Question

我使用volley来解析来自newsAPI.org的新闻数据。我想将响应保存到Firebase以供离线查看和持久化。

这是来自API的示例回复：

articles: [
{
     author: "Megan Rose Dickey",
     title: "Ojo wants to be the electric scooter for commuters, but...",
     description: "Commuting in a busy city like San Francisco can be 
     annoying..",
     url: "https://techcrunch.com/2017/08/23/ojo-wants-to-be-the-electric-
     scooter-for-commuters-but-its-not-there-yet/",
     urlToImage: "https://img.vidible.tv/prod/2017",
     publishedAt: "2017-08-23T21:19:56Z"
},
{
     author: "Katie Roof",
     title: "Pishevar intervenes in Benchmark-Kalanick lawsuit",
     description: "Early Uber investor and former board member Shervin 
     Pishevar is speaking out against Benchmark again..",
     url: "https://techcrunch.com/2017/08/24/pishevar-sends-another-letter-
     to-uber-board-about-benchmark/",
     urlToImage:"https://tctechcrunch2011.files.wordpress.com/",
     publishedAt: "2017-08-24T22:49:59Z"
},

总共我在articles数组中有5个对象。我想将每个对象存储在Firebase数据库中。这就是我的尝试：

StringRequest stringRequest = new StringRequest(Request.Method.GET, Constants.NEWS_ENDPOINT,
            new Response.Listener<String>() {
                @Override
                public void onResponse(String response) {
                    if (response != null){
                        Log.d(TAG, "News Api Response is: \t" + response.toString());
                        try {
                            JSONObject jsonObject = new JSONObject(response);
                            JSONArray articles = jsonObject.getJSONArray("articles");
                            for (int i = 0; i < articles.length(); i++){
                                JSONObject items = articles.getJSONObject(i);

                                final String title_news = items.getString("title");
                                final String desc_news = items.getString("description");
                                final String urlImg = items.getString("urlToImage");
                                final String author_news = items.getString("author");
                                final String url = items.getString("url");
                                final String publishedAt = items.getString("publishedAt");

                                NewsItem newsItem = new NewsItem(author_news, title_news, desc_news, url, urlImg, publishedAt);
                                itemList.add(newsItem);

                                /**
                                 *  Save JSON Results to Firebase
                                 * */

                                for (int k = 0; k < articles.length(); k++){
                                    HashMap hashMap = new HashMap();

                                    hashMap.put("newsTitle", title_news);
                                    hashMap.put("newsDesc", desc_news);
                                    hashMap.put("newsImageUrl", urlImg);
                                    hashMap.put("newsAuthor", author_news);
                                    hashMap.put("newsUrl", url);
                                    hashMap.put("newsDate", publishedAt);

                                    newsRootRef.setValue(hashMap);
                                }

当我检查控制台时，它只保存一个对象，最后一个对象如下：

我希望将所有对象AS-IS存储在响应数组中，然后再检索它们。还有另一种方法吗？谢谢，抱歉这篇长篇文章。

Answer 1

在这种情况下，您需要使用push（）来存储数据。否则，您只是在每次迭代时替换引用处的数据。这就是为什么似乎只存储最后一条记录的原因。尝试更改此行：

newsRootRef.setValue(hashMap);

......进入这个：

newsRootRef.push().setValue(hashMap);

为避免重复条目，我建议您从Firebase中获取所有条目，并在HashSet中缓存url属性（因为此属性似乎是唯一的）。然后你可以修改你的代码：

if (!urlSet.contains(url)) {
    HashMap hashMap = new HashMap();
    hashMap.put("newsTitle", title_news);
    hashMap.put("newsDesc", desc_news);
    hashMap.put("newsImageUrl", urlImg);
    hashMap.put("newsAuthor", author_news);
    hashMap.put("newsUrl", url);
    hashMap.put("newsDate", publishedAt);
    newsRootRef.push(),setValue(hashMap);
}

但是当然你需要首先填充你的HashSet所以我建议做这样的事情：

    final Set<String> urlSet = new HashSet<>();

    newsRootRef.addChildEventListener(new ChildEventListener() {
        int i = 0;

        @Override
        public void onChildAdded(DataSnapshot dataSnapshot, String s) {

            urlSet.add(dataSnapshot.getValue(String.class));
            if (i++ == dataSnapshot.getChildrenCount()) {

                ...
                ...your code...
                StringRequest stringRequest = new StringRequest(Request.Method.GET, Constants.NEWS_ENDPOINT,
                        new Response.Listener<String>() {
                            @Override
                            public void onResponse(String response) {

                ...
                ...

            }

        }

        @Override
        public void onChildChanged(DataSnapshot dataSnapshot, String s) {
        }

        @Override
        public void onChildRemoved(DataSnapshot dataSnapshot) {
        }

        @Override
        public void onChildMoved(DataSnapshot dataSnapshot, String s) {
        }

        @Override
        public void onCancelled(DatabaseError databaseError) {
        }
    });

从Firebase中的NewsAPI存储JSON数组

1 个答案: