在SpringBoot中的Jackson使用笔记

常用的java转json，json反序列化为java等方法，这里定义成一个工具类来用jackson

package cn.ath.knowwikibackend.util;import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.*;
import lombok.extern.slf4j.Slf4j;
import org.springframework.util.StringUtils;import java.io.File;
import java.io.IOException;
import java.text.SimpleDateFormat;
import java.util.List;
import java.util.Map;@Slf4j
public class JacksonUtil {private JacksonUtil() {}// 日期格式化private static final String STANDARD_FORMAT = "yyyy-MM-dd HH:mm:ss";/*** 配置正常的驼峰字段形式的json用的 OBJECT_MAPPER* {*     "name":"tom",*     "age: 22,*     "serialNumber":"STU0213131"* }*/private static final ObjectMapper OBJECT_MAPPER = new ObjectMapper();static {//对象的所有字段全部列入OBJECT_MAPPER.setSerializationInclusion(JsonInclude.Include.ALWAYS);//取消默认转换timestamps形式OBJECT_MAPPER.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);//忽略空Bean转json的错误OBJECT_MAPPER.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);//所有的日期格式都统一为以下的样式，即yyyy-MM-dd HH:mm:ssOBJECT_MAPPER.setDateFormat(new SimpleDateFormat(STANDARD_FORMAT));//忽略 在json字符串中存在，但是在java对象中不存在对应属性的情况。防止错误OBJECT_MAPPER.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);}/*** 配置 下划线字段形式的json用的 OBJECT_MAPPER* {*     "name":"tom",*     "age: 22,*     "serial_number":"STU0213131"* }*/private static final ObjectMapper OBJECT_MAPPER_SNAKE_CASE = new ObjectMapper();static {//对象的所有字段全部列入OBJECT_MAPPER_SNAKE_CASE.setSerializationInclusion(JsonInclude.Include.ALWAYS);//取消默认转换timestamps形式OBJECT_MAPPER_SNAKE_CASE.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false);//忽略空Bean转json的错误OBJECT_MAPPER_SNAKE_CASE.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false);//所有的日期格式都统一为以下的样式，即yyyy-MM-dd HH:mm:ssOBJECT_MAPPER_SNAKE_CASE.setDateFormat(new SimpleDateFormat(STANDARD_FORMAT));//忽略 在json字符串中存在，但是在java对象中不存在对应属性的情况。防止错误OBJECT_MAPPER_SNAKE_CASE.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false);//转换为下划线OBJECT_MAPPER_SNAKE_CASE.setPropertyNamingStrategy(PropertyNamingStrategy.SNAKE_CASE);}/*** 配置属性名不带引号的 非标准格式 的json 用的 OBJECT_MAPPER** Neo4j场景会用到这种格式* {*     name:"tom",*     age: 22,*     serialNumber:"STU0213131"* }** 如这个cql语句*  merge(:学生 {name:"tom",age: 22,serialNumber:"STU0213131"})*/private static final ObjectMapper OBJECT_MAPPER_BY_QUOTE_FIELD_NAMES = new ObjectMapper();static {OBJECT_MAPPER_BY_QUOTE_FIELD_NAMES.configure(JsonGenerator.Feature.QUOTE_FIELD_NAMES, false);}/*** map转换成json格式String* @param map Map<String,Object>* @return String*/public static String map2String(Map<String,Object> map){String propertiesString = "";try {propertiesString = OBJECT_MAPPER_BY_QUOTE_FIELD_NAMES.writeValueAsString(map);} catch (JsonProcessingException e) {log.error(e.getMessage());}return propertiesString;}/*** 对象转Json格式字符串** @param obj 对象* @return Json格式字符串*/public static <T> String obj2String(T obj) {if (obj == null) {return null;}try {return obj instanceof String ? (String) obj : OBJECT_MAPPER.writeValueAsString(obj);} catch (JsonProcessingException e) {log.warn("Parse Object to String error : {}", e.getMessage());return null;}}/*** 对象转file* @param fileName String* @param obj  Object*/public static void obj2File(String fileName,Object obj){if (obj == null){return;}try {OBJECT_MAPPER.writeValue(new