JavaFX天气应用切换首个城市触发400错误求助

报错信息 #

Exception in thread "JavaFX Application Thread" java.lang.RuntimeException: java.lang.reflect.InvocationTargetException
    at javafx.fxml/javafx.fxml.FXMLLoader$MethodHandler.invoke(FXMLLoader.java:1787)
    at javafx.fxml/javafx.fxml.FXMLLoader$ControllerMethodEventHandler.handle(FXMLLoader.java:1670)
    ...
Caused by: net.aksingh.owmjapis.api.APIException: API call gave error: 400 - Bad Request
    at owm.japis@2.5.3.0/net.aksingh.owmjapis.core.OWM.hourlyWeatherForecastByCityName(OWM.kt:331)
    at WeatherApp/com.dariuszkrygier.model.WeatherForecastFetcher.getWeatherForecast(WeatherForecastFetcher.java:16)
    at WeatherApp/com.dariuszkrygier.controller.MainWindowController.showCurrentWeather(MainWindowController.java:285)
    at WeatherApp/com.dariuszkrygier.controller.MainWindowController.changeFirstCityLocationButtonAction(MainWindowController.java:202)
    ... 58 more

问题代码片段 #

WeatherForecastFetcher.java #

public Weather getWeatherForecast(String cityNameWithCountryCode) throws APIException {
    // 问题行：传入的参数格式无效，触发API 400错误
    HourlyWeatherForecast hourlyWeatherForecast = owm.hourlyWeatherForecastByCityName(cityNameWithCountryCode);
    if (hourlyWeatherForecast.hasRespCode() && hourlyWeatherForecast.getRespCode().equals("200")) {
        return new Weather(hourlyWeatherForecast);
    }
    return null;
}

MainWindowController.java #

private void showCurrentWeather(TextField locationField, Label locationName, Label locationDate,
                                ImageView locationImage, Label locationTemp, Label locationWeather
                                ) throws APIException {
    // 问题行：直接传入输入框原始文本，未做清洗校验
    var weather = weatherForecastFetcher.getWeatherForecast(locationField.getText());
    // ... 后续UI渲染逻辑
}

@FXML
void changeFirstCityLocationButtonAction() throws APIException {
    if (firstFieldIsValid()) {
        // 问题行：未捕获API异常，导致JavaFX线程崩溃
        showCurrentWeather(firstCityPicker, firstCity, firstCityFirstDayDate, firstCityFirstDayImage,
                firstCityFirstDayTemp, firstCityFirstDayDescription );
        // ... 其他showNextDays调用
    }
}

排查分析 #

1. API 400错误本质：OWM API返回400表示请求参数不符合要求，对比第二个城市正常的情况，说明第一个城市的输入存在格式问题（如含多余空格、空字符串、未遵循"城市名,国家代码"的格式规范）。
2. 输入校验逻辑薄弱：firstFieldIsValid()的校验规则可能未过滤无效输入，同时获取输入框文本时未做清洗处理。
3. 异常处理缺失：直接抛出APIException未捕获，导致JavaFX应用线程崩溃。

解决方案 #

1. 清洗输入参数并添加格式校验 #

修改getWeatherForecast方法，对输入做清洗和格式校验：

public Weather getWeatherForecast(String cityNameWithCountryCode) throws APIException, IllegalArgumentException {
    // 去除前后空格，避免无效空白字符
    String cleanedInput = cityNameWithCountryCode.trim();
    // 校验输入非空且符合"城市名,国家代码"格式
    if (cleanedInput.isEmpty() || !cleanedInput.contains(",")) {
        throw new IllegalArgumentException("请输入正确格式：城市名,国家代码（例如：London,UK）");
    }
    HourlyWeatherForecast hourlyWeatherForecast = owm.hourlyWeatherForecastByCityName(cleanedInput);
    if (hourlyWeatherForecast.hasRespCode() && hourlyWeatherForecast.getRespCode().equals("200")) {
        return new Weather(hourlyWeatherForecast);
    }
    return null;
}

2. 完善输入框文本获取逻辑 #

修改showCurrentWeather中获取输入的代码，确保传入清洗后的文本：

var weather = weatherForecastFetcher.getWeatherForecast(locationField.getText().trim());

3. 强化输入校验规则 #

更新firstFieldIsValid()，确保过滤无效输入：

private boolean firstFieldIsValid() {
    String input = firstCityPicker.getText().trim();
    // 校验非空且包含逗号分隔符
    return !input.isEmpty() && input.contains(",");
}

4. 添加异常捕获避免程序崩溃 #

修改changeFirstCityLocationButtonAction方法，捕获异常并给用户友好提示：

@FXML
void changeFirstCityLocationButtonAction() {
    if (firstFieldIsValid()) {
        try {
            showCurrentWeather(firstCityPicker, firstCity, firstCityFirstDayDate, firstCityFirstDayImage,
                    firstCityFirstDayTemp, firstCityFirstDayDescription );
            // day2
            showNextDays(firstCityPicker, 8, firstCitySecondDayDate, firstCitySecondDayImage,
                    firstCitySecondDayTemp, firstCitySecondDayDescription);
            // day3
            showNextDays(firstCityPicker, 16, firstCityThirdDayDate, firstCityThirdDayImage,
                    firstCityThirdDayTemp, firstCityThirdDayDescription);
            // day4
            showNextDays(firstCityPicker, 24, firstCityFourthDayDate, firstCityFourthDayImage,
                    firstCityFourthDayTemp, firstCityFourthDayDescription);
            // day5
            showNextDays(firstCityPicker, 32, firstCityFifthDayDate, firstCityFifthDayImage,
                    firstCityFifthDayTemp, firstCityFifthDayDescription);
        } catch (APIException e) {
            Alert alert = new Alert(Alert.AlertType.ERROR);
            alert.setTitle("获取天气失败");
            alert.setHeaderText("API请求错误");
            alert.setContentText("无法获取天气数据，请检查城市名称是否正确");
            alert.showAndWait();
        } catch (IllegalArgumentException e) {
            Alert alert = new Alert(Alert.AlertType.WARNING);
            alert.setTitle("输入格式错误");
            alert.setHeaderText("请检查输入内容");
            alert.setContentText(e.getMessage());
            alert.showAndWait();
        } catch (Exception e) {
            Alert alert = new Alert(Alert.AlertType.ERROR);
            alert.setTitle("程序错误");
            alert.setHeaderText("未知错误");
            alert.setContentText("操作失败，请重试");
            alert.showAndWait();
        }
    }
}

内容的提问来源于stack exchange，提问作者dar1o