My Batis 的官方定义：MyBatis是支持定制化SQL、存储过程以及高级映射的优秀的持久层框架。MyBatis可以对配置和原生Map使用简单的XML或注解，将接口和Java的POJO映射成数据库中的记录。可以看出，MyBatis是基于一种SQL到POJO的模型，它需要我们提供SQL、映射关系（XML或者注解，目前以XML 为主）和POJO 。与此同时，它还能支持动态SQL，以适应需求的变化，当前MyBatis渐渐成为市场的主流持久框架。MyBatis的配置文件包括两个大的部分，一是基础配置文件，一个是映射文件。在MyBatis中也可以使用注解来实现映射，只是由于功能和可读性的限制，在实际的项目使用得比较少，所以不介绍使用注解配置SQL的方式。
6.2.1 工程文件中添加依赖包：pom.xml
<!-- 导入mybatis依赖包 -->
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.1.1</version>
</dependency>
mybatis-spring-boot-starter依赖：
- 自动检测现有的DataSource
- 创建并注册SqlSessionFactory的实例，该实例使用SqlSessionFactoryBean将该DataSource作为输入进行传递
- 创建并注册从SqlSessionFactory中获取的SqlSessionTemplate的实例。
- 自动扫描您的mappers，将它们链接到SqlSessionTemplate并将其注册到Spring上下文，以便将它们注入到您的bean中。
即当我们引入mybatis-spring-boot-starter之后，只需要在application.properties定义一个DataSource，它会自动创建使用该DataSource的SqlSessionFactoryBean以及SqlSessionTemplate。同时会自动扫描我们指定的mappers，注册到Spring上下文中。
6.2.2 配置数据源
application.properties配置MySQL数据源。
server.servlet.context-path=/gavin
server.port=9001
spring.datasource.driverClassName=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://rm-wz98XXXXuo.mysql.rds.aliyuncs.com:3306/usermng?useUnicode=true&characterEncoding=UTF-8&useSSL=false&serverTimezone=UTC
spring.datasource.username=gavin
spring.datasource.password=gavinpw
注意：现在有些文章中可能存在记述错误的地方。
spring.datasource.driverClassName如果设定为：com.mysql.jdbc.Driver，会引起编译错误，给出的提示中已经说明了修改方法，将ClassName变更为：com.mysql.cj.jdbc.Driver。
Loading class `com.mysql.jdbc.Driver'. This is deprecated. The new driver class is `com.mysql.cj.jdbc.Driver'. The driver is automatically registered via the SPI and manual loading of the driver class is generally unnecessary.
全局配置文件 application.properties中spring.datasource下只配置了数据库地址、连接驱动、账号、密码，默认使用的是HikariDataSource数据源（com.zaxxer.hikari.HikariDataSource）。
6.2.3 使用mybatis-generator-gui自动生成代码
详细使用参考【11.1 使用mybatis-generator-gui自动生成mybatis关联代码】
也可以下载直接编译好的可执行的文件：
1. 生成用户信息代码
package com.gavinbj.confmng.persistence.entity;
import java.io.Serializable;
import java.util.Date;
/**
* UserInfo
* @author gavinbj
*/
public class UserInfo implements Serializable {
private String userId;
/**
* 用户姓名
*/
private String userName;
/**
* 个人介绍
*/
private String introduce;
/**
* 移动电话
*/
private String mobilephone;
/**
* 邮箱
*/
private String email;
/**
* 生日
*/
private Date birthday;
/**
* 性别
*/
private String gender;
private static final long serialVersionUID = 1L;
public String getUserId() {
return userId;
}
public void setUserId(String userId) {
this.userId = userId;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getIntroduce() {
return introduce;
}
public void setIntroduce(String introduce) {
this.introduce = introduce;
}
public String getMobilephone() {
return mobilephone;
}
public void setMobilephone(String mobilephone) {
this.mobilephone = mobilephone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public Date getBirthday() {
return birthday;
}
public void setBirthday(Date birthday) {
this.birthday = birthday;
}
public String getGender() {
return gender;
}
public void setGender(String gender) {
this.gender = gender;
}
@Override
public boolean equals(Object that) {
if (this == that) {
return true;
}
if (that == null) {
return false;
}
if (getClass() != that.getClass()) {
return false;
}
UserInfo other = (UserInfo) that;
return (this.getUserId() == null ? other.getUserId() == null : this.getUserId().equals(other.getUserId()))
