片段中的 Asynctask 未到达 onPostExecute
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【中文标题】片段中的 Asynctask 未到达 onPostExecute【英文标题】：Asynctask in fragment is not getting to onPostExecute 【发布时间】：2019-01-25 19:21:21 【问题描述】：我正在使用 openweathermap api（5 天预报），并且正在使用 GSON 解析数据。 asynctask 与服务器连接，但它不去 onPostExecute。它在收到响应 200 代码后终止。我认为它设置正确，但没有完成程序：
private static class GetWeatherAync extends AsyncTask<Context, Void, List<ForecastWeatherList>>
private String TAG = GetWeatherAync.class.getSimpleName();
private final String serviceUrl;
private Context mContext;
private Listener listener;
HttpURLConnection urlConnection = null;
public GetWeatherAync(Listener listener, Object mStatusView, Object api_key)
this.listener = listener;
this.serviceUrl = "http://api.openweathermap.org/data/2.5/forecast?q=" + "Baltimore" + api_key;
@Override
protected List<ForecastWeatherList> doInBackground(Context...params)
try
Log.d("debugMode", "The application is in doInBackground");
URL url = new URL(serviceUrl);
urlConnection = (HttpURLConnection) url.openConnection();
urlConnection.setReadTimeout(10000 /* milliseconds */);
urlConnection.setConnectTimeout(15000 /* milliseconds */);
urlConnection.setRequestMethod("GET");
urlConnection.connect();
// If the request was successful (response code 200),
// then read the input stream and parse the response.
if (urlConnection.getResponseCode() == 200)
Log.e(TAG,"Response code:" + urlConnection.getResponseCode());
BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream()));
ForecastWeatherListWrapper weatherWrapper = new Gson().fromJson(bufferedReader, ForecastWeatherListWrapper.class);
return weatherWrapper.getforecastWeatherLists();
else
Log.e(TAG, "Error response code: " + urlConnection.getResponseCode());
catch (Exception e)
return null;
@Override
protected void onPostExecute(List<ForecastWeatherList> result)
super.onPostExecute(result);
if (result != null)
Log.e(TAG, "populate UI recycler view with gson converted data");
listener.afterSearch(result);
这是我的日志： E/GetWeatherAync：响应代码：200
这是我的预报天气列表包装器：
public class ForecastWeatherListWrapper
@SerializedName("list")
@Expose
private List<ForecastWeatherList> forecastWeatherLists;
public List<ForecastWeatherList> getforecastWeatherLists()
return forecastWeatherLists;
public void setforecastWeatherLists(List<ForecastWeatherList>
forecastWeatherItems)
this.forecastWeatherLists = forecastWeatherItems;
public class ForecastWeatherList
@SerializedName("dt")
@Expose
private Integer dt;
@SerializedName("main")
@Expose
private Main main;
@SerializedName("weather")
@Expose
private Weather weather = null;
@SerializedName("clouds")
@Expose
private Clouds clouds;
@SerializedName("wind")
@Expose
private Wind wind;
@SerializedName("rain")
@Expose
private Rain rain;
@SerializedName("sys")
@Expose
private Sys sys;
@SerializedName("dt_txt")
@Expose
private String dtTxt;
public Integer getDt()
return dt;
public void setDt(Integer dt)
this.dt = dt;
public Main getMain()
return main;
public void setMain(Main main)
this.main = main;
public Weather getWeather()
return (Weather) weather;
public void setWeather(Weather weather)
this.weather = weather;
public Clouds getClouds()
return clouds;
public void setClouds(Clouds clouds)
this.clouds = clouds;
public Wind getWind()
return wind;
public void setWind(Wind wind)
this.wind = wind;
public Rain getRain()
return rain;
public void setRain(Rain rain)
this.rain = rain;
public Sys getSys()
return sys;
public void setSys(Sys sys)
this.sys = sys;
public String getDtTxt()
return dtTxt;
public void setDtTxt(String dtTxt)
this.dtTxt = dtTxt;
这是我的一些用于解析 JSON 数据的 GSON 类。一些类是 Main、Clouds 等
这是我的主要课程：
public class Main
@SerializedName("temp")
@Expose
private Double temp;
@SerializedName("temp_min")
@Expose
private Double tempMin;
@SerializedName("temp_max")
@Expose
private Double tempMax;
@SerializedName("pressure")
@Expose
private Double pressure;
@SerializedName("sea_level")
@Expose
private Double seaLevel;
@SerializedName("grnd_level")
@Expose
private Double grndLevel;
@SerializedName("humidity")
