如何将JSON元素标签设置为ListView? [英] How to set JSON element tag into ListView?

问题描述

我有这个JSON文件，我必须通过单击以在WebView中打开url值，将标记"info"的每个值放入ListView中.使用"title" JSON标签的值设置ActionBar标题.

I have this JSON file and I must put each value of tag "info" into a ListView with click to open the url value in a WebView. The ActionBar title is set with value of the "title" JSON tag.

{
"mobiledata": {
    "geoJson_1": "http://###.###.###",
    "geoJson_2": "",
    "info": [
        {
            "title": "Italia",
            "uri": "https://mysite.wordpress.com/i/"
        },
        {
            "title": "Il tempo",
            "uri": "https://mysite.wordpress.com/il/"
        },
        {
            "title": "Le info",
            "uri": "https://mysite.wordpress.com/la-terra/"
        },
        {
            "title": "Il rischio",
            "uri": "https://mysite.wordpress.com/italia/regioni-italiane/"
        },
        {
            "title": "Le Rubriche mensili",
            "uri": "https://mysite.wordpress.com/tag/rubricamensile/"
        }
    ]
}

}

我该怎么做?有帮助或示例吗?

How can I do this? Any help or examples?

推荐答案

更新

旧答案中给出的方法太冗长.改善步骤:

Update

Approach given in old answer is too verbose. Steps to improve:

1. 使用Gson库，它既快速又紧凑.添加到您的模块级build.gradle文件中:

1. Use Gson library, it's fast and compact. Add into your module-level build.gradle file:

dependencies {
    // your dependencies: AppCompat, HTTP client etc
    compile 'com.google.code.gson:gson:2.7'
}

声明适当的数据结构:

Declare appropriate data structure:

class InfoItem {
    String title;
    String uri;
}

解析数据:

Parse data:

JsonElement data = new JsonParser().parse(json);

获取mobiledata.info:

Get mobiledata.info:

JsonArray info = data
        .getAsJsonObject() // treat parsed data as map
        .getAsJsonObject("mobiledata") // get 'mobiledata' as map
        .getAsJsonArray("info"); // get 'info' as list

将已解析的jsonObject映射到POJO

map parsed jsonObjects into POJOs

List<InfoItem> items = new Gson()
        .fromJson(info, new TypeToken<List<InfoItem>>(){}.getType());

使用您自己的适配器.使用ViewHolder时，模式绑定将如下所示:

Use your own adapter. With ViewHolder pattern binding will look like this:

InfoItem item = items.get(position);
holder.title.setText(item.title);
holder.uri.setText(item.uri);

P. S.您可能会缓存此丑陋的TypeToken:

P. S. You may cache this ugly TypeToken:

    private static final Type type = 
            new TypeToken<List<InfoItem>>(){}.getType();

要测试的完整代码:

    public class SoJsonAnswer {

        private static final Type type = 
                new TypeToken<List<InfoItem>>(){}.getType();

        public static void main(String[] args) {
            String json = "{paste it here}";
            JsonElement data = new JsonParser().parse(json);

            JsonArray info = data
                    .getAsJsonObject() // treat parsed data as map
                    .getAsJsonObject("mobiledata") // get map
                    .getAsJsonArray("info"); // get list

            // map parsed jsonObjects into POJOs
            List<InfoItem> items = new Gson().fromJson(info, type);

            System.out.println(items);
        }

    }

    class InfoItem {
        String title;
        String uri;

        @Override
        public String toString() {
            return "title=" + title + ", uri=" + uri;
        }
    }

原始答案

1. 在您的项目中包含一个JSON库. 我使用以下代码: https://code.google.com/p/json-simple /downloads/list

1. Include a JSON library in your project. I use this: https://code.google.com/p/json-simple/downloads/list

解析为对象.

String json = "{...}"; //Your JSON here
JSONParser parser = new JSONParser(); //Can cause ParseException
JSONObject obj = (JSONObject) parser.parse(json); //Can cause ClassCastException

获取内部数据.

Get inner data.

JSONObject mobileData = (JSONObject) obj.get("mobiledata");
JSONArray info = (JSONArray) mobileData.get("info");

将此数据打包到ArrayList中.只需使用for循环，将get您的物品投放到String.

Pack this data into an ArrayList. Just use for cycle, get your items and cast them to String.

ArrayList<Map<String, Object>> data = new ArrayList<>(info.size());
Map<String, Object> m;
JSONObject current;
for (int i = 0; i < info.size(); i++) {
  m = new HashMap<String, Object>();
  current = (JSONObject) info.get(i);

  m.put("title", (String) current.get("title"));
  m.put("url", (String) current.get("url"));
  data.add(m);
}

为ListView设置Adapter.

String[] from = { "title", "url" };
int[] to = { android.R.id.text1, android.R.id.text2 };

SimpleAdapter adapter = new SimpleAdapter(this, data, android.R.layout.simple_list_item_2,
from, to);
lvList.setAdapter(adapter);

希望它会有所帮助. 代码未经测试.

Hope it helps. Code not tested.

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