FastJson、Jackson解决Json转换对象、简单对象问题
在开发过程中最常见的就是Json格局转化问题。包含Json转对象，转数据，转Map等等。常见解决json的类库FastJson，Jackson为此我针对他们做了一些总结，如有欠缺能够留言。心愿能够帮忙大家。
FastJson
筹备两个套娃的类
@Data@AllArgsConstructor@NoArgsConstructorpublic class FastJsonPerson { private String name; private Integer agexx; private String other; private List<Card> cards;}@Data@NoArgsConstructor@AllArgsConstructorpublic class Card { private String cardName; private Date cardTime;}1.对象转字符串
@Test public void transformString(){ FastJsonPerson person; person = new FastJsonPerson(); person.setName("兵长"); person.setAgexx(18); person.setOther("其余要被屏蔽"); person.setCards(Arrays.asList(new Card("招商",new Date()), new Card("浦发",new Date()))); String personString = JSON.toJSONString(person); System.out.println(personString); }// 后果：{"agexx":18,"cards":[{"cardName":"招商","cardTime":1631188795258},{"cardName":"浦发","cardTime":1631188795258}],"name":"兵长","other":"其余要被屏蔽"}在转化的过程不想要某个字段能够加上@JSONField(serialize = false)，留神不是@jsonIgnore,那个是jackson的。
在转化的过程中还想更换字段别名@JSONField(name="xxx")
格式化日期@JSONField(format="yyyy-MM-dd HH:mm:ss")
接下来扭转对应的实体类实现上述三个要求。
@Data@AllArgsConstructor@NoArgsConstructorpublic class FastJsonPerson { private String name; @JSONField(name="age") private Integer agexx; @JSONField(serialize = false) private String other; private List<Card> cards;}@Data@NoArgsConstructor@AllArgsConstructorpublic class Card { private String cardName; @JSONField(format="yyyy-MM-dd HH:mm:ss") private Date cardTime;}再次执行上边的测试方法，你会发现后果变成;agexx--->age ，工夫格局变成了失常的，other字段被疏忽。
{"age":18,"cards":[{"cardName":"招商","cardTime":"2021-09-09 20:12:26"},{"cardName":"浦发","cardTime":"2021-09-09 20:12:26"}],"name":"兵长"}2.字符串转对象,汇合对象；
@Test public void stringToObject() { //针对于简略的字符串，咱们能够通过转成Array，而后通过名字获取内容。 String s = "{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"}"; JSONObject object = JSON.parseObject(s); System.out.println(object.get("age")); System.out.println(object.get("name")); System.out.println(object.get("cards")); String list = "[{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"},{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"}]"; List<FastJsonPerson> personList = JSON.parseArray(list, FastJsonPerson.class); System.out.println(personList); }3.字符串转Map
@Test public void stringToMap(){ String s = "{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"}"; Map map = (Map<String,Object>)JSON.parseObject(s); System.out.println(map); }Jackson
筹备两个套娃类
@Data@NoArgsConstructor@AllArgsConstructorpublic class JacksonCard { private String cardName; private Date cardTime;}@Data@NoArgsConstructor@AllArgsConstructorpublic class JacksonPerson { private String name; private Integer agexx; private String other; private List<JacksonCard> cards;}1.对象转字符串
@SneakyThrows@Testpublic void transformToString (){ JacksonPerson person = new JacksonPerson(); person.setName("兵长"); person.setAgexx(18); person.setOther("其余要被屏蔽"); person.setCards(Arrays.asList(new JacksonCard("招商",new Date()), new JacksonCard("浦发",new Date()))); ObjectMapper objectMapper = new ObjectMapper(); System.out.println(objectMapper.writeValueAsString(person));}// 后果：{"name":"兵长","agexx":18,"other":"其余要被屏蔽","cards":[{"cardName":"招商","cardTime":1631242139184},{"cardName":"浦发","cardTime":1631242139184}]}在转化的过程不想要某个字段能够加上@JsonIgnore
在转化的过程中还想更换字段别名@JsonProperty("age")
格式化日期@JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8")
根据上述形容革新对应的实体类
@Data@NoArgsConstructor@AllArgsConstructorpublic class JacksonPerson { private String name; @JsonProperty("age") private Integer agexx; @JsonIgnore private String other; private List<JacksonCard> cards;}@Data@NoArgsConstructor@AllArgsConstructorpublic class JacksonCard { private String cardName; @JsonFormat(pattern = "yyyy-MM-dd HH:mm:ss", timezone = "GMT+8") private Date cardTime;}2.字符串转对象,对象汇合,简单对象
