在项目开发中，mybatis <if> 标签使用广泛，本文讲解if标签的两种使用方式
其一、使用 <if> 标签判断某一字段是否为空
其二、使用 <if> 标签判断传入参数是否相等
具体代码如下
数据库表结构和数据
实体类
package com.demo.bean;
public class Commodity {
private String name;
private String date;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getDate() {
return date;
}
public void setDate(String date) {
this.date = date;
}
@Override
public String toString() {
return "Com [name=" + name + ", date=" + date + "]";
}
}
mapper层
package com.demo.mapper;
import java.util.List;
import org.apache.ibatis.annotations.Mapper;
import org.apache.ibatis.annotations.Param;
import com.demo.bean.Commodity;
@Mapper
public interface CommodityMapper {
List<Commodity> getListByDate(Commodity commodity);
List<Commodity> getListByStartDateAndEndDate(@Param("startDate")String startDate, @Param("endDate")String endDate);
}
mapper.xml文件
<?xml version="1.0" encoding="UTF-8" ?>
<!DOCTYPE mapper PUBLIC "-//mybatis.org//DTD Mapper 3.0//EN" "http://mybatis.org/dtd/mybatis-3-mapper.dtd" >
<mapper namespace="com.demo.mapper.CommodityMapper">
<resultMap id="BaseResultMap" type="com.demo.bean.Commodity">
<id column="name" property="name" jdbcType="VARCHAR" />
<result column="date" property="date" jdbcType="VARCHAR" />
</resultMap>
<select id="getListByDate" resultMap="BaseResultMap">
select * from commodity where 1 = 1
<if test="date != null and date != ''">
and date = #{date}
</if>
</select>
<select id="getListByStartDateAndEndDate" resultMap="BaseResultMap">
select * from commodity where 1 = 1
<if test="#{startDate}.toString() != #{endDate}.toString()">
and date between #{startDate} and #{endDate}
</if>
</select>
</mapper>
注意:mybatis 等值判断的 tostring()方法 (上边代码中第二个select中的toString()方法)
controller层
package com.demo.controller;
import java.util.HashMap;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;
import org.springframework.web.bind.annotation.RestController;
import com.demo.bean.Commodity;
import com.demo.mapper.CommodityMapper;
@RestController
public class DemoController {
@Autowired
private CommodityMapper comMapper;
@RequestMapping(value = "/commodity")
public Object commodity() {
Map<String, Object> map = new HashMap<String, Object>();
Commodity com =new Commodity();
com.setDate("2018-10-12");
map.put("res", comMapper.getListByDate(com));
return map;
}
@RequestMapping(value = "/between")
public Object commodityBetween() {
Map<String, Object> map = new HashMap<String, Object>();
map.put("res", comMapper.getListByStartDateAndEndDate("2018-10-09", "2018-10-13"));
return map;
}
}
测试
1、访问 http://localhost:9000/commodity
2、访问 http://localhost:9000/between
