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我正在使用 wunderground 来获取有关我的 java web 应用程序的天气信息。经过一番搜索，我发现 Gson 似乎是一个不错的 json 解析器。

但是按照一些示例，我似乎无法弄清楚如何跳过根元素。这是一个预测 json请求的示例：

{
    "forecast" : {
        "simpleforecast" : {
            "forecastday" : [ {
                "avehumidity" : 61,
                "avewind" : {
                    "degrees" : 342,
                    "dir" : "NNW",
                    "kph" : 11,
                    "mph" : 7
                },
                "conditions" : "Clear",
                "date" : {
                    "ampm" : "PM",
                    "day" : 17,
                    "epoch" : "1358478000",
                    "hour" : 21,
                    "isdst" : "0",
                    "min" : "00",
                    "month" : 1,
                    "monthname" : "January",
                    "pretty" : "9:00 PM CST on January 17, 2013",
                    "sec" : 0,
                    "tz_long" : "America/Chicago",
                    "tz_short" : "CST",
                    "weekday" : "Thursday",
                    "weekday_short" : "Thu",
                    "yday" : 16,
                    "year" : 2013
                },
                "high" : {
                    "celsius" : "11",
                    "fahrenheit" : "52"
                },
                "icon" : "clear",
                "icon_url" : "http://icons-ak.wxug.com/i/c/k/clear.gif",
                "low" : {
                    "celsius" : "-2",
                    "fahrenheit" : "28"
                },
                "maxhumidity" : 76,
                "maxwind" : {
                    "degrees" : 340,
                    "dir" : "NNW",
                    "kph" : 18,
                    "mph" : 11
                },
                "minhumidity" : 38,
                "period" : 1,
                "pop" : 10,
                "qpf_allday" : {
                    "in" : 0.0,
                    "mm" : 0.0
                },
                "qpf_day" : {
                    "in" : 0.0,
                    "mm" : 0.0
                },
                "qpf_night" : {
                    "in" : 0.0,
                    "mm" : 0.0
                },
                "skyicon" : "mostlysunny",
                "snow_allday" : {
                    "cm" : 0,
                    "in" : 0
                },
                "snow_day" : {
                    "cm" : 0,
                    "in" : 0
                },
                "snow_night" : {
                    "cm" : 0,
                    "in" : 0
                }
            },
            {
                "avehumidity" : 59,
                "avewind" : {
                    "degrees" : 172,
                    "dir" : "South",
                    "kph" : 6,
                    "mph" : 4
                },
                "conditions" : "Clear",
                "date" : {
                    "ampm" : "PM",
                    "day" : 18,
                    "epoch" : "1358564400",
                    "hour" : 21,
                    "isdst" : "0",
                    "min" : "00",
                    "month" : 1,
                    "monthname" : "January",
                    "pretty" : "9:00 PM CST on January 18, 2013",
                    "sec" : 0,
                    "tz_long" : "America/Chicago",
                    "tz_short" : "CST",
                    "weekday" : "Friday",
                    "weekday_short" : "Fri",
                    "yday" : 17,
                    "year" : 2013
                },
                "high" : {
                    "celsius" : "10",
                    "fahrenheit" : "50"
                },
                "icon" : "clear",
                "icon_url" : "http://icons-ak.wxug.com/i/c/k/clear.gif",
                "low" : {
                    "celsius" : "-1",
                    "fahrenheit" : "30"
                },
                "maxhumidity" : 84,
                "maxwind" : {
                    "degrees" : 170,
                    "dir" : "South",
                    "kph" : 10,
                    "mph" : 6
                },
                "minhumidity" : 40,
                "period" : 2,
                "pop" : 0,
                "qpf_allday" : {
                    "in" : 0.0,
                    "mm" : 0.0
                }, ..................

现在我只感兴趣的部分是forecastday。所以我做的是以下内容：

package entity.json;

import java.util.List;

public class Data {
    private List<Forecast> forecastday;

    public List<Forecast> getForecastdays() {
        return forecastday;
    }
}

预测类：

package entity.json;

public class Forecast {
    private int avehumidity;
    private Avewind avewind;
    private String conditions;
    private DateWeather date;
    private CelciusHigh high;
    private String icon_url;
    private CelciusLow low;
    // + constructor, getters, setters

这是我的方法：

public void createWeatherForecast(){
        String text = "";
        try {
            URL url = new URL(jsonUrl);
            System.out.println(jsonUrl);
            Scanner s = new Scanner(url.openStream());
            while(s.hasNextLine()){
                text += s.nextLine();
            }
            Data weather = new Gson().fromJson(text, Data.class);
            System.out.println(new Gson().toJson(weather));
            System.out.println(weather.getForecastdays().get(0).getAvewind());
        } catch (IOException ex) {
            Logger.getLogger(WeatherController.class.getName()).log(Level.SEVERE, null, ex);
        }
    }

现在我也应该专注于预测和简单预测吗？

4

1 回答 1

1

仅仅因为你对 JSON 对象的一部分“只感兴趣”并不能使 Gson 神奇地提供它；）

您要么需要使 POJO 匹配 JSON 对象，要么编写自定义反序列化器，丢弃您不感兴趣的 JSON 对象部分并返回您的Data类的实例。

于 2013-01-18T14:46:34.620 回答