如何解决将日期时间、日出和日落从毫秒转换为实时格式

我的天气应用以毫秒（即 1620792785）的形式显示来自 OpenWeatherMap 的日期时间（上次更新）、日出和日落数据。我正在尝试将其转换为实时格式（即 hh:mm a）。

我尝试在示例类中为 dt 使用此代码：

public String getPrettyDate() {
        SimpleDateFormat HMM = new SimpleDateFormat("hh:mm a",Locale.US);
        final Date date = new Date(dt*1000);
        return HMM.format(date);
    }

时间转换的很好，但是没有准确显示数据（这里是下午3点的时候，显示的是晚上9点）。

我也检查了这个网站是否有类似的问题，但没有发现。

所以我想：

准确转换 dt
准确转换日出和日落时间使用正确的代码和类。

编辑： 我的应用可以搜索任何城市，所以我不是针对特定时区而是针对所有城市

我的 JSON 响应：

{
   "coord":{
      "lon":-0.1257,"lat":51.5085
   },"weather":[
      {
         "id":804,"main":"Clouds","description":"overcast clouds","icon":"04d"
      }
   ],"base":"stations","main":{
      "temp":289.16,"feels_like":288.07,"temp_min":286.87,"temp_max":290.76,"pressure":1009,"humidity":48
   },"visibility":10000,"wind":{
      "speed":0.45,"deg":109,"gust":2.68
   },"clouds":{
      "all":100
   },"dt":1620830862,"sys":{
      "type":2,"id":2019646,"country":"GB","sunrise":1620792785,"sunset":1620848444
   },"timezone":3600,"id":2643743,"name":"London","cod":200
}

我的示例类：

public class Example {
    @Serializedname("coord")
    private Coord coord;
    @Serializedname("weather")
    private List<Weather> weather = null;
    @Serializedname("base")
    private String base;
    @Serializedname("main")
    private Main main;
    @Serializedname("visibility")
    private Integer visibility;
    @Serializedname("wind")
    private Wind wind;
    @Serializedname("clouds")
    private Clouds clouds;
    @Serializedname("dt")
    private Integer dt;
    @Serializedname("sys")
    private Sys sys;
    @Serializedname("timezone")
    private Integer timezone;
    @Serializedname("id")
    private Integer id;
    @Serializedname("name")
    private String name;
    @Serializedname("cod")
    private Integer cod;

    public Coord getCoord() {
        return coord;
    }

    public void setCoord(Coord coord) {
        this.coord = coord;
    }

    public List<Weather> getWeather() {
        return weather;
    }

    public void setWeather(List<Weather> weather) {
        this.weather = weather;
    }

    public String getBase() {
        return base;
    }

    public void setBase(String base) {
        this.base = base;
    }

    public Main getMain() {
        return main;
    }

    public void setMain(Main main) {
        this.main = main;
    }

    public Integer getVisibility() {
        return visibility;
    }

    public void setVisibility(Integer visibility) {
        this.visibility = visibility;
    }

    public Wind getwind() {
        return wind;
    }

    public void setwind(Wind wind) {
        this.wind = wind;
    }

    public Clouds getClouds() {
        return clouds;
    }

    public void setClouds(Clouds clouds) {
        this.clouds = clouds;
    }

    public Integer getDt() {
        return dt;
    }

    public void setDt(Integer dt) {
        this.dt = dt;
    }

    public Sys getSys() {
        return sys;
    }

    public void setSys(Sys sys) {
        this.sys = sys;
    }

    public Integer getTimezone() {
        return timezone;
    }

    public void setTimezone(Integer timezone) {
        this.timezone = timezone;
    }

