java - 将 Json 解析为 Java 对象

Question

我对 Json 的经验非常少，我必须将复杂的 Json 解析为 Java 对象。

我尝试了多种方法但都没有成功...我正在获取我所在城市的 Json 格式的天气预报，我需要将该 Json 数据解析为 Java 对象。

杰森:

{"city":
 {"city_code":"ATAT10678",
  "name":"Wien",
  "url":"oesterreich/wien/ATAT10678.html",
  "credit":{"info":"In order to use the free weather data from wetter.com you HAVE TO display at least two out of three of the following possibilities: text, link, logo",
  "text":"Powered by wetter.com","link":"http://www.wetter.com",
  "logo":"Download at http://www.wetter.com/api/downloads/#logos"},
  "forecast":{
   "2014-08-24":{
    "w":"1",
    "tx":"20",
    "pc":"30",
    "06:00":{
     "w":"2",
     "tx":"16",
     "pc":"30",
     "tn":"15",
     "p":"5",
     "dhl":"2014-08-24 06:00",
     "ws":"19",
     "w_txt":"wolkig"},
    "11:00":{
     "w":"2",
     "tx":"18",
     "pc":"30",
     "tn":"16",
     "p":"6",
     "dhl":"2014-08-24 11:00",
     "ws":"20",
     "w_txt":"wolkig"},
    "17:00":{
     "w":"1",
     "tx":"20",
     "pc":"20",
     "tn":"16",
     "p":"6",
     "dhl":"2014-08-24 17:00",
     "ws":"12",
     "w_txt":"leicht bewölkt"},
    "23:00":{
     "w":"1",
     "tx":"16",
     "pc":"10",
     "tn":"13",
     "p":"6",
     "dhl":"2014-08-24 23:00",
     "ws":"7",
     "w_txt":"leicht bewölkt"},
    "tn":"15",
    "p":"24",
    "dhl":"2014-08-24 06:00",
    "ws":"14",
    "w_txt":"leicht bewölkt"},
   "2014-08-25":{"w":"2","tx":"22","pc":"30","06:00":{"w":"2","tx":"17","pc":"20","tn":"12","p":"5","dhl":"2014-08-25 06:00","ws":"5","w_txt":"wolkig"},"11:00":{"w":"2","tx":"21","pc":"30","tn":"17","p":"6","dhl":"2014-08-25 11:00","ws":"10","w_txt":"wolkig"},"17:00":{"w":"2","tx":"22","pc":"30","tn":"18","p":"6","dhl":"2014-08-25 17:00","ws":"11","w_txt":"wolkig"},"23:00":{"w":"3","tx":"18","pc":"30","tn":"16","p":"6","dhl":"2014-08-25 23:00","ws":"6","w_txt":"bedeckt"},"tn":"12","p":"24","dhl":"2014-08-25 06:00","ws":"8","w_txt":"wolkig"},"2014-08-26":{"w":"3","tx":"22","pc":"75","06:00":{"w":"3","tx":"17","pc":"75","tn":"15","p":"5","dhl":"2014-08-26 06:00","ws":"6","w_txt":"bedeckt"},"11:00":{"w":"61","tx":"21","pc":"75","tn":"17","p":"6","dhl":"2014-08-26 11:00","ws":"9","w_txt":"leichter Regen"},"17:00":{"w":"61","tx":"22","pc":"75","tn":"18","p":"6","dhl":"2014-08-26 17:00","ws":"9","w_txt":"leichter Regen"},"23:00":{"w":"3","tx":"18","pc":"75","tn":"17","p":"6","dhl":"2014-08-26 23:00","ws":"9","w_txt":"bedeckt"},"tn":"15","p":"24","dhl":"2014-08-26 06:00","ws":"8","w_txt":"bedeckt"}}}}

我不知道如何将其解析为对象..

非常感谢您的建议!

这是我的第一次试用..

        Gson gson = new Gson();
        JsonObject jsonObj = gson.fromJson(br, JsonObject.class);
        Map<String, LinkedTreeMap> map = new HashMap<String, LinkedTreeMap>();
        map = (Map<String, LinkedTreeMap>) gson.fromJson(jsonObj.toString(), map.getClass());

        LinkedTreeMap<String, LinkedTreeMap> tmp = new LinkedTreeMap<>();
        tmp = map.get("city");

        for(Map.Entry<String, LinkedTreeMap> e : tmp.entrySet()) {
            System.out.println("k: " + e.getKey());
        }

        LinkedTreeMap<String, LinkedTreeMap> tmp1 = new LinkedTreeMap<>();
        tmp1 = tmp.get("forecast");

        for(Map.Entry<String, LinkedTreeMap> e : tmp1.entrySet()) {
            System.out.println("k: " + e.getKey());
            LinkedTreeMap<String, LinkedTreeMap> values = e.getValue();
            for(Map.Entry<String, LinkedTreeMap> v : values.entrySet()) {

                System.out.println("k: " + v.getKey() + " v: " + v.getValue());
            }

        }

和一天的输出:

k: city_code
k: name
k: url
k: credit
k: forecast
k: 2014-08-25
k: w v: 2
k: tx v: 23
k: pc v: 90
k: 06:00 v: {w=2, tx=17, pc=20, tn=13, p=5, dhl=2014-08-25 06:00, ws=5, w_txt=wolkig}
k: 11:00 v: {w=2, tx=21, pc=20, tn=17, p=6, dhl=2014-08-25 11:00, ws=9, w_txt=wolkig}
k: 17:00 v: {w=2, tx=23, pc=30, tn=17, p=6, dhl=2014-08-25 17:00, ws=11, w_txt=wolkig}
k: 23:00 v: {w=3, tx=17, pc=90, tn=16, p=6, dhl=2014-08-25 23:00, ws=6, w_txt=bedeckt}
k: tn v: 13
k: p v: 24
k: dhl v: 2014-08-25 06:00
k: ws v: 8
k: w_txt v: wolkig

到目前为止一切顺利，但我如何获得 06:00、11:00、17:00 和 23:00(通用，因为时间可以更改)因为这是我需要的信息？

非常感谢BR 台风

Answer 1

这是一个使用 GSON 的例子

import com.google.gson.JsonElement;
import com.google.gson.JsonParser;
public class CodeChefTest1 {
    public static String json = "{\"balance\": 1000.21, \"num\":100, \"is_vip\":true, \"name\":\"foo\"}";
    public static void main(String[] args) {
        JsonElement ele = new JsonParser().parse(json);
        for(java.util.Map.Entry<String, JsonElement> entr : ele.getAsJsonObject().entrySet()){
            System.out.println(entr.getKey());
            System.out.println(entr.getValue());
        }
    }
}

您可以使用上面的代码并使用对 JSONElements 的检查(如 isJSONArray()、isJSONObject()、isJSONPrimitive() 等)在循环中运行它，并使用相同的策略执行适当的重新解析。

上面只是遍历 json 字符串并打印所有键值对。您可以对 json 字符串的日期部分执行相同的操作。