import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.core.type.TypeReference;
import com.fasterxml.jackson.databind.ObjectMapper;
import lombok.extern.slf4j.Slf4j;
import java.io.IOException;
import java.util.List;
import java.util.Map;
/**
* @author: ZhiKun Huang
* @create: 2019-02-19 10:00
**/
@Slf4j
public class JsonUtils {
public static final ObjectMapper mapper = new ObjectMapper();
public static String serialize(Object obj) {
if (obj == null) {
return null;
}
if (obj.getClass() == String.class) {
return (String) obj;
}
try {
return mapper.writeValueAsString(obj);
} catch (JsonProcessingException e) {
log.error("json序列化出错:" + obj, e);
return null;
}
}
public static <T> T parse(String json, Class<T> tClass) {
try {
return mapper.readValue(json, tClass);
} catch (IOException e) {
log.error("json解析出错:" + json, e);
return null;
}
}
public static <E> List<E> parseList(String json, Class<E> eClass) {
try {
return mapper.readValue(json, mapper.getTypeFactory().constructCollectionType(List.class, eClass));
} catch (IOException e) {
log.error("json解析出错:" + json, e);
return null;
}
}
public static <K, V> Map<K, V> parseMap(String json, Class<K> kClass, Class<V> vClass) {
try {
return mapper.readValue(json, mapper.getTypeFactory().constructMapType(Map.class, kClass, vClass));
} catch (IOException e) {
log.error("json解析出错:" + json, e);
return null;
}
}
public static <T> T nativeRead(String json, TypeReference<T> type) {
try {
return mapper.readValue(json, type);
} catch (IOException e) {
log.error("json解析出错:" + json, e);
return null;
}
}
}
如何调用呢:
@Data
@AllArgsConstructor
@NoArgsConstructor //三个注释需用lombok神器
static class User{
String name;
Integer age;
}
public static void main(String[] args) {
User user=new User("Jack",age:21);
//toString(序列化)
String json=serialize(user);
System.out.println("json="+json);
//反序列化
User user1=parse(json,User.class);
System.out.println("user1="+user1);
//toList
String json="[20,-10,5,15]";
List<Integer> list=parseList(json,Integer.class);
System.out.println("list="+list);
//toMap
String json="{\"name\":\"huang\",\"age\":\"10\"}";
Map<String, String> stringStringMap = parseMap(json, String.class, String.class);
System.out.println("map="+map);
//List中嵌套Map
String json="[{\"name\":\"huang\",\"age\":\"10\"},{\"name\":\"zhi\",\"age\":\"11\"}]";
List<Map<String, String>> maps = nativeRead(json, new TypeReference<List<Map<String, String>>>() {
});
for (Map<String, String> map : maps) {
System.out.println("map = " + map);
}
}