package com.taotao.utils;import java.util.List;import com.fasterxml.jackson.core.JsonProcessingException;import com.fasterxml.jackson.databind.JavaType;import com.fasterxml.jackson.databind.ObjectMapper;public class JsonUtils {    // 定义jackson对象    private static final ObjectMapper MAPPER = new ObjectMapper();    /**     * 将对象转换成json字符串     */    public static String objectToJson(Object data) {        try {            String string = MAPPER.writeValueAsString(data);            return string;        } catch (JsonProcessingException e) {            e.printStackTrace();        }        return null;    }        /**     * 将json结果集转化为对象     *      */    public static <T> T jsonToPojo(String jsonData, Class<T> beanType) {        try {            T t = MAPPER.readValue(jsonData, beanType);            return t;        } catch (Exception e) {            e.printStackTrace();        }        return null;    }        /**     * 将json数据转换成pojo对象list     */    public static <T>List<T> jsonToList(String jsonData, Class<?> target, Class<T> beanType) {                JavaType javaType = MAPPER.getTypeFactory().constructParametricType(target, beanType);                try {            List<T> list = MAPPER.readValue(jsonData, javaType);            return list;        } catch (Exception e) {            e.printStackTrace();        }                return null;    }        public static void main(String[] args) {        System.out.println(JsonUtils.jsonToPojo("[{\"username\":\"youth\"}]", List.class).get(0).getClass());    }    }