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
@NoArgsConstructor
public class FastJsonPerson {
private String name;
private Integer agexx;
private String other;
private List<Card> cards;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public 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
@NoArgsConstructor
public class FastJsonPerson {
private String name;
@JSONField(name="age")
private Integer agexx;
@JSONField(serialize = false)
private String other;
private List<Card> cards;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public 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
@AllArgsConstructor
public class JacksonCard {
private String cardName;
private Date cardTime;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public class JacksonPerson {
private String name;
private Integer agexx;
private String other;
private List<JacksonCard> cards;
}
1. 对象转字符串
@SneakyThrows
@Test
public 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
@AllArgsConstructor
public class JacksonPerson {
private String name;
@JsonProperty("age")
private Integer agexx;
@JsonIgnore
private String other;
private List<JacksonCard> cards;
}
@Data
@NoArgsConstructor
@AllArgsConstructor
public 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
@Test
public 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
*/
@Slf4j
public 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。