SpringBoot 集成Mybatis

1,必要的依赖：

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version>
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <!-- 指定一下jdk的版本 ，这里我们使用jdk 1.8 ,默认是1.6 -->
        <java.version>1.8</java.version>
    </properties>

    <!-- spring-boot-starter-web: MVC,AOP的依赖包.... -->
    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>
        
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter</artifactId>
        </dependency>
        <!-- 测试 -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>
        <!-- mysql 依赖 -->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

  </dependencies>

2, mysql 数据库 testdb 下有张user 表：

3，表对应的实体类:

import lombok.Data;
@Data //相当于@Setter @Getter
public class User {
    private int id;
    private String username;
    private String sex;
    private Date birthday;
    private String address;
}

4,mapper 接口(dao)

  

package com.baiyue.mappers;

import java.util.List;
import java.util.Map;
import org.apache.ibatis.annotations.Param;
import org.apache.ibatis.annotations.Select;
import com.baiyue.entity.User;

public interface UserMapper {

    void insertUser(User user);

    User selectUserById(int id);

    List<User> selectAllUser();

    // 模糊查询的
    List<User> selectUserNameLike(String username);

    List<User> selectByName(String username);

    void deleteUserById(int id);

    // 多参数 传递方式1
    // public void updateUserById(@Param("id")int id,@Param("username")String
    // username);

    // 多参数 传递方式2
    void updateUserById(Map<String, Object> map);

    // 使用注解 字符串替换 不用写根据id查 根据username查 根据address 查
    @Select("select * from user where ${column} = #{value}")
    List<User> findByColumn(@Param("column") String column, @Param("value") String value);

    // resultMap 结果映射 只想输出部分的属性
    User selectUserByIdMap(int id);

    // 动态sql SELECT * FROM testdb.user where username='Linda' and sex='male';
    List<User> selectUsers(Map<String, String> map);

    void update(String username, String sex, int age);

}

5，mapper.xml

<?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.baiyue.mappers.UserMapper">

    <!-- 根据 id 查询 user 表中的数据 id:唯一标识符，此文件中的id值不能重复 resultType:返回值类型，一条数据库记录也就对应实体类的一个对象 
        parameterType:参数类型，也就是查询条件的类型 -->
    <select id="selectUserById" resultType="User" parameterType="int">
        <!-- 这里和普通的sql 查询语句差不多，对于只有一个参数，后面的 #{id}表示占位符，里面不一定要写id,写啥都可以，但是不要空着，如果有多个参数则必须写pojo类里面的属性 -->
        select * from user where id = #{id}
    </select>

    <insert id="insertUser" parameterType="com.baiyue.entity.User">
        insert into
        user(id,username,sex,birthday,address)
        value(#{id},#{username},#{sex},#{birthday},#{address})
    </insert>

    <select id="selectAllUser" resultType="com.baiyue.entity.User">
        select * from user
    </select>

    <select id="selectUserNameLike" parameterType="java.lang.String"
        resultType="com.baiyue.entity.User">
        select * from user where username like '%${value}%'
    </select>

    <select id="selectByName" parameterType="java.lang.String"
        resultType="com.baiyue.entity.User">
        select * from user where username = #{username}
    </select>

    <delete id="deleteUserById" parameterType="int">
        delete from user where
        id=#{id}
    </delete>

    <update id="updateUserById" parameterType="java.util.Map">
        update user set
        username=#{username} where id=#{id}
    </update>

    <!-- resultMap -->

    <resultMap id="userResultMap" type="com.baiyue.entity.User">
        <id property="id" column="id" />
        <result property="username" column="username" />
        <result property="address" column="address" />
    </resultMap>

    <select id="selectUserByIdMap" resultMap="userResultMap"
        parameterType="int">
        <!-- 数据库address 对应address_city -->
        select id,username,address from user where id =#{id}
    </select>

    <select id="selectUsers"  resultType="com.baiyue.entity.User" parameterType="java.util.Map" >
        select * from user where username =#{username}
        <if test="sex != female">
            AND sex =#{sex}
        </if>
    </select>

