public class StringTypeHandler implements TypeHandler<Object> {
    private static Logger logger = org.slf4j.LoggerFactory.getLogger(StringTypeHandler.class);

    private static String ISO88591_ENCODE = "ISO8859_1";
    private static String UTF8_ENCODE = "UTF-8";
    private static String GBK_ENCODE = "GBK";

    public void setParameter(PreparedStatement ps, int i, Object parameter, JdbcType jdbcType) throws SQLException {
        try {
            String paramStr = null;
            if (null != parameter) {
                paramStr = (String) parameter;
                if (GBK_ENCODE.equals(getEncode(paramStr))) {
                    if (null != parameter) {
                        ps.setString(i, new String(((String) parameter).getBytes(GBK_ENCODE), ISO88591_ENCODE));
                    }
                }
            }
            else {
                ps.setString(i, (String) parameter);
            }
        } catch (UnsupportedEncodingException e) {
            ps.setString(i, (String) parameter);
            logger.debug("StringTypeHandler encode Exception");
        }
    }

    public Object getResult(ResultSet rs, String columnName) throws SQLException {
        try {
            if (null != rs.getString(columnName)) {
                String columnValue = rs.getString(columnName);
                if (ISO88591_ENCODE.equals(getEncode(columnValue))) {
                    return new String(rs.getString(columnName).getBytes(ISO88591_ENCODE), GBK_ENCODE);
                }
            }
        } catch (UnsupportedEncodingException e) {
            logger.debug("StringTypeHandler encode Exception");
        }
        return rs.getString(columnName);
    }

    public Object getResult(CallableStatement cs, int columnIndex) throws SQLException {
        return cs.getString(columnIndex);
    }

    //返回编码格式
    private String getEncode(String str) {
        String encode = null;
        if (verifyEncode(str, GBK_ENCODE)) {
            encode = GBK_ENCODE;
        } else if (verifyEncode(str, ISO88591_ENCODE)) {
            encode = ISO88591_ENCODE;
        } else if (verifyEncode(str, UTF8_ENCODE)) {
            encode = UTF8_ENCODE;
        } 

        return encode;
    }

    //判断编码格式是否相符
    private boolean verifyEncode(String str, String encode) {
        try {
            if (str.equals(new String(str.getBytes(encode), encode))) {
                return true;
            }
        } catch (UnsupportedEncodingException e) {
            logger.debug("StringTypeHandler encode UnsupportedEncoding");
        }
        return false;
    }

   <typeHandlers>
          <typeHandler javaType="String" jdbcType="VARCHAR"    handler="com.betdemo.interceptor.StringTypeHandler" />
   </typeHandlers>