComment.setText("("+item.getTotalComment()+")");
        }

        if (item.getIsLike() == 0){

        }else {
            holder.imageLike.setImageBitmap(null);
            holder.imageLike.setBackgroundResource(R.drawable.islike);
            holder.txtLike.setTextColor(Color.parseColor("#3498db"));
        }

        holder.name.setText(item.getName() + " " + item.getLname());


        /*Long.parseLong(item.getTimeStamp()),
                System.currentTimeMillis(), DateUtils.SECOND_IN_MILLIS);*/
        holder.timestamp.setText(item.getTimeStamp());

        // Chcek for empty status message
        if (!TextUtils.isEmpty(item.getStatus())) {
            holder.statusMsg.setText(item.getStatus());
            holder.statusMsg.setVisibility(View.VISIBLE);
        } else {
            // status is empty, remove from view
            holder.statusMsg.setVisibility(View.GONE);
        }

        // Checking for null feed url
        if (item.getUrl() != null) {
            holder.url.setText(Html.fromHtml("<a href=\"" + item.getUrl() + "\">"
                    + item.getUrl() + "</a> "));

            // Making url clickable
            holder.url.setMovementMethod(LinkMovementMethod.getInstance());
            holder.url.setVisibility(View.VISIBLE);
        } else {
            // url is null, remove from the view
            holder.url.setVisibility(View.GONE);
        }

        // user profile pic
        holder.profilePic.setImageUrl(item.getProfilePic(), imageLoader);

        // Feed image
        if (item.getImge() != null) {
            holder.feedImageView.setImageUrl(item.getImge(), imageLoader);
            holder.feedImageView.setVisibility(View.VISIBLE);
            holder.feedImageView
                    .setResponseObserver(new TimeLineImageView.ResponseObserver() {
                        @Override
                        public void onError() {
                        }

                        @Override
                        public void onSuccess() {
                        }
                    });
        } else {
            holder.feedImageView.setVisibility(View.GONE);
        }

        holder.txtComment.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {

                final TimeLineItem m = timeLineItems.get(position);
                String ide = String.valueOf(m.getId());

                Intent intent = new Intent(context, StoryDetailActivity.class);
                intent.putExtra("storyId",ide);
                context.startActivity(intent);
            }
        });

        holder.txtCommentLabel.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View view) {
                final TimeLineItem m = timeLineItems.get(position);
                String ide = String.valueOf(m.getId());

                Intent intent = new Intent(context, StoryDetailActivity.class);
                intent.putExtra("storyId",ide);
                context.startActivity(intent);
            }
        });


        holder.imageLike.setOnTouchListener(new View.OnTouchListener() {
            @Override
            public boolean onTouch(View view, MotionEvent motionEvent) {

                TimelineActivity t = new TimelineActivity();

                final TimeLineItem m = timeLineItems.get(position);
                String ide = String.valueOf(m.getId());

                likeStory(ide,t.token);

                return false;
            }
        });

    }

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

    class ViewHolder extends RecyclerView.ViewHolder{

        TextView name, timestamp, statusMsg, url, txtLike, txtComment, txtCommentLabel;
        NetworkImageView profilePic;
        TimeLineImageView feedImageView;
        ImageView imageLike;

        //Initializing Views
        public ViewHolder(View itemView) {
            super(itemView);
            name = (TextView) itemView.findViewById(R.id.name);
            timestamp = (TextView) itemView.findViewById(R.id.timestamp);
            statusMsg = (TextView) itemView.findViewById(R.id.txtStatusMsg);
            url = (TextView) itemView.findViewById(R.id.txtUrl);
            profilePic = (NetworkImageView) itemView.findViewById(R.id.profilePic);
            feedImageView = (TimeLineImageView) itemView.findViewById(R.id.feedImage1);
            imageLike = (ImageView) itemView.findViewById(R.id.imgLike);
            txtLike = (TextView) itemView.findViewById(R.id.txtLike);
            txtComment = (TextView) itemView.findViewById(R.id.txtComment);
            txtCommentLabel = (TextView) itemView.findViewById(R.id.txtCommentLabel);
        }
    }

    private void likeStory(final String story_id, final String token) {
        // Tag used to cancel the request
        String tag_string_req = "req_register";

        StringRequest strReq = new StringRequest(Request.Method.POST, AppConfig.likeStory, new Response.Listener<String>() {

            @Override
            public void onResponse(String response) {

                try {
                    JSONObject jObj = new JSONObject(response);
                    boolean error = jObj.getBoolean("status");
                    message = jObj.getString("message");
                    if (error) {

                    } else {

                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

            }
        }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(context, "Oops something went wrong...", Toast.LENGTH_LONG).show();
            }
        }) {

            @Override
            protected Map<String
                    , String> getParams() {
                // Posting params to register url
                Map<String, String> params = new HashMap<String, String>();
                params.put("my_token", token);
                params.put("story_id", story_id);

                return params;
            }

        };

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
    }

}

时间线 Activity

public void getTimeLineData(final String token, final String page) {


        String tag_string_req = "req_register";
        // making fresh volley request and getting json
        StringRequest strReq = new StringRequest(Request.Method.POST, AppConfig.timeline, new Response.Listener<String>() {