@Testpublic void transformToObject() throws IOException { String s = "{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"}"; String list = "[{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"},{\"age\":18,\"cards\":[{\"cardName\":\"招商\",\"cardTime\":\"2021-09-09 20:12:26\"},{\"cardName\":\"浦发\",\"cardTime\":\"2021-09-09 20:12:26\"}],\"name\":\"兵长\"}]"; ObjectMapper objectMapper = new ObjectMapper(); System.out.println(objectMapper.readValue(s, JacksonPerson.class)); List<JacksonPerson> personList = (List<JacksonPerson>)objectMapper.readValue(list, objectMapper.getTypeFactory().constructParametricType(List.class, JacksonPerson.class)); System.out.println(personList); // 如果多层套娃，你能够使TypeReference，万能想要的都有 List<Map<String,Object>> personList1 = objectMapper.readValue(list, new TypeReference<List<Map<String,Object>>>(){}); System.out.println(personList1);}下边是JsonUtils工具类。
package com.cn.zj.json;import com.fasterxml.jackson.annotation.JsonInclude;import com.fasterxml.jackson.core.type.TypeReference;import com.fasterxml.jackson.databind.DeserializationFeature;import com.fasterxml.jackson.databind.ObjectMapper;import com.fasterxml.jackson.databind.SerializationFeature;import lombok.extern.slf4j.Slf4j;import org.springframework.util.StringUtils;import java.text.SimpleDateFormat;/** * @description: * @author: wangdakai * @date: 2021/9/10 */@Slf4jpublic class JsonUtils { private static ObjectMapper objectMapper = new ObjectMapper(); static { //序列化的时候序列对象的所有属性 objectMapper.setSerializationInclusion(JsonInclude.Include.ALWAYS); //反序列化的时候如果多了其余属性,不抛出异样 objectMapper.configure(DeserializationFeature.FAIL_ON_UNKNOWN_PROPERTIES, false); //如果是空对象的时候,不抛异样 objectMapper.configure(SerializationFeature.FAIL_ON_EMPTY_BEANS, false); //勾销工夫的转化格局,默认是工夫戳,能够勾销,同时须要设置要体现的工夫格局 objectMapper.configure(SerializationFeature.WRITE_DATES_AS_TIMESTAMPS, false); objectMapper.setDateFormat(new SimpleDateFormat("yyyy-MM-dd HH:mm:ss")); } /** * 对象转Json * @param obj * @param <T> * @return */ public static <T>String objectToJson(T obj){ if(obj == null){ return null; } try { return obj instanceof String ? (String) obj : objectMapper.writeValueAsString(obj); } catch (Exception e) { log.warn("Parse Object to Json error",e); e.printStackTrace(); return null; } } /** * json转对象 * @param src * @param clazz * @param <T> * @return */ public static <T>T jsonToObject(String src,Class<T> clazz){ if(StringUtils.isEmpty(src) || clazz == null){ return null; } try { return clazz.equals(String.class) ? (T) src : objectMapper.readValue(src,clazz); } catch (Exception e) { log.warn("Parse Json to Object error",e); e.printStackTrace(); return null; } } /** * json转想要的对象；应答各种简单格局的对象很万能。 * @param src * @param typeReference * @param <T> * @return */ public static <T>T jsonToObject(String src, TypeReference<T> typeReference){ if(StringUtils.isEmpty(src) || typeReference == null){ return null; } try { return (T)(typeReference.getType().equals(String.class) ? src : objectMapper.readValue(src, typeReference)); } catch (Exception e) { log.warn("Parse Json to Object error",e); e.printStackTrace(); return null; } } /** * json转成对象 * @param str * @param collectionClass * @param elementClasses * @param <T> * @return */ public static <T> T jsonToTransfer(String str, Class<?> collectionClass, Class<?>... elementClasses) { try { return (T)objectMapper.readValue(str, objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses)); } catch (Exception e) { log.warn("Parse Json to Object error",e); e.printStackTrace(); } return null; }}另外也能够用其他人写好的工具包，https://hutool.cn/docs/#/json...理性去的能够去看看。如果只是解决json就没必要，里边的货色太多。人生一世难得糊涂。