&& (this.getUserName() == null ? other.getUserName() == null : this.getUserName().equals(other.getUserName()))
&& (this.getIntroduce() == null ? other.getIntroduce() == null : this.getIntroduce().equals(other.getIntroduce()))
&& (this.getMobilephone() == null ? other.getMobilephone() == null : this.getMobilephone().equals(other.getMobilephone()))
&& (this.getEmail() == null ? other.getEmail() == null : this.getEmail().equals(other.getEmail()))
&& (this.getBirthday() == null ? other.getBirthday() == null : this.getBirthday().equals(other.getBirthday()))
&& (this.getGender() == null ? other.getGender() == null : this.getGender().equals(other.getGender()));
}
@Override
public int hashCode() {
final int prime = 31;
int result = 1;
result = prime * result + ((getUserId() == null) ? 0 : getUserId().hashCode());
result = prime * result + ((getUserName() == null) ? 0 : getUserName().hashCode());
result = prime * result + ((getIntroduce() == null) ? 0 : getIntroduce().hashCode());
result = prime * result + ((getMobilephone() == null) ? 0 : getMobilephone().hashCode());
result = prime * result + ((getEmail() == null) ? 0 : getEmail().hashCode());
result = prime * result + ((getBirthday() == null) ? 0 : getBirthday().hashCode());
result = prime * result + ((getGender() == null) ? 0 : getGender().hashCode());
return result;
}
@Override
public String toString() {
StringBuilder sb = new StringBuilder();
sb.append(getClass().getSimpleName());
sb.append(" [");
sb.append("Hash = ").append(hashCode());
sb.append(", userId=").append(userId);
sb.append(", userName=").append(userName);
sb.append(", introduce=").append(introduce);
sb.append(", mobilephone=").append(mobilephone);
sb.append(", email=").append(email);
sb.append(", birthday=").append(birthday);
sb.append(", gender=").append(gender);
sb.append(", serialVersionUID=").append(serialVersionUID);
sb.append("]");
return sb.toString();
}
}
2. 用户Mapper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.gavinbj.confmng.persistence.mapper.UserInfoMapper">
<resultMap id="BaseResultMap" type="com.gavinbj.confmng.persistence.entity.UserInfo">
<id column="user_id" jdbcType="VARCHAR" property="userId" />
<result column="user_name" jdbcType="VARCHAR" property="userName" />
<result column="introduce" jdbcType="VARCHAR" property="introduce" />
<result column="mobilephone" jdbcType="VARCHAR" property="mobilephone" />
<result column="email" jdbcType="VARCHAR" property="email" />
<result column="birthday" jdbcType="DATE" property="birthday" />
<result column="gender" jdbcType="VARCHAR" property="gender" />
</resultMap>
<sql id="Example_Where_Clause">
<where>
<foreach collection="oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
</when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Update_By_Example_Where_Clause">
<where>
<foreach collection="example.oredCriteria" item="criteria" separator="or">
<if test="criteria.valid">
<trim prefix="(" prefixOverrides="and" suffix=")">
<foreach collection="criteria.criteria" item="criterion">
<choose>
<when test="criterion.noValue">
and ${criterion.condition}
</when>
<when test="criterion.singleValue">
and ${criterion.condition} #{criterion.value}
</when>
<when test="criterion.betweenValue">
and ${criterion.condition} #{criterion.value} and #{criterion.secondValue}
</when>
<when test="criterion.listValue">
and ${criterion.condition}
<foreach close=")" collection="criterion.value" item="listItem" open="(" separator=",">