    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public Integer getCod() {
        return cod;
    }

    public void setCod(Integer cod) {
        this.cod = cod;
    }

    public class Clouds {

        @Serializedname("all")
        private Integer all;

        public Integer getAll() {
            return all;
        }

        public void setAll(Integer all) {
            this.all = all;
        }

    }

    public class Coord {

        @Serializedname("lon")
        private Double lon;
        @Serializedname("lat")
        private Double lat;

        public Double getLon() {
            return lon;
        }

        public void setLon(Double lon) {
            this.lon = lon;
        }

        public Double getLat() {
            return lat;
        }

        public void setLat(Double lat) {
            this.lat = lat;
        }

    }

    public class Main {

        @Serializedname("temp")
        private Double temp;
        @Serializedname("feels_like")
        private Double feelsLike;
        @Serializedname("temp_min")
        private Double tempMin;
        @Serializedname("temp_max")
        private Double tempMax;
        @Serializedname("pressure")
        private Integer pressure;
        @Serializedname("humidity")
        private Integer humidity;

        public Double getTemp() {
            return temp;
        }

        public void setTemp(Double temp) {
            this.temp = temp;
        }

        public Double getFeelsLike() {
            return feelsLike;
        }

        public void setFeelsLike(Double feelsLike) {
            this.feelsLike = feelsLike;
        }

        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 Integer getPressure() {
            return pressure;
        }

        public void setPressure(Integer pressure) {
            this.pressure = pressure;
        }

        public Integer getHumidity() {
            return humidity;
        }

        public void setHumidity(Integer humidity) {
            this.humidity = humidity;
        }

    }

    public class Sys {

        @Serializedname("type")
        private Integer type;
        @Serializedname("id")
        private Integer id;
        @Serializedname("country")
        private String country;
        @Serializedname("sunrise")
        private Integer sunrise;
        @Serializedname("sunset")
        private Integer sunset;

        public Integer getType() {
            return type;
        }

        public void setType(Integer type) {
            this.type = type;
        }

        public Integer getId() {
            return id;
        }

        public void setId(Integer id) {
            this.id = id;
        }

        public String getCountry() {
            return country;
        }

        public void setCountry(String country) {
            this.country = country;
        }

        public Integer getSunrise() {
            return sunrise;

        }

        public void setSunrise(Integer sunrise) {
            this.sunrise = sunrise;
        }

        public Integer getSunset() {
            return sunset;

        }

        public void setSunset(Integer sunset) {
            this.sunset = sunset;
        }

    }

    public class Weather {

        @Serializedname("id")
        private Integer id;
        @Serializedname("main")
        private String main;
        @Serializedname("description")
        private String description;
        @Serializedname("icon")
        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;
        }

    }

    public class Wind {

        @Serializedname("speed")
        private Double speed;
        @Serializedname("deg")
        private Integer deg;
        @Serializedname("gust")
        private Double gust;

        public Double getSpeed() {
            return speed;
        }

        public void setSpeed(Double speed) {
            this.speed = speed;
        }

        public Integer getDeg() {
            return deg;
        }

        public void setDeg(Integer deg) {
            this.deg = deg;
        }

        public Double getGust() {
            return gust;
        }

        public void setGust(Double gust) {
            this.gust = gust;
        }
    }

    public String getPrettyDate() {
        SimpleDateFormat HMM = new SimpleDateFormat("hh:mm a",Locale.US);
        final Date date = new Date(dt*1000);
        return HMM.format(date);
    }
}

我的活动类（我称之为 dt 的地方）：

public class HomeActivity extends AppCompatActivity {
    // User current time
    TextView time_field;
    ImageView Search;
    EditText textfield;
    ConstraintLayout constraintLayout;
    // For scheduling background image change
    public static int count=0;
    int[] drawable =new int[]{R.drawable.dubai,R.drawable.central_bank_of_nigeria,R.drawable.eiffel_tower,R.drawable.hong_kong,R.drawable.statue_of_liberty};
    Timer _t;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_home);

        time_field = findViewById(R.id.textView9);
        Search = findViewById(R.id.imageView4);
        textfield = findViewById(R.id.textfield);

        BottomNavigationView bottomNavigationView = findViewById(R.id.bottomNavigationView);
        final NavHostFragment navHostFragment = (NavHostFragment) getSupportFragmentManager().findFragmentById(R.id.fragment);
        assert navHostFragment != null;
        final NavController navController = navHostFragment.getNavController();
        NavigationUI.setupWithNavController(bottomNavigationView,navController);

