Java – Mybatis when using custom generic typehandler and the bean property name and table’s column are same, select will raise ClassCastException

I am new to Mybatis. Recently I used custom generic typeHander, when the bean property is same with table's column name, select will raise ClassCastException.

Following are configuration

mybatis-configuration.xml

<typeHandlers>
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.WhetherTypeEnum" jdbcType="CHAR"/>
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.SexTypeEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.ArticleTypeEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.EducationLevelEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.ServiceLevelEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.ServiceTypeEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.StaffLevelEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.ArticleStatusEnum" jdbcType="CHAR" />
        <typeHandler handler="com.sut.util.enumerate.mybatis.GenericEnumUserType"
            javaType="com.sut.util.meta.HealthyStatusEnum" jdbcType="CHAR" />
</typeHandlers>

staffMapper.xml

 <resultMap type="com.sut.persist.entity.Staff" id="staff">
    <id property="id" javaType="int" column="id" />
    <result property="staffName" javaType="String" column="STAFF_NAME" />
    <result property="imgPath" javaType="String" column="IMG_PATH" />
    <result property="staffLevel" javaType="com.sut.util.meta.StaffLevelEnum" column="LEVEL"
        typeHandler="com.sut.util.enumerate.mybatis.GenericEnumUserType" jdbcType="CHAR"/>
    <result property="birthDate" javaType="java.util.Date" column="BIRTH_DATE" />
    <result property="address" javaType="String" column="address" />
    <result property="healthyStatus" javaType="com.sut.util.meta.HealthyStatusEnum" column="HEALTHY_STATUS"
        typeHandler="com.sut.util.enumerate.mybatis.GenericEnumUserType" jdbcType="CHAR" />
    <result property="education" column="education" typeHandler="com.sut.util.enumerate.mybatis.GenericEnumUserType" /> 
    <result property="workYears" javaType="integer" column="WORK_YEARS" />
    <result property="selfIntroduction" javaType="String" column="SELF_INTRODUCTION" />
    <result property="cert" javaType="String" column="CERT" />
    <result property="remark" javaType="String" column="REMARK" />
    <result property="serviceType" javaType="com.sut.util.meta.ServiceTypeEnum" column="SERVICE_TYPE"
        typeHandler="com.sut.util.enumerate.mybatis.GenericEnumUserType" /> 
    <result property="mobile" javaType="String" column="MOBILE" />
    <result property="qqNumber" javaType="String" column="QQ_NUMBER" />
    <result property="webchatNumber" javaType="String" column="WEBCHAT_NUMBER" />
    <result property="webchatQrcode" javaType="String" column="WEBCHAT_QRCODE" />   
</resultMap>

<!-- query user by id -->
<select id="getById" parameterType="long"  resultMap="staff">
    select
        staff_id,
        staff_name,
        img_path,
        level as staffLevel,
        birth_date,
        address,
        healthy_status as healthyStatus,
        education as education, 
        work_years,
        self_introduction,
        cert,
        remark,
        service_type as serviceType,
        mobile,
        qq_number,
        webchat_number,
        webchat_qrcode
    from bbs_staff where staff_id = #{id}

Staff.java:

public class Staff implements java.io.Serializable {

    private static final long serialVersionUID = 1L;

    private long id;
    private String staffName;
    private String imgPath;
    private StaffLevelEnum staffLevel;
    private java.util.Date birthDate;
    private java.lang.String address;
    private HealthyStatusEnum healthyStatus;
    private EducationLevelEnum educationLevel;
    private int workYears;
    private String selfIntroduction;
    private String cert;
    private String remark;
    private ServiceTypeEnum serviceType;
    private String mobile;
    private String qqNumber;
    private String webchatNumber;
    private String webchatQrcode;

    /**
     * default Constructor
     */
    public Staff() {
        super();
    }


    public long getId() {
        return id;
    }


    public void setId(long id) {
        this.id = id;
    }


    public String getStaffName() {
        return staffName;
    }

    public void setStaffName(String staffName) {
        this.staffName = staffName;
    }

    public String getImgPath() {
        return imgPath;
    }

    public void setImgPath(String imgPath) {
        this.imgPath = imgPath;
    }


    public StaffLevelEnum getStaffLevel() {
        return staffLevel;
    }


    public void setStaffLevel(StaffLevelEnum staffLevel) {
        this.staffLevel = staffLevel;
    }


    public java.util.Date getBirthDate() {
        return birthDate;
    }

    public void setBirthDate(java.util.Date birthDate) {
        this.birthDate = birthDate;
    }

    public java.lang.String getAddress() {
        return address;
    }

    public void setAddress(java.lang.String address) {
        this.address = address;
    }

    public HealthyStatusEnum getHealthyStatus() {
        return healthyStatus;
    }

    public void setHealthyStatus(HealthyStatusEnum healthyStatus) {
        this.healthyStatus = healthyStatus;
    }

    public EducationLevelEnum getEducationLevel() {
        return educationLevel;
    }


    public void setEducationLevel(EducationLevelEnum educationLevel) {
        this.educationLevel = educationLevel;
    }

    public int getWorkYears() {
        return workYears;
    }

    public void setWorkYears(int workYears) {
        this.workYears = workYears;
    }


    public String getSelfIntroduction() {
        return selfIntroduction;
    }


    public void setSelfIntroduction(String selfIntroduction) {
        this.selfIntroduction = selfIntroduction;
    }

    public String getCert() {
        return cert;
    }

    public void setCert(String cert) {
        this.cert = cert;
    }

    public String getRemark() {
        return remark;
    }

    public void setRemark(String remark) {
        this.remark = remark;
    }

    public ServiceTypeEnum getServiceType() {
        return serviceType;
    }

    public void setServiceType(ServiceTypeEnum serviceType) {
        this.serviceType = serviceType;
    }

    public String getMobile() {
        return mobile;
    }

    public void setMobile(String mobile) {
        this.mobile = mobile;
    }

    public String getQqNumber() {
        return qqNumber;
    }

    public void setQqNumber(String qqNumber) {
        this.qqNumber = qqNumber;
    }

    public String getWebchatNumber() {
        return webchatNumber;
    }

    public void setWebchatNumber(String webchatNumber) {
        this.webchatNumber = webchatNumber;
    }

    public String getWebchatQrcode() {
        return webchatQrcode;
    }

    public void setWebchatQrcode(String webchatQrcode) {
        this.webchatQrcode = webchatQrcode;
    }

