1 #{}和${}的区别、及注入问题
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( 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
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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
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//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
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//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
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<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
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//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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原文链接:https://blog.csdn.net/wutongyuWxc/article/details/84584239