MyBatis中${}和#{}传参的区别 详解mybatis #{}和${}的区别、传参、基本语法
wutongyuWxc 人气:01 #{}和${}的区别、及注入问题
(1) 区别: 首先清楚一点,动态 SQL 是 mybatis 的强大特性之一,在 mapper 中定义的参数传到 xml 中之后,在查询之前 mybatis 会对其进行动态解析,#{} 和 ${} 在预编译中的处理是不一样的: 例如:select * from t_user where userName = #{name}; #{}预编译:用一个占位符 ? 代替参数:select * from t_user where userName = ? #{}预编译:会将参数值一起进行编译:select * from t_user where userName = 'zhangsan' (2) 使用场景: 一般情况首选#{},因为这样能避免sql注入;如果需要传参 动态表名、动态字段名时,需要使用${} 比如:select * from ${tableName} where id > #{id}; (3) SQL注入问题: 举个例子,如果使用${}出现的注入问题: select * from ${tableName}; 如果传参 t_user;delete from t_user,则预编译后的sql如下,将会导致系统不可用: select * from t_user;delete from t_user; (4) like 语句防注入: 使用concat函数: select * from t_user where name like concat('%', #{name}, '%')
2 mybatis几种传参方式
非注解: (1)单参数: public User getUserByUuid(String uuid); <select id="getUserByUuid" resultMap="BaseResultMap" parameterType="Object"> SELECT * FROM t_user WHERE uuid = #{uuid} </select> (2)多参数 public User getUserByNameAndPass(String name,String pass); <select id="getUserByNameAndPass" resultMap="BaseResultMap" parameterType="Object"> SELECT * FROM t_user WHERE t_name = #{0} and t_pass = #{1} </select> (3)Map参数 public User getUserByMap(Map<String,Object> map); <select id="getUserByMap" resultMap="BaseResultMap" parameterType="java.util.Map"> SELECT * FROM t_user WHERE t_name = #{name} and t_pass = #{pass} </select> (4)实体对象参数 public int updateUser(User user); <select id="updateUser" resultMap="BaseResultMap" parameterType="Object"> update t_user set t_name = #{name}, t_pass = #{pass} where uuid=#{uuid} </select> (4)List集合参数 public int batchDelUser(List<String> uuidList); <delete id="batchDelUser" parameterType="java.util.List"> DELETE FROM t_user WHERE uuid IN <foreach collection="list" index="index" item="uuid" open="(" separator="," close=")"> #{uuid} </foreach> </delete> 注解: public List<User> getUserByTime(@Param("startTime")String startTime, @Param("endTime")String endTime); <select id="getUserByTime" resultMap="BaseResultMap" parameterType="Object"> SELECT * from t_user where createTime >= #{startTime} and createTime <= #{endTime} </select>
2 choose when otherwise
//JAVA 代码 public List<Group> getUserRoleRelByUserUuid(@Param("groupUuid") String userUuid,@Param("roleList")List<String> roleUuidList); //SQL SELECT * from user_role where groupUuid=#{groupUuid} <choose> <when test="roleList!=null&&roleList.size()>0"> AND roleUuid IN <foreach collection="roleList" index="index" item="roleUuid" open="(" separator="," close=")"> #{roleUuid} </foreach> </when> <otherwise> AND roleUuid IN ('') </otherwise> </choose>
3 判断字符串相等
//JAVA 代码 public int getOrderCountByParams(Map<String, Object> params); //SQL <select id="getOrderCountByParams" resultType="java.lang.Integer" parameterType="Object"> SELECT count(*) FROM itil_publish_order where 1=1 <if test="timeType == '1'.toString()" > AND create_time >= #{timeStr} </if> <if test="timeType == '2'.toString()" > AND end_time <= #{timeStr} </if> </select> 或者 <if test = 'timeType== "1"'> </if>
4 CONCAT函数实现 模糊匹配
<select id="getMaxSerialCode" resultType="java.lang.String" parameterType="Object"> SELECT count(*) FROM itil_publish_order WHERE serial_code LIKE CONCAT('%',#{codeStr},'%') ORDER BY serial_code DESC LIMIT 1 </select>
5 大于等于、小于等于
//JAVA代码 public List<PublishOrder> getOrderCount(@Param("startTime") String startTime,@Param("startTime")List<String> startTime); //SQL <select id="getOrderCount" resultType="java.lang.String" parameterType="Object"> SELECT * FROM itil_publish_order WHERE createTime >= #{startTime} and <= #{startTime} </select>
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