问题描述

fastjson通过代码指定全局序列化返回时间格式，导致使用JSONField注解标注属性的特殊日期返回格式失效

使用版本

全局设置代码

public class WebConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        //1.需要定义一个convert转换消息的对象;
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //2.添加fastJson的配置信息，比如：是否要格式化返回的json数据;
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        //全局指定了日期格式
        fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss");
        //3处理中文乱码问题
        List<MediaType> fastMediaTypes = new ArrayList<>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        //4.在convert中添加配置信息.
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        //5.将convert添加到converters当中.
        converters.add(fastJsonHttpMessageConverter);
    }
}

属性设置代码

    @JSONField(format = "yyyy-MM-dd")
    private Date addDate;

返回结果

请求接口后addDate字段返回的格式为2022-12-17 13:26:45，仍然为全局日期格式，并不设置JSONField后期望的2022-12-17格式

解决方案

统一扫描

系统启动时扫描对应基类的子类，通过反射获取标注了JSONField注解的字段并获取对应的format值

public class FastJsonUtil {
    private static HashMap<String, String> dateMap = new HashMap();
    public static void scanDate2Json(Class runtimeClass, List<String> extraPackageNameList) {
        List<Class> filterClassList = new ArrayList<>();
        filterClassList.add(BaseSystemObject.class);
        List<Class<?>> scanClassList = new ArrayList<>();
        if (!runtimeClass.getPackage().getName().equals(Application.class.getPackage().getName())) {
            scanClassList.addAll(ScanUtil.getAllClassByPackageName(runtimeClass.getPackage(), filterClassList));
        }
        for (String packageName : extraPackageNameList) {
            scanClassList.addAll(ScanUtil.getAllClassByPackageName(packageName, filterClassList));
        }
        for (Class clazz : scanClassList) {
            List<Field> fs = Arrays.asList(clazz.getDeclaredFields());
            for (Field field : fs) {
                field.setAccessible(true);
                if (field.getType() == Date.class) {
                    JSONField jsonField = field.getAnnotation(JSONField.class);
                    if (jsonField != null && !StringUtil.isEmpty(jsonField.format())) {
                        dateMap.put(clazz.getName() + "|" + field.getName(), jsonField.format());
                    }
                }
            }
        }
    }
    public static boolean checkDate2Json(String key){
        return dateMap.containsKey(key);
    }
    public static String getDate2JsonFormat(String key){
        return dateMap.get(key);
    }
}

统一修改

实现fastjson的扩展过滤器ValueFilter进行序列化后的值修改，并注册到配置中去

public class FastJsonPropertyValueFilter implements ValueFilter {
    @Override
    public Object process(Object source, String name, Object value) {
        String key = source.getClass().getName() + "|" + name;
        if (value != null && FastJsonUtil.checkDate2Json(key)) {
            String format = FastJsonUtil.getDate2JsonFormat(key);
            DateFormat df = new SimpleDateFormat(format);
            return df.format(value);
        }
        return value;
    }
}

public class WebConfig implements WebMvcConfigurer {
    @Override
    public void configureMessageConverters(List<HttpMessageConverter<?>> converters) {
        //1.需要定义一个convert转换消息的对象;
        FastJsonHttpMessageConverter fastJsonHttpMessageConverter = new FastJsonHttpMessageConverter();
        //2.添加fastJson的配置信息，比如：是否要格式化返回的json数据;
        FastJsonConfig fastJsonConfig = new FastJsonConfig();
        //全局指定了日期格式
        fastJsonConfig.setDateFormat("yyyy-MM-dd HH:mm:ss");
        //指定json返回规则
        fastJsonConfig.setSerializeFilters(new FastJsonPropertyValueFilter());
        //3处理中文乱码问题
        List<MediaType> fastMediaTypes = new ArrayList<>();
        fastMediaTypes.add(MediaType.APPLICATION_JSON_UTF8);
        //4.在convert中添加配置信息.
        fastJsonHttpMessageConverter.setSupportedMediaTypes(fastMediaTypes);
        fastJsonHttpMessageConverter.setFastJsonConfig(fastJsonConfig);
        //5.将convert添加到converters当中.
        converters.add(fastJsonHttpMessageConverter);
    }
}