（一）先配置datasource.properties配置文件：（此步可省略）
jdbc.driver=com.mysql.jdbc.Driver jdbc.url=jdbc:mysql://localhost:3306/wode?useUnicode=true&characterEncoding=UTF-8 jdbc.username=root jdbc.password=admin
（二）配置SqlMapConfig.xml
<?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> <properties resource="datasource.properties"></properties> <typeAliases> <package name="com.wode.pojo"/> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </dataSource> </environment> </environments> <mappers> <package name="com/wode/mapper"/> </mappers> </configuration>
（三）创建自己的工具类：
package com.wodo.util; import java.io.IOException; import java.io.InputStream; import org.apache.ibatis.io.Resources; import org.apache.ibatis.session.SqlSession; import org.apache.ibatis.session.SqlSessionFactory; import org.apache.ibatis.session.SqlSessionFactoryBuilder; public class DbUtil { private static SqlSessionFactory sessionFactory; static{ InputStream in= null; try { in=Resources.getResourceAsStream("SqlMapConfig.xml"); sessionFactory=new SqlSessionFactoryBuilder().build(in); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); }finally { if(in != null){ try { in.close(); } catch (IOException e) { // TODO Auto-generated catch block e.printStackTrace(); } } } } public static SqlSession getSession(){ return sessionFactory.openSession(); } }
（四）导入相关jar包
（五）mapper中xml的配置
5.1：一对一
<?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.wode.mapper.UserInfoMapper"> <resultMap type="UserInfo" id="UserInfo"> <id property="infoId" javaType="int" column="info_id" /> <result javaType="java.lang.String" property="nickName" column="nickname" /> </resultMap> <resultMap type="UserInfo" id="UserInfoWithUser"> <id property="infoId" javaType="int" column="info_id" /> <result javaType="java.lang.String" property="nickName" column="nickname" /> <association property="user" column="user_id" javaType="int" select="com.wode.mapper.UserMapper.findUserById"></association> <!-- 这里我们通过mapper识别符找到userMapper中的findUserById，其实是执行了两次 --> </resultMap> <!-- 单表查询info数据 --> <select id="findUserInfoById" resultMap="UserInfo" parameterType="int"> select * from userinfo where info_id=#{id} </select> <!-- 多表1对1关系查询数据 --> <select id="findInfoAndUserById" resultMap="UserInfoWithUser" parameterType="int"> select * from userinfo where info_id=#{id} </select> </mapper>
<?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.wode.mapper.UserMapper"> <resultMap id="userMap" type="User" > <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> </resultMap> <resultMap id="userAndInfo" type="User" > <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> <association property="info" column="user_id" javaType="UserInfo" select="com.wode.mapper.UserInfoMapper.findUserInfoById"></association> </resultMap> <insert id="addUser" parameterType="User" useGeneratedKeys="true"> insert into users(user_name,user_pwd) values(#{user.userName},#{user.userPwd}) </insert> <select id="findUserById" resultMap="userMap" parameterType="int"> select * from users where user_id=#{id} </select> <select id="findUserAndInfoById" resultMap="userAndInfo" parameterType="int"> select * from users where user_id=#{id} </select> </mapper>
5.2 一对多：
<?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.wode.mapper.UserInfoMapper"> <resultMap type="UserInfo" id="UserInfo"> <id property="infoId" javaType="int" column="info_id" /> <result javaType="java.lang.String" property="nickName" column="nickname" /> </resultMap> <resultMap type="UserInfo" id="UserInfoAndUser"> <id property="infoId" javaType="int" column="info_id" /> <result javaType="java.lang.String" property="nickName" column="nickname" /> <association property="user" column="user_id" javaType="int" select="com.wode.mapper.UserMapper.findUserById"></association> </resultMap> <!-- 单表查询info数据 --> <select id="findUserInfoById" resultMap="UserInfo" parameterType="int"> select * from userinfo where info_id=#{id} <!-- 这里会有问题出现吗？注意查询条件？ --> </select> <select id="findUserInfoById2" resultMap="UserInfo" parameterType="int"> select * from userinfo where user_id=#{id} </select> <!-- 多对1查询 --> <select id="findUserInfoAndUser" resultMap="UserInfoAndUser" parameterType="int"> select * from userinfo where info_id=#{id} </select> </mapper>
