附加：mybatis配置文件
<?xml version="1.0" encoding="UTF-8" ?> <!DOCTYPE configuration PUBLIC "-//mybatis.org//DTD Config 3.0//EN" "http://mybatis.org/dtd/mybatis-3-config.dtd"> <configuration> <!-- 加载Src下的配置文件 --> <properties resource="db.properties"/> <!--别名机制--> <typeAliases> <typeAlias type="com.cn.entity.User" alias="user"/> </typeAliases> <!-- 连接数据库 --> <environments default="mysql_development"> <environment id="mysql_development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="${driverClass}"/> <property name="url" value="${jdbcUrl}"/> <property name="username" value="${user}"/> <property name="password" value="${password}"/> </dataSource> </environment> <!-- 连接Oracle数据库 --> <environment id="oracle_development"> <transactionManager type="JDBC"/> <dataSource type="POOLED"> <property name="driver" value="oracle.jdbc.driver.OracleDriver"/> <property name="url" value="jdbc:oracle:thin:localhost:1521:orcl"/> <property name="username" value="${user}"/> <property name="password" value="${password}"/> </dataSource> </environment> </environments> <!-- 加载映射文件 --> <mappers> <mapper resource="com/cn/entity/mybatisUserMapper.xml"/> </mappers> </configuration>
附加：测试文件
package com.cn.test; import com.cn.entity.User; import com.cn.utils.MyBatisUtil; import org.apache.ibatis.session.SqlSession; import java.util.Date; import java.util.List; public class TestApp { public static void main(String[] args) { try { /* 加载资源的一种方式： InputStream in = Resources.getResourceAsStream("mybatis.xml"); //创建SqlSessionFactory SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(in); SqlSession sqlSession = sqlSessionFactory.openSession(); System.out.println(sqlSession); */ SqlSession sqlSession = MyBatisUtil.getSqlSession(); User u = new User(); u.setId(22); u.setAddress("湖南"); u.setBirthday(new Date()); u.setSex("女"); u.setUsername("No"); sqlSession.insert("com.cn.entity.User.add",u); List<User> list = sqlSession.selectList("com.cn.entity.User.findAll"); for(User u1 :list){ System.out.println(u1); } } catch (Exception e) { e.printStackTrace(); } } } /* * User{id=1, username='zhangsan', birthday=Mon Feb 05 00:00:00 CST 2018, sex='男', address='湖南'} User{id=2, username='rose', birthday=Thu Mar 08 00:00:00 CST 2018, sex='女', address='东莞'} User{id=3, username='black', birthday=Fri Feb 19 00:00:00 CST 2021, sex='男', address='深圳'} User{id=4, username='pink_girl', birthday=Sat Aug 24 00:00:00 CST 2019, sex='女', address='changsan'} User{id=8, username='heheh', birthday=Sat Aug 24 00:00:00 CST 2019, sex='女', address='huana'} User{id=22, username='No', birthday=Thu Jun 04 00:00:00 CST 2020, sex='女', address='湖南'}*/
1 映射文件中传递的参数是 对象类型：取值的方式如下
<?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.cn.entity.User" >
<insert id="add" parameterType="user"> <!--传递的是一个对象类型，取值时直接写属性即可--> insert into user(id,username,birthday,sex,address) values (#{id},#{username},#{birthday},#{sex},#{address}); </insert> </mapper>
测试代码：
SqlSession sqlSession = MyBatisUtil.getSqlSession(); User u = new User(); u.setId(22); u.setAddress("湖南"); u.setBirthday(new Date()); u.setSex("女"); u.setUsername("No"); sqlSession.insert("com.cn.entity.User.add",u); sqlSession.commit();
2 映射文件中传递的参数是 基本数据类型：取值的方式如下 ， {}里面的变量名可以随意写
<!--查询根据id--> <select id="findbyid" parameterType="int" resultType="user"> select * from user where id = #{id}; </select>
测试代码
User u = sqlSession.selectOne("com.cn.entity.User.findbyid", 8);
3 映射文件中传递的参数是 Map：取值的方式如下
Map<String ,Object> map = new HashMap<String,Object>(); map.put("keyname","1"); map.put("key1","2");
User uu = sqlSession.selectOne("com.cn.entity.User.findbymap",map);
<!-- 传入map时直接取map的key的名字即可 --> <select id="findbymap" parameterType="map" resultType="user"> select * from user where id = #{keyname}; </select>
4 映射文件中传递的参数是 List：取值的方式如下
XML语句： <select id="findByRidAndType" resultMap="entryResource" parameterType="list"> SELECT * FROM t_entry_resource a WHERE <foreach collection="list" index="index" item="entryResources" open="(" close=")" separator="or">
<!--拼接的sql语句 相当与 select * from t_entry_resource where type = ? and resource_id = ? -->
( `type`=#{entryResources.type} and resource_id=#{entryResources.resourceId} ) </foreach> </select>
表结构
MySQL [test]> select * from t_entry_resource;
+----+-------------+------+----------+--------+--------+---------------------+
| id | resource_id | type | title | banner | icon | add_date |
+----+-------------+------+----------+--------+--------+---------------------+
| 11 | 6 | 14 | 分类 | 1.jpg | 2.jpg | 2017-11-17 11:22:30 |
| 12 | 3 | 1 | 测试12 | 3.jpg | 4.jpg | 2017-11-17 11:22:30 |
| 13 | 653 | 1 | 测试34 | 5.jpg | 6.jpg | 2017-11-20 02:32:26 |
| 14 | 1 | 1 | 测试5 | 7.jpg | 8.jpg | 2017-11-20 02:32:51 |
| 15 | 3942 | 3 | 测试6 | 9.jpg | 10.jpg | 2017-11-20 02:34:27 |
+----+-------------+------+----------+--------+--------+---------------------+4. foreach的几种用法
list集合
(1) select count(*) from users id in (x1,x2,x3,...)
<select id="countByUserList" resultType="int" parameterType="list"> select count(*) from users <where> id in <foreach item="item" collection="list" separator="," open="(" close=")" index=""> #{item.id, jdbcType=NUMERIC} </foreach> </where> </select>
(2) select count(*) from key_cols where col_a = ? AND col_b = ?
<select id="sel_key_cols" resultType="int"> select count(*) from key_cols where <foreach item="item" index="key" collection="map" open="" separator="AND" close=""> ${key} = #{item} </foreach> </select>
list集合中的对象
(3) select * from t_news n where n.tags like ? or n.tags like ?
<select id="selectTestForEach" parameterType="News" resultMap="NewsResultMapper"> select * from t_news n where <foreach collection="listTag" index="index" item="tag" open="" separator="or" close=""> n.tags like '%'||#{tag}||'%' </foreach> <select>
参考文献：
https://www.cnblogs.com/coderzhw/p/11094300.html