</mapper>

6,配置文件链接mapper 和 mapper.xml

spring:
  datasource:
    url: jdbc:mysql://127.0.0.1:3306/testdb
    username: root
    password: 123456
    driver-class-name: com.mysql.jdbc.Driver
    
 # mybatis
mybatis:
  mapper-locations: classpath:com/baiyue/mapping/*Mapper.xml
  type-aliases-package: com.baiyue.entity

7, service 层

package com.baiyue.service;

import java.util.List;
import java.util.Map;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.baiyue.entity.User;
import com.baiyue.mappers.UserMapper;
import com.github.pagehelper.PageInfo;

@Service
public class UserService {

    @Autowired
    private UserMapper userMapper;

    public void insertUser(User user) {
        userMapper.insertUser(user);
    };

    public User selectUserById(int id) {
        User user = userMapper.selectUserById(id);
        return user;
    };

    public List<User> selectAllUser() {
        List<User> list = userMapper.selectAllUser();
        return list;
    };

    // 模糊查询的
    public List<User> selectUserNameLike(String username) {
        List<User> list = userMapper.selectUserNameLike(username);
        return list;
    };

    public List<User> selectByName(String username) {
        List<User> list = userMapper.selectByName(username);
        return list;
    };

    public void deleteUserById(int id) {
        userMapper.deleteUserById(id);
    };

    // 多参数 传递方式1
    // public void updateUserById(@Param("id")int id,@Param("username")String
    // username);

    // 多参数 传递方式2
    public void updateUserById(Map<String, Object> map) {
        userMapper.updateUserById(map);
    };

    // 使用注解 字符串替换 不用写根据id查 根据username查 根据address 查
    List<User> findByColumn(String column, String value) {
        List<User> list = userMapper.findByColumn(column, value);
        return list;
    };

    // resultMap 结果映射 只想输出部分的属性
    public User selectUserByIdMap(int id) {
        User user = userMapper.selectUserByIdMap(id);
        return user;
    };

    // 动态sql SELECT * FROM testdb.user where username='Linda' and sex='male';
    public List<User> selectUsers(Map<String, String> map) {
        List<User> list = userMapper.selectUsers(map);
        return list;
    };

    public void update(String username, String sex, int age) {
        userMapper.update(username, sex, age);
    };
    

}

8,controller 层：

@RestController
public class Mybatis {
    
    @Autowired
    private UserService userService;
    
    @RequestMapping("/insertUser")
    public String insertUser(){
        User user = new User();
        user.setUsername("chris");
        user.setSex("male");
        userService.insertUser(user);
        return "success";
    }

}

7，启动类,要加上mapper 的扫包：

@SpringBootApplication
@ComponentScan("com.baiyue.*") //因为有一些bean 不在当前包或者子包下面，所以@SpringBootApplication 会有些bean 扫不到
@MapperScan("com.baiyue.mappers")
public class App {
    public static void main(String[] args) {
        SpringApplication.run(App.class, args);
    }
}

在集成mybatis的基础上，使用分页插件：

        <!-- springboot 整合 pagehelper -->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.5</version>
        </dependency>

service 层添加方法：

    //使用pageHelper 分页插件 page是页码 size 是个数
    public PageInfo<User> selectUserByPagehelper(int page,int size){
        PageHelper.startPage(page, size);
        //底层会将sql 分装，直接搜索条件中的页数，以及数量
        List<User> list = userMapper.selectAllUser(); //前后都是一样的代码可以用AOP进行封装
        PageInfo<User> pageInfo = new PageInfo<>(list);
        return pageInfo;
    }
    

controller 层：

    @RequestMapping("/selectUserByPagehelper")
    public PageInfo<User> selectUserByPagehelper(int page,int size){
        User user = new User();
        PageInfo<User> pageInfo = userService.selectUserByPagehelper(page, size);
        return pageInfo;
    }