#{listItem}
</foreach>
</when>
</choose>
</foreach>
</trim>
</if>
</foreach>
</where>
</sql>
<sql id="Base_Column_List">
user_id, user_name, introduce, mobilephone, email, birthday, gender
</sql>
<select id="selectByExample" parameterType="com.gavinbj.confmng.persistence.entity.UserInfoExample" resultMap="BaseResultMap">
select
<if test="distinct">
distinct
</if>
<include refid="Base_Column_List" />
from user_info
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
<if test="orderByClause != null">
order by ${orderByClause}
</if>
<if test="limit != null">
<if test="offset != null">
limit ${offset}, ${limit}
</if>
<if test="offset == null">
limit ${limit}
</if>
</if>
</select>
<select id="selectByPrimaryKey" parameterType="java.lang.String" resultMap="BaseResultMap">
select
<include refid="Base_Column_List" />
from user_info
where user_id = #{userId,jdbcType=VARCHAR}
</select>
<delete id="deleteByPrimaryKey" parameterType="java.lang.String">
delete from user_info
where user_id = #{userId,jdbcType=VARCHAR}
</delete>
<delete id="deleteByExample" parameterType="com.gavinbj.confmng.persistence.entity.UserInfoExample">
delete from user_info
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</delete>
<insert id="insert" parameterType="com.gavinbj.confmng.persistence.entity.UserInfo">
insert into user_info (user_id, user_name, introduce,
mobilephone, email, birthday,
gender)
values (#{userId,jdbcType=VARCHAR}, #{userName,jdbcType=VARCHAR}, #{introduce,jdbcType=VARCHAR},
#{mobilephone,jdbcType=VARCHAR}, #{email,jdbcType=VARCHAR}, #{birthday,jdbcType=DATE},
#{gender,jdbcType=VARCHAR})
</insert>
<insert id="insertSelective" parameterType="com.gavinbj.confmng.persistence.entity.UserInfo">
insert into user_info
<trim prefix="(" suffix=")" suffixOverrides=",">
<if test="userId != null">
user_id,
</if>
<if test="userName != null">
user_name,
</if>
<if test="introduce != null">
introduce,
</if>
<if test="mobilephone != null">
mobilephone,
</if>
<if test="email != null">
email,
</if>
<if test="birthday != null">
birthday,
</if>
<if test="gender != null">
gender,
</if>
</trim>
<trim prefix="values (" suffix=")" suffixOverrides=",">
<if test="userId != null">
#{userId,jdbcType=VARCHAR},
</if>
<if test="userName != null">
#{userName,jdbcType=VARCHAR},
</if>
<if test="introduce != null">
#{introduce,jdbcType=VARCHAR},
</if>
<if test="mobilephone != null">
#{mobilephone,jdbcType=VARCHAR},
</if>
<if test="email != null">
#{email,jdbcType=VARCHAR},
</if>
<if test="birthday != null">
#{birthday,jdbcType=DATE},
</if>
<if test="gender != null">
#{gender,jdbcType=VARCHAR},
</if>
</trim>
</insert>
<select id="countByExample" parameterType="com.gavinbj.confmng.persistence.entity.UserInfoExample" resultType="java.lang.Long">
select count(*) from user_info
<if test="_parameter != null">
<include refid="Example_Where_Clause" />
</if>
</select>
<update id="updateByExampleSelective" parameterType="map">
update user_info
<set>
<if test="record.userId != null">
user_id = #{record.userId,jdbcType=VARCHAR},
</if>
<if test="record.userName != null">
user_name = #{record.userName,jdbcType=VARCHAR},
</if>
<if test="record.introduce != null">
introduce = #{record.introduce,jdbcType=VARCHAR},
</if>
<if test="record.mobilephone != null">
mobilephone = #{record.mobilephone,jdbcType=VARCHAR},
</if>
<if test="record.email != null">
email = #{record.email,jdbcType=VARCHAR},
