【日常记录】Jackson如何支持org.joda.time.DateTime

Author：赵志乾
Date：2024-06-12
Declaration：All Right Reserved！！！

问题：Jackson默认不支持时间串与org.joda.time.DateTime之间的转换；

解决方案：自定义序列化与反序列化器，并注册到ObjectMapper，代码如下：

// step1: 版本依赖
<dependency>
    <groupId>joda-time</groupId>
    <artifactId>joda-time</artifactId>
    <version>2.9.9</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.core</groupId>
    <artifactId>jackson-core</artifactId>
    <version>2.14.1</version>
</dependency>
<dependency>
    <groupId>com.fasterxml.jackson.datatype</groupId>
    <artifactId>jackson-datatype-joda</artifactId>
    <version>2.14.1</version>
</dependency>


// step2: 工具类定义
public class JacksonUtil {
    // 定义日期格式
    private static final DateTimeFormatter dateFormatter = DateTimeFormat.forPattern("yyyy-MM-dd HH:mm:ss");
    private static final ObjectMapper objectMapper = new ObjectMapper();

    // 注册自定义的序列化、反序列化器
    static {
        SimpleModule module = new SimpleModule();
        module.addSerializer(DateTime.class, new DateTimeSerializer());
        module.addDeserializer(DateTime.class, new DatetimeDeserializer());
        objectMapper.registerModule(module);
    }

    public JacksonUtil() {
    }

    
    // 对象转Json串
    public static String toJSONString(Object value) {
        try {
            return objectMapper.writeValueAsString(value);
        } catch (JsonProcessingException ex) {
            throw new RuntimeException("jacksonUtil:" + ex.getMessage(), ex);
        }
    }
    // Json串转对象
    public static <T> T parseObject(String content, Class<T> valueType) {
        try {
            return objectMapper.readValue(content, valueType);
        } catch (JsonProcessingException ex) {
            throw new RuntimeException("jacksonUtil:" + ex.getMessage(), ex);
        }
    }
    // 对象以Json串格式写入文件
    public static void writeToFile(File file, Object value) {
        try {
            objectMapper.writeValue(file, value);
        } catch (Exception ex) {
            throw new RuntimeException("jacksonUtil:" + ex.getMessage(), ex);
        }
    }
    // 从文件中读取Json串并转成对象
    public static <T> T readFromFile(File file, Class<T> valueType) {
        try {
            return objectMapper.readValue(file, valueType);
        } catch (Exception ex) {
            throw new RuntimeException("jacksonUtil:" + ex.getMessage(), ex);
        }
    }


    // 自定义反序列化器
    private static class DatetimeDeserializer extends JsonDeserializer<DateTime> {
        private DatetimeDeserializer() {
        }

        public DateTime deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
            JsonNode node = jp.getCodec().readTree(jp);
            String s = node.asText();
            return DateTime.parse(s, JacksonUtil.dateFormatter);
        }
    }
    // 自定义序列化器
    private static class DateTimeSerializer extends JsonSerializer<DateTime> {
        private DateTimeSerializer() {
        }

        public void serialize(DateTime value, JsonGenerator jgen, SerializerProvider provider) throws IOException {
            jgen.writeString(value.toString(JacksonUtil.dateFormatter));
        }
    }
}