content: package com.yuu.ymall.commons.utils;
  
  import com.fasterxml.jackson.annotation.JsonInclude;
  import com.fasterxml.jackson.core.type.TypeReference;
  import com.fasterxml.jackson.databind.DeserializationFeature;
  import com.fasterxml.jackson.databind.JavaType;
  import com.fasterxml.jackson.databind.JsonNode;
  import com.fasterxml.jackson.databind.ObjectMapper;
  
  import java.util.ArrayList;
  import java.util.HashMap;
  import java.util.List;
  import java.util.Map;
  
  /**
   * JSON 转换工具类
   *
   * @Classname MapperUtil
   * @Date 2019/5/13 19:46
   * @Created by Yuu
   */
  public class MapperUtil {
      private final static ObjectMapper objectMapper = new ObjectMapper();
  
      public static ObjectMapper getInstance() {
          return objectMapper;
      }
  
      /**
       * 转换为 JSON 字符串
       *
       * @param obj
       * @return
       * @throws Exception
       */
      public static String obj2json(Object obj) throws Exception {
          return objectMapper.writeValueAsString(obj);
      }
  
      /**
       * 转换为 JSON 字符串，忽略空值
       *
       * @param obj
       * @return
       * @throws Exception
       */
      public static String obj2jsonIgnoreNull(Object obj) throws Exception {
          ObjectMapper mapper = new ObjectMapper();
          mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
          return mapper.writeValueAsString(obj);
      }
  
      /**
       * 转换为 JavaBean
       *
       * @param jsonString
       * @param clazz
       * @return
       * @throws Exception
       */
      public static <T> T json2pojo(String jsonString, Class<T> clazz) throws Exception {
          objectMapper.configure(DeserializationFeature.ACCEPT_SINGLE_VALUE_AS_ARRAY, true);
          return objectMapper.readValue(jsonString, clazz);
      }
  
      /**
       * 将指定节点的 JSON 数据转换为 JavaBean
       *
       * @param jsonString
       * @param clazz
       * @return
       * @throws Exception
       */
      public static <T> T json2pojoByTree(String jsonString, String treeNode, Class<T> clazz) throws Exception {
          JsonNode jsonNode = objectMapper.readTree(jsonString);
          JsonNode data = jsonNode.findPath(treeNode);
          return json2pojo(data.toString(), clazz);
      }
  
      /**
       * 字符串转换为 Map<String, Object>
       *
       * @param jsonString
       * @return
       * @throws Exception
       */
      public static <T> Map<String, Object> json2map(String jsonString) throws Exception {
          ObjectMapper mapper = new ObjectMapper();
          mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);
          return mapper.readValue(jsonString, Map.class);
      }
  
      /**
       * 字符串转换为 Map<String, T>
       */
      public static <T> Map<String, T> json2map(String jsonString, Class<T> clazz) throws Exception {
          Map<String, Map<String, Object>> map = objectMapper.readValue(jsonString, new TypeReference<Map<String, T>>() {
          });
          Map<String, T> result = new HashMap<String, T>();
          for (Map.Entry<String, Map<String, Object>> entry : map.entrySet()) {
              result.put(entry.getKey(), map2pojo(entry.getValue(), clazz));
          }
          return result;
      }
  
      /**
       * 深度转换 JSON 成 Map
       *
       * @param json
       * @return
       */
      public static Map<String, Object> json2mapDeeply(String json) throws Exception {
          return json2MapRecursion(json, objectMapper);
      }
  
      /**
       * 把 JSON 解析成 List，如果 List 内部的元素存在 jsonString，继续解析
       *
       * @param json
       * @param mapper 解析工具
       * @return
       * @throws Exception
       */
      private static List<Object> json2ListRecursion(String json, ObjectMapper mapper) throws Exception {
          if (json == null) {
              return null;
          }
  
          List<Object> list = mapper.readValue(json, List.class);
  
          for (Object obj : list) {
              if (obj != null && obj instanceof String) {
                  String str = (String) obj;
                  if (str.startsWith("[")) {
                      obj = json2ListRecursion(str, mapper);
                  } else if (obj.toString().startsWith("{")) {
                      obj = json2MapRecursion(str, mapper);
                  }
              }
          }
  
          return list;
      }
  
      /**
       * 把 JSON 解析成 Map，如果 Map 内部的 Value 存在 jsonString，继续解析
       *
       * @param json
       * @param mapper
       * @return
       * @throws Exception
       */
      private static Map<String, Object> json2MapRecursion(String json, ObjectMapper mapper) throws Exception {
          if (json == null) {
              return null;
          }
  
          Map<String, Object> map = mapper.readValue(json, Map.class);
  
          for (Map.Entry<String, Object> entry : map.entrySet()) {
              Object obj = entry.getValue();
              if (obj != null && obj instanceof String) {
                  String str = ((String) obj);
  
                  if (str.startsWith("[")) {
                      List<?> list = json2ListRecursion(str, mapper);
                      map.put(entry.getKey(), list);
                  } else if (str.startsWith("{")) {
                      Map<String, Object> mapRecursion = json2MapRecursion(str, mapper);
                      map.put(entry.getKey(), mapRecursion);
                  }
              }
          }
  
          return map;
      }
  
      /**
       * 将 JSON 数组转换为集合
       *
       * @param jsonArrayStr
       * @param clazz
       * @return
       * @throws Exception
       */
      public static <T> List<T> json2list(String jsonArrayStr, Class<T> clazz) throws Exception {
          JavaType javaType = getCollectionType(ArrayList.class, clazz);
          List<T> list = (List<T>) objectMapper.readValue(jsonArrayStr, javaType);
          return list;
      }
  
      /**
       * 将指定节点的 JSON 数组转换为集合
       * @param jsonStr JSON 字符串
       * @param treeNode 查找 JSON 中的节点
       * @return
       * @throws Exception
       */
      public static <T> List<T> json2listByTree(String jsonStr, String treeNode, Class<T> clazz) throws  Exception {
          JsonNode jsonNode = objectMapper.readTree(jsonStr);
          JsonNode data = jsonNode.findPath(treeNode);
          return json2list(data.toString(), clazz);
      }
  
      /**
       * 获取泛型的 Collection Type
       *
       * @param collectionClass 泛型的Collection
       * @param elementClasses  元素类
       * @return JavaType Java类型
       * @since 1.0
       */
      public static JavaType getCollectionType(Class<?> collectionClass, Class<?>... elementClasses) {
          return objectMapper.getTypeFactory().constructParametricType(collectionClass, elementClasses);
      }
  
      /**
       * 将 Map 转换为 JavaBean
       *
       * @param map
       * @param clazz
       * @return
       */
      public static <T> T map2pojo(Map map, Class<T> clazz) {
          return objectMapper.convertValue(map, clazz);
      }
  
      /**
       * 将 Map 转换为 JSON
       *
       * @param map
       * @return
       */
      public static String mapToJson(Map map) {
          try {
              return objectMapper.writeValueAsString(map);
          } catch (Exception e) {
              e.printStackTrace();
          }
          return "";
      }
  
      /**
       * 将 JSON 对象转换为 JavaBean
       *
       * @param obj
       * @param clazz
       * @return
       */
      public static <T> T obj2pojo(Object obj, Class<T> clazz) {
          return objectMapper.convertValue(obj, clazz);
      }
  }
  