        Search.setonClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                getWeatherData(textfield.getText().toString().trim());
                FirstFragment firstFragment = (FirstFragment) navHostFragment.getChildFragmentManager().getFragments().get(0);
                firstFragment.getWeatherData(textfield.getText().toString().trim());

                            constraintLayout = findViewById(R.id.layout);
                            constraintLayout.setBackgroundResource(R.drawable.dubai);
                            _t = new Timer();
                            _t.scheduleAtFixedrate(new TimerTask() {
                                @Override
                                public void run() {
                                    // run on ui thread
                                    runOnUiThread(() -> {
                                        if (count < drawable.length) {

                                            constraintLayout.setBackgroundResource(drawable[count]);
                                            count = (count + 1) % drawable.length;
                                        }
                                    });
                                }
                            },5000,5000);
                        }

            private void getWeatherData(String name) {

                ApiInterface apiInterface = apiclient.getClient().create(ApiInterface.class);

                Call<Example> call = apiInterface.getWeatherData(name);

                call.enqueue(new Callback<Example>() {
                    @Override
                    public void onResponse(@NotNull Call<Example> call,@NotNull Response<Example> response) {

                        assert response.body() != null;
                        time_field.setText("Last Updated:" + " " + response.body().getPrettyDate());

                    }

                    @Override
                    public void onFailure(@NotNull Call<Example> call,@NotNull Throwable t) {
                        t.printstacktrace();
                    }

                });
            }

        });
    }
}

我的 FirstFragment 类（我称之为日出和日落）：

public class FirstFragment extends Fragment {
    // User current time,current temperature,current condition,sunrise,sunset,temperature,pressure,humidity,wind_speed,visibility,clouds
    TextView current_temp,current_output,rise_time,set_time,temp_out,Press_out,Humid_out,Ws_out,Visi_out,Cloud_out;
    // Todo: Rename parameter arguments,choose names that match
// the fragment initialization parameters,e.g. ARG_ITEM_NUMBER
    private static final String ARG_ParaM1 = "param1";
    private static final String ARG_ParaM2 = "param2";

    // Todo: Rename and change types of parameters
    private String mParam1;
    private String mParam2;

    public FirstFragment() {
        // required empty public constructor
    }

    /**
     * Use this factory method to create a new instance of
     * this fragment using the provided parameters.
     *
     * @param param1 Parameter 1.
     * @param param2 Parameter 2.
     * @return A new instance of fragment SecondFragment.
     */
// Todo: Rename and change types and number of parameters
    public static FirstFragment newInstance(String param1,String param2) {
        FirstFragment fragment = new FirstFragment();
        Bundle args = new Bundle();
        args.putString(ARG_ParaM1,param1);
        args.putString(ARG_ParaM2,param2);
        fragment.setArguments(args);
        return fragment;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        if (getArguments() != null) {
            mParam1 = getArguments().getString(ARG_ParaM1);
            mParam2 = getArguments().getString(ARG_ParaM2);

        }
    }

    @Override
    public View onCreateView(LayoutInflater inflater,ViewGroup container,Bundle savedInstanceState) {
        // Inflate the layout for this fragment
        View rootView = inflater.inflate(R.layout.fragment_first,container,false);
        // For displaying weather data
        current_temp = rootView.findViewById(R.id.textView10);
        current_output = rootView.findViewById(R.id.textView11);
        rise_time = rootView.findViewById(R.id.textView25);
        set_time = rootView.findViewById(R.id.textView26);
        temp_out = rootView.findViewById(R.id.textView28);
        Press_out = rootView.findViewById(R.id.textView29);
        Humid_out = rootView.findViewById(R.id.textView30);
        Ws_out = rootView.findViewById(R.id.textView33);
        Visi_out = rootView.findViewById(R.id.textView34);
        Cloud_out = rootView.findViewById(R.id.textView35);

        return rootView;
    }

    public void getWeatherData(String name) {

        ApiInterface apiInterface = apiclient.getClient().create(ApiInterface.class);

