ObjectMapper常规设置和使用

public class JsonUtils {

    private static ObjectMapper objectMapper;

public static ObjectMapper getObjectMapper(){
   if (objectMapper == null) {
        ObjectMapper objectMapper = new ObjectMapper();
        objectMapper.configure(MapperFeature.AUTO_DETECT_CREATORS, false);
        objectMapper.configure(MapperFeature.AUTO_DETECT_FIELDS, false);
        objectMapper.configure(MapperFeature.AUTO_DETECT_GETTERS, true);
        objectMapper.configure(MapperFeature.AUTO_DETECT_SETTERS, true);
        objectMapper.configure(MapperFeature.AUTO_DETECT_IS_GETTERS, true);
        objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);
        //20200422 空string2null
        objectMapper.configure(DeserializationFeature.ACCEPT_EMPTY_STRING_AS_NULL_OBJECT,true);
        objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);
//        objectMapper.configure(SerializationFeature.WRITE_EMPTY_JSON_ARRAYS, false);
        objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, true);
        objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);
        objectMapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
//            objectMapper.configure(DeserializationFeature.USE_JAVA_ARRAY_FOR_JSON_ARRAY, true);

// objectMapper.setPropertyNamingStrategy(PropertyNamingStrategy.CAMEL_CASE_TO_LOWER_CASE_WITH_UNDERSCORES);
    }
        return objectMapper;


    }

public static Map string2Map(String str){
    try {
        return objectMapper.readValue(str, Map.class);
    } catch (IOException e) {
        return null;
    }
}

    public static <T> String bean2Json(T bean) {
        try {
            return getObjectMapper().writeValueAsString(bean);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public static String map2Json(Map map) {
        try {
            return getObjectMapper().writeValueAsString(map);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public static String list2Json(List list) {
        try {
            return getObjectMapper().writeValueAsString(list);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return "";
    }

    public static <T> T json2Bean(String json, Class<T> beanClass) {
        try {
            return getObjectMapper().readValue(json, beanClass);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static <T> List<T> json2List(String json, Class<T> beanClass) {
        try {

            return (List<T>) getObjectMapper().readValue(json, getCollectionType(List.class, beanClass));
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static Map json2Map(String json) {
        try {

            return (Map) getObjectMapper().readValue(json, Map.class);
        } catch (Exception e) {
            e.printStackTrace();
        }
        return null;
    }

    public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) {
        return getObjectMapper().getTypeFactory().constructParametricType(collectionClass, elementClasses);
    }
}