@Expose
private Integer humidity;
@SerializedName("temp_kf")
@Expose
private Integer tempKf;
public Double getTemp()
return temp;
public void setTemp(Double temp)
this.temp = temp;
public Double getTempMin()
return tempMin;
public void setTempMin(Double tempMin)
this.tempMin = tempMin;
public Double getTempMax()
return tempMax;
public void setTempMax(Double tempMax)
this.tempMax = tempMax;
public Double getPressure()
return pressure;
public void setPressure(Double pressure)
this.pressure = pressure;
public Double getSeaLevel()
return seaLevel;
public void setSeaLevel(Double seaLevel)
this.seaLevel = seaLevel;
public Double getGrndLevel()
return grndLevel;
public void setGrndLevel(Double grndLevel)
this.grndLevel = grndLevel;
public Integer getHumidity()
return humidity;
public void setHumidity(Integer humidity)
this.humidity = humidity;
public Integer getTempKf()
return tempKf;
public void setTempKf(Integer tempKf)
this.tempKf = tempKf;
这是我的天气课：
public class Weather
@SerializedName("id")
@Expose
private Integer id;
@SerializedName("main")
@Expose
private String main;
@SerializedName("description")
@Expose
private String description;
@SerializedName("icon")
@Expose
private String icon;
public Integer getId()
return id;
public void setId(Integer id)
this.id = id;
public String getMain()
return main;
public void setMain(String main)
this.main = main;
public String getDescription()
return description;
public void setDescription(String description)
this.description = description;
public String getIcon()
return icon;
public void setIcon(String icon)
this.icon = icon;
这是我的原始字符串数据（我认为）。
"cod":"200",
"message":0.0074,
"cnt":39,
"list":[
"dt":1534215600,
"main":
"temp":293.24,
"temp_min":292.346,
"temp_max":293.24,
"pressure":1021.77,
"sea_level":1028.21,
"grnd_level":1021.77,
"humidity":100,
"temp_kf":0.89
,
"weather":[
"id":500,
"main":"Rain",
"description":"light rain",
"icon":"10n"
],
"clouds":
"all":20
,
"wind":
"speed":2.51,
"deg":275.001
,
"rain":
"3h":0.0050000000000008
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-14 03:00:00"
,
"dt":1534226400,
"main":
"temp":292.3,
"temp_min":291.706,
"temp_max":292.3,
"pressure":1020.99,
"sea_level":1027.42,
"grnd_level":1020.99,
"humidity":100,
"temp_kf":0.6
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01n"
],
"clouds":
"all":0
,
"wind":
"speed":2.52,
"deg":294.505
,
"rain":
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-14 06:00:00"
,
"dt":1534237200,
"main":
"temp":291.07,
"temp_min":290.77,
"temp_max":291.07,
"pressure":1020.65,
"sea_level":1027.03,
"grnd_level":1020.65,
"humidity":100,
"temp_kf":0.3
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01n"
],
"clouds":
"all":0
,
"wind":
"speed":1.31,
"deg":225.5
,
"rain":
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-14 09:00:00"
,
"dt":1534248000,
"main":
"temp":293.286,
"temp_min":293.286,
"temp_max":293.286,
"pressure":1020.78,
"sea_level":1027.17,
"grnd_level":1020.78,
"humidity":100,
"temp_kf":0
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"02d"
],
"clouds":
"all":8
,
"wind":
"speed":2.83,
"deg":234.501
,
"rain":
,
"sys":
"pod":"d"
,
"dt_txt":"2018-08-14 12:00:00"
,
"dt":1534258800,
"main":
"temp":298.671,
"temp_min":298.671,
"temp_max":298.671,
"pressure":1020.76,
"sea_level":1027.15,
"grnd_level":1020.76,
"humidity":92,
"temp_kf":0
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01d"
],
"clouds":
"all":0
,
"wind":
"speed":2.71,
"deg":259.5
,
"rain":
,
"sys":
"pod":"d"
,
"dt_txt":"2018-08-14 15:00:00"
,
"dt":1534269600,
"main":
"temp":300.7,
"temp_min":300.7,
"temp_max":300.7,
"pressure":1019.76,
"sea_level":1026.18,
"grnd_level":1019.76,
"humidity":83,
"temp_kf":0
,
"weather":[
"id":500,
"main":"Rain",
"description":"light rain",
"icon":"10d"
],
"clouds":
"all":24
,
"wind":
"speed":3.66,
"deg":285.503
,
"rain":
"3h":1.11
,
"sys":
"pod":"d"
,
"dt_txt":"2018-08-14 18:00:00"
,
"dt":1534280400,
"main":
"temp":298.464,
"temp_min":298.464,
"temp_max":298.464,
"pressure":1019.68,
"sea_level":1025.97,
