Converter作为EasyExcel中针对读取excel或者写入excel的时候，用于格式转换的问题

    只需要实现Converter接口方法即可

    1. public interface Converter<T> {
    3.     /**
    4.      * Back to object types in Java
    5.      *
    6.      * @return Support for Java class
    7.      */
    8.     Class supportJavaTypeKey();
    10.     /**
    11.      * Back to object enum in excel
    12.      *
    13.      * @return Support for {@link CellDataTypeEnum}
    14.      */
    15.     CellDataTypeEnum supportExcelTypeKey();
    17.     /**
    18.      * Convert excel objects to Java objects
    19.      *
    20.      * @param cellData
    21.      *            Excel cell data.NotNull.
    22.      * @param contentProperty
    23.      *            Content property.Nullable.
    24.      * @param globalConfiguration
    25.      *            Global configuration.NotNull.
    26.      * @return Data to put into a Java object
    27.      * @throws Exception
    28.      *             Exception.
    29.      */
    30.     T convertToJavaData(CellData cellData, ExcelContentProperty contentProperty,
    31.         GlobalConfiguration globalConfiguration) throws Exception;
    33.     /**
    34.      * Convert Java objects to excel objects
    35.      *
    36.      * @param value
    37.      *            Java Data.NotNull.
    38.      * @param contentProperty
    39.      *            Content property.Nullable.
    40.      * @param globalConfiguration
    41.      *            Global configuration.NotNull.
    42.      * @return Data to put into a Excel
    43.      * @throws Exception
    44.      *             Exception.
    45.      */
    46.     CellData convertToExcelData(T value, ExcelContentProperty contentProperty, GlobalConfiguration globalConfiguration)
    47.         throws Exception;
    48. }

    其中convertToJavaData用于读取excel的时候自定义转换
    convertToExcelData用于写入excel的时候进行自定义转换