        Call<Example> call = apiInterface.getWeatherData(name);

        call.enqueue(new Callback<Example>() {
            @Override
            public void onResponse(@NotNull Call<Example> call,@NotNull Response<Example> response) {

                assert response.body() !=null;
                current_temp.setText(response.body().getMain().getTemp() + " ℃");
                current_output.setText(response.body().getWeather().get(0).getDescription());
                rise_time.setText(response.body().getSys().getSunrise() + " ");
                set_time.setText(response.body().getSys().getSunset() + " ");
                temp_out.setText(response.body().getMain().getTemp() + " ℃");
                Press_out.setText(response.body().getMain().getPressure() + " hpa");
                Humid_out.setText(response.body().getMain().getHumidity() + " %");
                Ws_out.setText(response.body().getwind().getSpeed() + " Km/h");
                Visi_out.setText(response.body().getVisibility() + " m");
                Cloud_out.setText(response.body().getClouds().getAll()+ " %");
            }

            @Override
            public void onFailure(@NotNull Call<Example> call,@NotNull Throwable t) {
                t.printstacktrace();
            }
        });
    }
}

解决方法

tl;博士

Instant                                      // Represents a moment,a point on the timeline,as seen in UTC (an offset of zero),with resolution of nanoseconds.
.ofEpochSecond( 1_620_792_785L )             // Returns a `Instant`.
.atZone(
    ZoneId.of( "Africa/Tunis" )              // Returns a `ZoneId`.

)                                            // Returns a `ZonedDateTime`.
.format(
    DateTimeFormatter
    .ofLocalizedTime( FormatStyle.MEDIUM )   // Returns a `DateTimeFormatter`.
    .withLocale( Locale.US ) ;               // Returns another `DateTimeFormatter` rather than altering the original,per immutable objects pattern. 
)                                            // Returns a `String`.

详情

这在 Stack Overflow 上已经讲过很多次了。所以我会很简短。搜索以了解更多信息。

以毫秒的形式（即 1620792785）

不，这看起来像是整秒计数，而不是毫秒，自 1970-01-01T00:00Z 以来。

永远不要使用糟糕的遗留日期时间类。 仅使用 java.time 类。

将自 1970 年 UTC 的第一时刻以来的整秒数解析为 Instant。

Instant instant = Instant.ofEpochSecond( 1_620_792_785L ) ;

要使用特定地区人民的挂钟时间查看同一时刻，请应用时区 (ZoneId) 以获得 ZonedDateTime。

以 Continent/Region 的格式指定 real time zone name。显然，您的区域比 UTC 晚了六个小时。目前有几个时区共享与 UTC 的偏移量。我随意选择了其中之一，America/Managua。因此，请替换为您的特定时区。

ZoneId z = ZoneId.of( "America/Managua" ) ;
ZonedDateTime z = instant.atZone( z ) ;

要生成表示该值的文本，请使用 DateTimeFormatter 对象。这样的对象可以通过调用 DateTimeFormatter.ofLocalizedTime 来自动定位。

Android 26 及更高版本内置了 java.time。对于早期的 Android，大部分 java.time 功能都可以通过最新工具中的“API 脱糖”获得。

任何城市

编辑后，您更改了问题的性质，询问如何根据用户可能输入的任意城市名称更改时区。

没有神奇的解决方案。您必须将用户输入的城市转换为 particular time zone name。我知道没有图书馆可以做到这一点。从城市名称进行映射很棘手，因为城市名称远非唯一。例如，Paris France、Paris Texas。以及美国的许多斯普林菲尔德城镇。

通常应用会要求用户选择他们想要的时区。可以提示大洲缩小列表。

要获取运行时当前已知的所有时区的列表，请调用：

Set< String > timeZoneNames = ZoneId.getAvailableZoneIds() ;

查看您现在重复的问题的 excellent Answer by Ole V.V. 到 the original。