<?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.wode.mapper.UserMapper"> <resultMap id="userMap" type="User" > <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> </resultMap> <!-- 连表查询 --> <resultMap id="userandInfo" type="User" > <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> <collection property="info" column="user_id" select="com.wode.mapper.UserInfoMapper.findUserInfoById2"></collection> </resultMap> <insert id="addUser" parameterType="User" useGeneratedKeys="true"> insert into users(user_name,user_pwd) values(#{user.userName},#{user.userPwd}) </insert> <select id="findUserById" resultMap="userMap" parameterType="int"> select * from users where user_id=#{id} </select> <!-- 一对多查询 --> <select id="findUserAndInfoById" resultMap="userandInfo" parameterType="int"> select * from users where user_id=#{id} </select> </mapper>
5.3：多对多
<?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.wode.mapper.CourseMapper"> <resultMap type="Course" id="UserAndCourse"> <id property="id" column="course_id" javaType="int"></id> <result property="code" column="course_code" javaType="java.lang.String" /> <result property="name" column="course_name" javaType="java.lang.String" /> <collection property="users" column="course_id" select="findByUser"></collection> </resultMap> <resultMap type="Course" id="courseMap"> <id property="id" column="course_id" javaType="int"></id> <result property="code" column="course_code" javaType="java.lang.String" /> <result property="name" column="course_name" javaType="java.lang.String" /> </resultMap> <select id="findCourse" resultMap="courseMap" parameterType="int"> select * from course where course_id=#{id} </select> <select id="findUserAndCourse" resultMap="UserAndCourse" parameterType="int"> select * from course where course_id=#{id} </select> <select id="findByUser" parameterType="int" resultMap="com.wode.mapper.UserMapper.userMap"> select * from users where user_id in (select user_id from users_course where course_id=#{id}) </select> </mapper>
<?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.wode.mapper.UserMapper"> <resultMap id="userMap" type="User" > <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> <result property="userType" column="user_type" javaType="int"/> </resultMap> <resultMap type="User" id="userAndCourse"> <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String"/> <result property="userPwd" column="user_pwd" javaType="java.lang.String"/> <result property="userType" column="user_type" javaType="int"/> <collection property="courses" column="user_id" select="findByCourse"></collection> </resultMap> <insert id="addUser" parameterType="User" keyProperty="user.userId" useGeneratedKeys="true"> insert into users values(null,#{user.userName},#{user.userPwd},#{user.userType}) </insert> <!-- 得到刚才插入数据库自增长的主键值 --> <delete id="delById" parameterType="Integer"> delete from users where user_id=#{id} </delete> <update id="updateUserById" parameterType="String"> <!-- id为1的数据的名字改为用户需要的 --> update users set user_name=#{name} where user_id=1 </update> <select id="getUserById" parameterType="Integer" resultMap="userMap" > select * from users where user_id=#{id} </select> <select id="getAllUser" resultMap="userMap" > select * from users </select> <!--many to many--> <select id="findUserAndCourse" parameterType="int" resultMap="userAndCourse"> select * from users where user_id=#{id} </select> <select id="findByCourse" parameterType="int" resultMap="com.wode.mapper.CourseMapper.courseMap"> select * from course where course_id in (select course_id from users_course where user_id=#{id}) </select> </mapper>
5.4：动态sql
<?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.wode.mapper.ScoreMapper"> <sql id="score">id,name,age,className</sql> <resultMap type="Score" id="scoreMap"> <id column="id" javaType="int" property="id"/> <result column="name" property="name" javaType="java.lang.String"/> <result column="age" property="age" javaType="int"/> <result column="className" property="className" javaType="java.lang.String"/> <result column="java" property="java" javaType="int"/> <result column="web" property="web" javaType="int"/> <result column="mysql" property="mysql" javaType="int"/> </resultMap> <!-- 测试sql标签 的使用 --> <select id="findScoreById" parameterType="java.util.Map" resultMap="scoreMap"> select <include refid="score"/> from score where id=#{id} and java=#{java} </select> <!-- 根据if语句对数据结果做筛选 --> <select id="searchStudent" parameterType="java.util.Map" resultMap="scoreMap"> select * from score where 1=1 <if test="java!=null"> and java >=#{java} </if> <if test="web!=null"> and web >=#{web} </if> <if test="mysql!=null"> and mysql >=#{mysql} </if> </select> <!-- choose 对某科目的及格学生做查询 --> <select id="searchStudent2" parameterType="java.lang.String" resultMap="scoreMap"> select * from score <choose> <when test="course=='java'"> where java >=60 </when> <when test="course=='web'"> where web >=60 </when> <otherwise> where mysql >=60 </otherwise> </choose> </select> <!