code: public Convertor getConvertor(Class src, Class dest) {
          if (src == dest) {
              // 对相同类型的直接忽略，不做转换
              return null;
          }
  
          // 按照src->dest来取映射
          Convertor convertor = repository.getConvertor(src, dest);
  
          // 处理下Array|Collection的映射
          // 如果src|dest是array类型，取一下Array.class的映射，因为默认数组处理的注册直接注册了Array.class
          boolean isSrcArray = src.isArray();
          boolean isDestArray = dest.isArray();
          if (convertor == null && src.isArray() && dest.isArray()) {
              convertor = arrayToArray;
          } else {
              boolean isSrcCollection = Collection.class.isAssignableFrom(src);
              boolean isDestCollection = Collection.class.isAssignableFrom(dest);
              if (convertor == null && isSrcArray && isDestCollection) {
                  convertor = arrayToCollection;
              }
              if (convertor == null && isDestArray && isSrcCollection) {
                  convertor = collectionToArray;
              }
              if (convertor == null && isSrcCollection && isDestCollection) {
                  convertor = collectionToCollection;
              }
          }
  
          // 如果dest是string，获取一下object->string. (系统默认注册了一个Object.class -> String.class的转化)
          if (convertor == null && dest == String.class) {
              if (src.isEnum()) {// 如果是枚举
                  convertor = enumToString;
              } else { // 默认进行toString输出
                  convertor = objectToString;
              }
          }
  
          // 如果是其中一个是String类
          if (convertor == null && src == String.class) {
              if (commonTypes.containsKey(dest)) { // 另一个是Common类型
                  convertor = stringToCommon;
              } else if (dest.isEnum()) { // 另一个是枚举对象
                  convertor = stringToEnum;
              }
          }
  
          // 如果src/dest都是Common类型，进行特殊处理
          if (convertor == null && commonTypes.containsKey(src) && commonTypes.containsKey(dest)) {
              convertor = commonToCommon;
          }
  
          return convertor;
      }
docs: 根据class获取对应的convertor
  
  @return