"grnd_level":1019.68,
"humidity":83,
"temp_kf":0
,
"weather":[
"id":500,
"main":"Rain",
"description":"light rain",
"icon":"10d"
],
"clouds":
"all":48
,
"wind":
"speed":3.27,
"deg":289.504
,
"rain":
"3h":1.61
,
"sys":
"pod":"d"
,
"dt_txt":"2018-08-14 21:00:00"
,
"dt":1534291200,
"main":
"temp":297.882,
"temp_min":297.882,
"temp_max":297.882,
"pressure":1020,
"sea_level":1026.37,
"grnd_level":1020,
"humidity":82,
"temp_kf":0
,
"weather":[
"id":500,
"main":"Rain",
"description":"light rain",
"icon":"10n"
],
"clouds":
"all":36
,
"wind":
"speed":2.37,
"deg":275.004
,
"rain":
"3h":0.13
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-15 00:00:00"
,
"dt":1534302000,
"main":
"temp":295.242,
"temp_min":295.242,
"temp_max":295.242,
"pressure":1021.11,
"sea_level":1027.53,
"grnd_level":1021.11,
"humidity":94,
"temp_kf":0
,
"weather":[
"id":802,
"main":"Clouds",
"description":"scattered clouds",
"icon":"03n"
],
"clouds":
"all":32
,
"wind":
"speed":1.26,
"deg":313.002
,
"rain":
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-15 03:00:00"
,
"dt":1534312800,
"main":
"temp":294.05,
"temp_min":294.05,
"temp_max":294.05,
"pressure":1021.27,
"sea_level":1027.77,
"grnd_level":1021.27,
"humidity":100,
"temp_kf":0
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01n"
],
"clouds":
"all":0
,
"wind":
"speed":2.46,
"deg":274.504
,
"rain":
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-15 06:00:00"
,
"dt":1534323600,
"main":
"temp":293.495,
"temp_min":293.495,
"temp_max":293.495,
"pressure":1021.36,
"sea_level":1027.7,
"grnd_level":1021.36,
"humidity":100,
"temp_kf":0
,
"weather":[
"id":800,
"main":"Clear",
"description":"clear sky",
"icon":"01n"
],
"clouds":
"all":0
,
"wind":
"speed":3.01,
"deg":277.505
,
"rain":
,
"sys":
"pod":"n"
,
"dt_txt":"2018-08-15 09:00:00"
],
"city":
"id":4347778,
"name":"Baltimore",
"coord":
"lat":39.2909,
"lon":-76.6108
,
"country":"US",
"population":620961
【问题讨论】：
或者这段代码返回 nullreturn weatherWrapper.getforecastWeatherLists();?
【参考方案1】：
可能在您打印日志后，当您尝试转换 JSON 对象尝试在返回值之前打印日志时发生异常
Log.e("something",weatherWrapper.getforecastWeatherLists().size()+"")
return weatherWrapper.getforecastWeatherLists();
很可能你有 JSON 转换异常
尝试登录catch看看发生了什么
catch (Exception e)
Log.e("catch","error")
【讨论】：
@ksb 请打印异常信息 这是我收到的异常消息：java.lang.IllegalStateException: Expected BEGIN_OBJECT but was BEGIN_ARRAY at line 1 column 224 path $.list[0].weather @ksb 请告诉我你的 ForecastWeatherListWrapper 类也记录这个 BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream())); Log.e("response",bufferedReader.toString) 我刚刚将包装代码添加到我原来的帖子的主体中。 请在 bufferedReader = new BufferedReader(new InputStreamReader(urlConnection.getInputStream())) 之后添加 Log.e("response",bufferedReader.toString);【参考方案2】：我认为问题出在您的网址上。你需要传递这样的参数，你忘记传递appid了吗？ -
https://samples.openweathermap.org/data/2.5/forecast?q=London,us&mode=xml&appid=b6907d289e10d714a6e88b30761fae22
您确定从 URL 获得正确的响应吗？如果是，请检查您的 AsyncTask 是否返回 null
@Override
protected void onPostExecute(List<ForecastWeatherList> result)
super.onPostExecute(result);
if (result != null)
Log.e(TAG, "populate UI recycler view with gson converted data");
listener.afterSearch(result);
else
Log.e(TAG, "Result is null");
// check if this Log shows up?
更改您的服务网址
this.serviceUrl = "http://api.openweathermap.org/data/2.5/forecast?q=" + "巴尔的摩" +"&appid="+api_key
【讨论】：
是的，我刚刚查过了。我的 logcat 中出现“结果为空”。【参考方案3】：您的回复中的错误。 你的代码
ForecastWeatherListWrapper weatherWrapper = new Gson().fromJson(bufferedReader, ForecastWeatherListWrapper.class);
将响应转换为自定义对象。 所以响应必须以“”开头 但是您的响应以数组“[”
开头您必须修复您的响应或使您的自定义对象期望像这样的数组
Gson gson = new Gson();
Type type = new TypeToken<List<ForecastWeatherListWrapper>>()
.getType();
if (!bufferedReader.equals(""))
ForecastWeatherListWrapper weatherWrapper = gson.fromJson(bufferedReader, type);
【讨论】：
谢谢，但现在我得到：java.lang.IllegalStateException: Expected BEGIN_ARRAY but was BEGIN_OBJECT at line 1 column 2 path $ 你可以打印你的响应和 ForecastWeatherListWrapper 类你可以使用 POSTMAN 来读取响应以上是关于片段中的 Asynctask 未到达 onPostExecute的主要内容，如果未能解决你的问题，请参考以下文章
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