            @Override
            public void onResponse(String response) {
                VolleyLog.d(TAG, "Response: " + response.toString());
                if (response != null) {
                    try {
                        JSONObject jObj = new JSONObject(response);
                        boolean error = jObj.getBoolean("status");
                        String message = jObj.getString("message");
                        if (error) {
                            totalPages = jObj.getInt("totalPages");
                            pageCount = jObj.getInt("page");

                            int limit = jObj.getInt("limit");
                            parseJsonFeed(response);
                        }

                    } catch (Exception e) {

                    }

                }
            }
        }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
                VolleyLog.d(TAG, "Error: " + error.getMessage());
            }
        }) {

            @Override
            protected Map<String, String> getParams() {
                // Posting params to register url
                Map<String, String> params = new HashMap<String, String>();
                params.put("my_token", token);
                params.put("page", page);
                params.put("limit", "5");

                return params;
            }
        };

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(strReq, tag_string_req);

    }

    private void parseJsonFeed(String response) {
        try {
            JSONObject jsonObj = new JSONObject(response);
            JSONArray feedArray = jsonObj.getJSONArray("data");

            for (int i = 0; i < feedArray.length(); i++) {
                JSONObject feedObj = (JSONObject) feedArray.get(i);

                TimeLineItem item = new TimeLineItem();
                item.setId(feedObj.getInt("id"));
                item.setName(feedObj.getString("name"));
                item.setLname(feedObj.getString("lname"));

                // Image might be null sometimes
                String image = feedObj.isNull("image") ? null : feedObj
                        .getString("image");

                if (image.equals("")) {
                    item.setImge(image);
                } else {
                    item.setImge(AppConfig.storyPic + image);
                }

                item.setStatus(feedObj.getString("story_text"));
                item.setProfilePic(AppConfig.profilePic + feedObj.getString("profile_pic"));
                item.setTimeStamp(feedObj.getString("time_stamp"));
                item.setIsLike(feedObj.getInt("is_like"));
                item.setTotalLikes(feedObj.getString("total_likes"));
                item.setTotalComment(feedObj.getString("total_comments"));

                /*// url might be null sometimes
                String feedUrl = feedObj.isNull("url") ? null : feedObj
                        .getString("url");
                item.setUrl(feedUrl);*/

                timeLineItems.add(item);
            }

            // notify data changes to list adapater
            adapter.notifyDataSetChanged();


        } catch (JSONException e) {
            e.printStackTrace();
        }
    }

private void addStory(final String story_text, final String token, final String image) {
        // Tag used to cancel the request
        String tag_string_req = "req_register";

        pDialog.setMessage("Please wait ...");
        showDialog();

        StringRequest strReq = new StringRequest(Request.Method.POST, AppConfig.addStory, new Response.Listener<String>() {

            @Override
            public void onResponse(String response) {
                hideDialog();

                try {
                    JSONObject jObj = new JSONObject(response);
                    boolean error = jObj.getBoolean("status");
                    message = jObj.getString("message");
                    if (error) {
                        adapter.notifyDataSetChanged();
                        txtStatusBox.setText("");
                        imgImageUpload.setImageBitmap(null);
                        imgImageUpload.setBackgroundResource(R.drawable.image);
                        Toast.makeText(TimelineActivity.this, message, Toast.LENGTH_SHORT).show();
                        slidingUpPanelLayout.setPanelState(SlidingUpPanelLayout.PanelState.COLLAPSED);

                    } else {

                        // Error occurred in registration. Get the error
                        // message
                        String errorMsg = jObj.getString("message");
                        Toast.makeText(TimelineActivity.this, errorMsg, Toast.LENGTH_LONG).show();
                    }
                } catch (JSONException e) {
                    e.printStackTrace();
                }

            }
        }, new Response.ErrorListener() {

            @Override
            public void onErrorResponse(VolleyError error) {
                Toast.makeText(TimelineActivity.this, "Oops something went wrong...", Toast.LENGTH_LONG).show();
                hideDialog();
            }
        }) {

            @Override
            protected Map<String
                    , String> getParams() {
                // Posting params to register url
                Map<String, String> params = new HashMap<String, String>();
                params.put("my_token", token);
                params.put("story_text", story_text);
                params.put("image", image);

                return params;
            }

        };

        // Adding request to request queue
        AppController.getInstance().addToRequestQueue(strReq, tag_string_req);
    }

Answer 1

你需要在服务器端实现某种轮询机制来做到这一点。有一个解决方法，但它不被认为是好的做法。您可以使用 Timer 定期调用 getTimeline 函数来更新回收器 View 。在你的 onCreate 中是这样的:

Timer autoRefresh;
autoRefresh=new Timer();
    autoRefresh.schedule(new TimerTask() {
        @Override
        public void run() {
            runOnUiThread(new Runnable() {
                public void run() {
                    getTimeLineData(token, page);
                }
            });
        }
    }, 0, your_time_in_milliseconds);

您甚至可以在 Android 中使用 AsyncTask 异步执行此操作。