</if>
<if test="record.birthday != null">
birthday = #{record.birthday,jdbcType=DATE},
</if>
<if test="record.gender != null">
gender = #{record.gender,jdbcType=VARCHAR},
</if>
</set>
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByExample" parameterType="map">
update user_info
set user_id = #{record.userId,jdbcType=VARCHAR},
user_name = #{record.userName,jdbcType=VARCHAR},
introduce = #{record.introduce,jdbcType=VARCHAR},
mobilephone = #{record.mobilephone,jdbcType=VARCHAR},
email = #{record.email,jdbcType=VARCHAR},
birthday = #{record.birthday,jdbcType=DATE},
gender = #{record.gender,jdbcType=VARCHAR}
<if test="_parameter != null">
<include refid="Update_By_Example_Where_Clause" />
</if>
</update>
<update id="updateByPrimaryKeySelective" parameterType="com.gavinbj.confmng.persistence.entity.UserInfo">
update user_info
<set>
<if test="userName != null">
user_name = #{userName,jdbcType=VARCHAR},
</if>
<if test="introduce != null">
introduce = #{introduce,jdbcType=VARCHAR},
</if>
<if test="mobilephone != null">
mobilephone = #{mobilephone,jdbcType=VARCHAR},
</if>
<if test="email != null">
email = #{email,jdbcType=VARCHAR},
</if>
<if test="birthday != null">
birthday = #{birthday,jdbcType=DATE},
</if>
<if test="gender != null">
gender = #{gender,jdbcType=VARCHAR},
</if>
</set>
where user_id = #{userId,jdbcType=VARCHAR}
</update>
<update id="updateByPrimaryKey" parameterType="com.gavinbj.confmng.persistence.entity.UserInfo">
update user_info
set user_name = #{userName,jdbcType=VARCHAR},
introduce = #{introduce,jdbcType=VARCHAR},
mobilephone = #{mobilephone,jdbcType=VARCHAR},
email = #{email,jdbcType=VARCHAR},
birthday = #{birthday,jdbcType=DATE},
gender = #{gender,jdbcType=VARCHAR}
where user_id = #{userId,jdbcType=VARCHAR}
</update>
</mapper>
3. Mapper文件
package com.gavinbj.confmng.persistence.mapper;
import java.io.Serializable;
import java.util.List;
import org.apache.ibatis.annotations.Param;
/**
* DAO公共基类，由MybatisGenerator自动生成请勿修改
* @param <Model> The Model Class 这里是泛型不是Model类
* @param <PK> The Primary Key Class 如果是无主键，则可以用Model来跳过，如果是多主键则是Key类
* @param <E> The Example Class
*/
public interface MyBatisBaseDao<Model, PK extends Serializable, E> {
long countByExample(E example);
int deleteByExample(E example);
int deleteByPrimaryKey(PK id);
int insert(Model record);
int insertSelective(Model record);
List<Model> selectByExample(E example);
Model selectByPrimaryKey(PK id);
int updateByExampleSelective(@Param("record") Model record, @Param("example") E example);
int updateByExample(@Param("record") Model record, @Param("example") E example);
int updateByPrimaryKeySelective(Model record);
int updateByPrimaryKey(Model record);
}
package com.gavinbj.confmng.persistence.mapper;
import com.gavinbj.confmng.persistence.entity.UserInfo;
import com.gavinbj.confmng.persistence.entity.UserInfoExample;
import org.springframework.stereotype.Repository;
/**
* UserInfoMapper继承基类
*/
@Repository
public interface UserInfoMapper extends MyBatisBaseDao<UserInfo, String, UserInfoExample> {
}
6.2.4 使用MyBatis接口
1. ＠MapperScan扫描加载MyBaits的Mapper
package com.gavinbj.confmng;
import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;
/**
* @SpringBootApplication 标注这是SpringBoot项目的主程序类
*/
@MapperScan("com.gavinbj.confmng.persistence.mapper")
@SpringBootApplication
public class ConfManageApplication {
public static void main(String[] args) {