-- <where>条件使用 <select id="searchStudent" parameterType="java.util.Map" resultMap="scoreMap"> select * from score <where> <if test="java!=null"> and java >=#{java} </if> <if test="web!=null"> and web >=#{web} </if> <if test="mysql!=null"> and mysql >=#{mysql} </if> </where> </select> --> <!-- trim <select id="searchStudent" parameterType="java.util.Map" resultMap="scoreMap"> select * from score <trim prefix="where" prefixOverrides="and|or"> <if test="java!=null"> and java >=#{java} </if> <if test="web!=null"> and web >=#{web} </if> <if test="mysql!=null"> and mysql >=#{mysql} </if> </trim> </select> --> <!-- 测试set --> <update id="updateScore" parameterType="java.util.Map"> update score <set> <if test="java != null"> java = #{java}, </if> <if test="web != null"> web = #{web}, </if> <if test="mysql != null"> mysql = #{mysql} </if> </set> where id = #{id} </update> </mapper>
5.5:foreach
<?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.wode.mapper.UserMapper"> <resultMap id="userMap" type="User"> <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String" /> <result property="userPwd" column="user_pwd" javaType="java.lang.String" /> <result property="userType" column="user_type" javaType="int" /> </resultMap> <select id="getUserById" parameterType="Integer" resultMap="userMap"> select * from users where user_id=#{id} </select> <!--1:collection要循环的集合 item：集合中的一个元素 open：以什么开始 close：以什么结束separator：循环内容之间以什么分隔 --> <select id="findUser" parameterType="java.util.Map" resultMap="userMap"> select * from users <where> user_id in <foreach collection="usersId" item="userId" separator="," open="(" close=")" index=""> #{userId} </foreach> </where> </select> </mapper>
5.6:二级缓存（sqlsessionFatory）
需在sqlMapconfig.xml中配置：
<settings> <setting name="cacheEnabled" value="true" /> </settings>
在映射.xml中配置：
<cache />
测试：
public class UserService { public static void main(String[] args) { SqlSession session = DbUtil.getSession(); UserMapper mapper = session.getMapper(UserMapper.class); mapper.getUserById(1); //session.close(); 1级别关闭之后才写入了二级缓存，如果这样我们不关闭session会这么样呢？-执行了两次 SqlSession session2 = DbUtil.getSession(); UserMapper mapper2 = session2.getMapper(UserMapper.class); mapper2.getUserById(1); } }
如：
<?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> <properties resource="datasource.properties"></properties> <settings> <setting name="cacheEnabled" value="true" /> </settings> <!-- 将我们的pojo注册到配置文件 --> <typeAliases> <package name="com.wode.pojo" /> </typeAliases> <environments default="development"> <environment id="development"> <transactionManager type="JDBC" /> <dataSource type="POOLED"> <property name="driver" value="${jdbc.driver}" /> <property name="url" value="${jdbc.url}" /> <property name="username" value="${jdbc.username}" /> <property name="password" value="${jdbc.password}" /> </dataSource> </environment> </environments> <mappers> <package name="com/wode/mapper" /> </mappers> </configuration>
<?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.wode.mapper.UserMapper"> <cache /> <resultMap id="userMap" type="User"> <id property="userId" column="user_id" javaType="int"></id> <result property="userName" column="user_name" javaType="java.lang.String" /> <result property="userPwd" column="user_pwd" javaType="java.lang.String" /> <result property="userType" column="user_type" javaType="int" /> </resultMap> <select id="getUserById" parameterType="Integer" resultMap="userMap" > select * from users where user_id=#{id} </select> </mapper>
5.7：继承
<?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.wode.mapper.PetMapper"> <resultMap id="petMap" type="PetBean"> <id property="id" column="pet_id" javaType="int"/> <result property="name" column="f_name" javaType="java.lang.String"/> <discriminator column="f_type" javaType="java.lang.String"> <case value="dog" resultType="DogBean"> <result property="boneNum" column="f_bonenum" javaType="int"/> </case> <case value="duck" resultType="DuckBean"> <result property="fishNum" column="f_fishnum" javaType="int"/> </case> <case value="cat" resultType="CatBean"> <result property="fishNum" column="f_fishnum" javaType="int"/> <result property="mouseNum" column="f_mousenum" javaType="int"/> </case> </discriminator> </resultMap> <select id="getAllPet" resultMap="petMap"> select * from pet </select> <select id="getAllCat" resultMap="petMap"> select * from pet where f_type='cat' </select> </mapper>
el常用判断表达式：
==、eq、//相等
!=、ne、// 不相等
<、lt、//小于
>、gt、//大于
<=、ge、//小于等于
>=、le。//大于等于