mybatis 遇到空串无法判断

sql 语句中对传入的关键字进行判断，如果是空或者空串则不进入条件

   <if test="query.keyword !=null and query.keyword != ''">
             and   (t.id like concat('%',#{query.keyword},'%')
             or
             t.trading_account_id like concat('%',#{query.keyword},'%')
             or
             u.fx_code like concat('%',#{query.keyword},'%')
             or
             a.account_name like concat('%',#{query.keyword},'%')
                )
   </if>

而实际上，当传入

 数据库执行情况

==>  Preparing: SELECT count(0) FROM t_trading_announcement t LEFT JOIN t_trading_account a ON a.id = t.trading_account_id LEFT JOIN t_user u ON u.id = a.user_id 
　　　　WHERE 1 = 1 AND (t.id LIKE concat('%', ?, '%') OR t.trading_account_id LIKE concat('%', ?, '%') OR u.fx_code LIKE concat('%', ?, '%') OR a.account_name LIKE concat('%', ?, '%')) 
==> Parameters: ''(String), ''(String), ''(String), ''(String)
<==    Columns: count(0)
<==        Row: 0
<==      Total: 1

判断失效，原因还没找到。暂时代码中判断

如果传入 “” ，则可以通过判断

如果传入的是 ‘’ ，则接收的参数实际上是 “‘’”