    @Override
    public String toString() {
        return MoreObjects.toStringHelper(Staff.class)
                .add("id", id)
                .add("staffName", staffName)
                .add("imgPath", imgPath)
                .add("level", staffLevel)
                .add("birthDate", birthDate)
                .add("address", address)
                .add("healthyStatus", healthyStatus)
                .add("education", educationLevel)
                .add("workYears", workYears)
                .add("selfIntroduction", selfIntroduction)
                .add("cert", cert)
                .add("remark", remark)
                .add("serviceType", serviceType)
                .add("mobile", mobile)
                .add("qqNumber", qqNumber)
                .add("webChatNumber", webchatNumber)
                .add("webChatQrcode", webchatQrcode)
                .toString();
    }

}

com.sut.util.enumerate.mybatis.GenericEnumUserType:

public class GenericEnumUserType<E extends StringEnumTypeImp> extends BaseTypeHandler<E>{

    private static final Logger LOG = LoggerFactory.getLogger(GenericEnumUserType.class);

    //mybatis will pass actual class when constructing TypeHandler
    private Class<E> type;

    private static final String fromStringCode = "fromStringCode";

    public GenericEnumUserType(Class<E> type){
        Preconditions.checkNotNull(type, "Type argument cannot be null");
        this.type = type;
    }

    /**
     * @see org.apache.ibatis.type.BaseTypeHandler#setNonNullParameter(java.sql.PreparedStatement, int, java.lang.Object, org.apache.ibatis.type.JdbcType)
     */
    @Override
    public void setNonNullParameter(PreparedStatement ps, int i, StringEnumTypeImp parameter, JdbcType jdbcType) throws SQLException {
        ps.setString(i, parameter.getStoreValue());
    }

    /**
     * getResult and use reflect 
     * @see org.apache.ibatis.type.BaseTypeHandler#getNullableResult(java.sql.ResultSet, java.lang.String)
     */
    @Override
    @SuppressWarnings("unchecked")
    public E getNullableResult(ResultSet rs, String columnName) throws SQLException {
        LOG.info("return type is : {}", type);
        String storeValue =  rs.getString(columnName);
        Preconditions.checkNotNull(type, "Type argument cannot be null");
        try {
            Method fromMethod = type.getMethod(fromStringCode, String.class);
            return (E) fromMethod.invoke(null, storeValue);
        } catch (IllegalAccessException | NoSuchMethodException | SecurityException | IllegalArgumentException | InvocationTargetException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * 
     * @see org.apache.ibatis.type.BaseTypeHandler#getNullableResult(java.sql.ResultSet, int)
     */
    @SuppressWarnings("unchecked")
    @Override
    public E getNullableResult(ResultSet rs, int columnIndex) throws SQLException {
        LOG.info("return type is {}", type);
        String storeValue =  rs.getString(columnIndex);
        Preconditions.checkNotNull(type, "Type argument cannot be null");
        try {
            Method fromMethod = type.getMethod(fromStringCode, String.class);
            return (E) fromMethod.invoke(null, storeValue);
        } catch (IllegalAccessException | NoSuchMethodException | SecurityException | IllegalArgumentException | InvocationTargetException e) {
            e.printStackTrace();
        }
        return null;
    }

    /**
     * not used
     * @see org.apache.ibatis.type.BaseTypeHandler#getNullableResult(java.sql.CallableStatement, int)
     */
    @Override
    public E getNullableResult(CallableStatement cs, int columnIndex) throws SQLException {
        try {
            return type.newInstance();
        } catch (InstantiationException | IllegalAccessException e) {
            e.printStackTrace();
        }
        return null;
    }

}

when call the getById method, it will raise the Exception:

Struts has detected an unhandled exception:

Messages:   
java.lang.ClassCastException@6f26a5f5
Could not set property 'education' of 'class com.sut.persist.entity.Staff' with value 'com.sut.util.meta.HealthyStatusEnum@3b554a50' Cause: java.lang.IllegalArgumentException: java.lang.ClassCastException@6f26a5f5
nested exception is org.apache.ibatis.reflection.ReflectionException: Could not set property 'education' of 'class com.sut.persist.entity.Staff' with value 'com.sut.util.meta.HealthyStatusEnum@3b554a50' Cause: java.lang.IllegalArgumentException: java.lang.ClassCastException@6f26a5f5 

The mybatis docs said when using Generic TypeHandler , it will get By JavaType, even the the jdbcType is null, it will get the right TypeHandler. I checked configurations three times, and debuged the source code. Then I figure out that ResultSetWrapper will seprated columns to mappedColumns and UnmappedColumns, the unmappedColumns will return the right TypeHandler, as mappedColumns won't. I'm curious why does this happen. Is this a bug or my configurations are not correct.

Environments:
Mybatis : 3.4.1
MySQL : 5.6

Any help will be appreciated!