File(fileName),obj);} catch (IOException e) {e.printStackTrace();}}/*** 对象转Json格式字符串(格式化的Json字符串)** @param obj 对象* @return 美化的Json格式字符串*/public static <T> String obj2StringPretty(T obj) {if (obj == null) {return null;}try {return obj instanceof String ? (String) obj : OBJECT_MAPPER.writerWithDefaultPrettyPrinter().writeValueAsString(obj);} catch (JsonProcessingException e) {log.warn("Parse Object to String error : {}", e.getMessage());return null;}}/*** 字符串转换为自定义对象** @param str   要转换的字符串* @param clazz 自定义对象的class对象* @return 自定义对象*/public static <T> T string2Obj(String str, Class<T> clazz) {if (StringUtils.isEmpty(str) || clazz == null) {return null;}try {return clazz.equals(String.class) ? (T) str : OBJECT_MAPPER.readValue(str, clazz);} catch (Exception e) {log.warn("Parse String to Object error : {}", e.getMessage());return null;}}/*** 对象转Json格式字符串; 属性名从驼峰改为下划线形式** @param obj 对象* @return Json格式字符串*/public static <T> String obj2StringFieldSnakeCase(T obj) {if (obj == null) {return null;}try {ObjectMapper objectMapper = OBJECT_MAPPER_SNAKE_CASE;return obj instanceof String ? (String) obj : objectMapper.writeValueAsString(obj);} catch (JsonProcessingException e) {log.warn("Parse Object to String error : {}", e.getMessage());return null;}}/*** 字符串转换为自定义对象； 属性名从下划线形式改为驼峰** @param str   要转换的字符串* @param clazz 自定义对象的class对象* @return 自定义对象*/public static <T> T string2ObjFieldLowerCamelCase(String str, Class<T> clazz) {if (StringUtils.isEmpty(str) || clazz == null) {return null;}try {ObjectMapper objectMapper = OBJECT_MAPPER_SNAKE_CASE;return clazz.equals(String.class) ? (T) str : objectMapper.readValue(str, clazz);} catch (Exception e) {log.warn("Parse String to Object error : {}", e.getMessage());return null;}}/*** 字符串转换为自定义对象(List)； 属性名从下划线形式改为驼峰** @param str           要转换的字符串* @param typeReference 自定义对象的typeReference List 对象* @return 自定义对象*/public static <T> List<T> string2ListFieldLowerCamelCase(String str, TypeReference<List<T>> typeReference) {if (StringUtils.isEmpty(str) || typeReference == null) {return null;}try {ObjectMapper objectMapper = OBJECT_MAPPER_SNAKE_CASE;return objectMapper.readValue(str, typeReference);} catch (Exception e) {log.warn("Parse String to Object error : {}", e.getMessage());return null;}}/*** 字符串转换为自定义字段转为list* @param str  String* @param typeReference   TypeReference* @param <T>  泛型* @return T   类型*/public static <T> T string2Obj(String str, TypeReference<T> typeReference) {if (StringUtils.isEmpty(str) || typeReference == null) {return null;}try {return (T) (typeReference.getType().equals(String.class) ? str : OBJECT_MAPPER.readValue(str, typeReference));} catch (IOException e) {log.warn("Parse String to Object error", e);return null;}}public static <T> T string2Obj(String str, Class<?> collectionClazz, Class<?>... elementClazzes) {JavaType javaType = OBJECT_MAPPER.getTypeFactory().constructParametricType(collectionClazz, elementClazzes);try {return OBJECT_MAPPER.readValue(str, javaType);} catch (IOException e) {log.warn("Parse String to Object error : {}" + e.getMessage());return null;}}
}

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在springboot项目中配置全局序列化date返回前端字符串

需要在yml里配置jsckson

spring:jackson:time-zone: GMT+8date-format: yyyy-MM-dd HH:mm:ss