SpringApplication.run(ConfManageApplication.class, args);
}
}
2. UserInfoService & UserInfoServiceImpl
package com.gavinbj.confmng.service;
import java.util.List;
import com.gavinbj.confmng.persistence.entity.UserInfo;
/**
* 用户信息
*
* @author gavinbj
*
*/
public interface UserInfoService {
public UserInfo getUserByPK(String userId);
public List<UserInfo> selectUserInfos(String userName);
}
package com.gavinbj.confmng.service.impl;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import com.gavinbj.confmng.persistence.entity.UserInfo;
import com.gavinbj.confmng.persistence.entity.UserInfoExample;
import com.gavinbj.confmng.persistence.mapper.UserInfoMapper;
import com.gavinbj.confmng.service.UserInfoService;
/**
* 用户信息
*
* @author gavinbj
*
*/
@Service
public class UserInfoServiceImpl implements UserInfoService {
@Autowired
private UserInfoMapper userInfoMapper;
/**
* 根据用户ID进行主键检索
*/
@Override
public UserInfo getUserByPK(String userId) {
return this.userInfoMapper.selectByPrimaryKey(userId);
}
/**
* 根据用户名模糊检索
*
*/
@Override
public List<UserInfo> selectUserInfos(String userName) {
UserInfoExample userExample = new UserInfoExample();
userExample.createCriteria().andUserNameLike(userName);
return this.userInfoMapper.selectByExample(userExample);
}
}
3. Mybatis的Example用法介绍
Example类用来构建一个动态的where子句，根据数据表中的每个非BLOB列可以被包括在where子句中。Example类包含一个内部静态类Criteria以及包含一个用where子句中的条件列表。
创建Criteria对象可以使用Example类中的createCriteria()或者 or() 。使用createCriteria() 创建的Criteria ，它会自动为List属性添加一个Criteria对象，这使得它更容易写一个简单的where子句。
Criteria 内部类的每个属性都包含 andXXX 方法，以及如下的标准的SQL查询方法:
IS NULL - 指相关的列必须为NULL
IS NOT NULL - 指相关的列必须不为NULL
= (equal) - 指相关的列必须等于方法参数中的值
<> (not equal) - 指相关的列必须不等于方法参数中的值
(greater than) - 指相关的列必须大于方法参数中的值
= (greater than or equal) - 指相关的列必须大于等于方法参数中的值
< (less than) - 指相关的列必须小于于方法参数中的值
<= (less than or equal) - 指相关的列必须小于等于方法参数中的值
LIKE - 指相关的列必须 “like” 方法参数中的值. 这个方法不用必须加入 ‘%’, 您必须设置方法参数中的值.
NOT LIKE - 指相关的列必须 “not like” 方法参数中的值. 这个方法不用必须加入 ‘%’, 您必须设置方法参数中的值.
BETWEEN - 指相关的列必须在 “between” 方法参数中的两个值之间.
NOT BETWEEN - 指相关的列必须不在 “not between” 方法参数中的两个值之间.
IN - 指相关的列必须在传入的方法参数的list中.
NOT IN - 指相关的列必须不在传入的方法参数的list中.
4. 创建REST测试接口
package com.gavinbj.confmng.controller;
import java.util.List;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.GetMapping;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.bind.annotation.RestController;
import com.gavinbj.common.bean.BaseResult;
import com.gavinbj.common.bean.ResponseUtils;
import com.gavinbj.confmng.persistence.entity.UserInfo;
import com.gavinbj.confmng.service.UserInfoService;
@RestController
@RequestMapping("/api/user")
public class UserController {
@Autowired
UserInfoService userInfoService;
/**
* 根据用户名进行模糊检索
*
*/
@GetMapping("/users")
public BaseResult<List<UserInfo>> searchUsers(@RequestParam(value = "userName", required = true) String userName) {
List<UserInfo> lstUsers = this.userInfoService.selectUserInfos(userName);
return ResponseUtils.makeOKRsp(lstUsers);
}
/**
* 检索用户信息
*
*/
@GetMapping("/users/{userId}")
public BaseResult<UserInfo> getUserById(@PathVariable("userId") String userId) {
UserInfo userInfo = userInfoService.getUserByPK(userId);
return ResponseUtils.makeOKRsp(userInfo);
}
}
验证测试结果如下：
{
"status": 0,
"code": 1003,
"msg": "处理成功！",
"data": {
"userId": "gavin",
"userName": "盖文",
"introduce": "大学教授",
"mobilephone": "13940981276",
"email": "gavin@qq.com",
"birthday": "2019-10-07T00:00:00.000+0000",
"gender": "男"
}
}