Spring boot 2.1.1 整合 mybatis （超详细）

在idea 14以上版本中就已经支持创建Spring Boot
本项目使用的环境：

开发工具：

• intellij idea 2018.2
• jdk1.8
• maven3.3.9

额外功能：

• PageHelper 分页插件
• mybatis generator 自动生成代码插件

1.点击菜单栏 File -> New ->Project 创建项目

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• 看一下项目的初始结构：
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  pom文件：

<?xml version="1.0" encoding="UTF-8"?>
<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.1.1.RELEASE</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.mhg</groupId>
    <artifactId>mhg</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>
    <name>mhg</name>
    <description>Demo project for Spring Boot</description>

    <properties>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-jdbc</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.3.0</version>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-thymeleaf</artifactId>
        </dependency>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <version>5.1.35</version>
        </dependency>
        <!--alibaba的druid数据库连接池-->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
            <version>1.1.9</version>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-core</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.core</groupId>
            <artifactId>jackson-databind</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.datatype</groupId>
            <artifactId>jackson-datatype-joda</artifactId>
        </dependency>
        <dependency>
            <groupId>com.fasterxml.jackson.module</groupId>
            <artifactId>jackson-module-parameter-names</artifactId>
        </dependency>
        <!-- 分页插件 ：该版本只支持spring boot2.0以上版本-->
        <dependency>
            <groupId>com.github.pagehelper</groupId>
            <artifactId>pagehelper-spring-boot-starter</artifactId>
            <version>1.2.3</version>
        </dependency>
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
            <!-- mybatis generator 自动生成代码插件 -->
            <plugin>
                <groupId>org.mybatis.generator</groupId>
                <artifactId>mybatis-generator-maven-plugin</artifactId>
                <version>1.3.2</version>
                <configuration>
                    <configurationFile>${basedir}/src/main/resources/generator/generatorConfig.xml</configurationFile>
                    <overwrite>true</overwrite>
                    <verbose>true</verbose>
                </configuration>
            </plugin>
        </plugins>
    </build>

</project>

• 项目不使用application.properties文件 而使用更加简洁的application.yml文件：
  将原有的resource文件夹下的application.properties文件删除，创建一个新的application.yml配置文件，
  文件的内容如下:

server:
  port: 8080

spring:
  datasource:
    name: test
    url: jdbc:mysql://112.74.133.224:3306/mytest
    username: root
    password: root
    # 使用druid数据源
    type: com.alibaba.druid.pool.DruidDataSource
    driver-class-name: com.mysql.jdbc.Driver
    filters: stat
    maxActive: 20
    initialSize: 1
    maxWait: 60000
    minIdle: 1
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    validationQuery: select 'x'
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
    maxOpenPreparedStatements: 20
mybatis:
  mapper-locations: classpath:mapping/*.xml
  type-aliases-package: com.yxzjfk.model
#pagehelper分页插件
pagehelper:
  helperDialect: mysql
  reasonable: true
  supportMethodsArguments: true
  params: count=countSql

• 下一步就是创建数据库：

CREATE DATABASE mytest;
 
CREATE TABLE t_user(
  user_id INT NOT NULL PRIMARY KEY AUTO_INCREMENT,
  user_name VARCHAR(255) NOT NULL ,
) ENGINE=INNODB AUTO_INCREMENT=1000 DEFAULT CHARSET=utf8;

• 使用mybatis generator 自动生成代码,在resource下新建一个generator目录、随后建立generatorConfig.xml文件
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• generatorConfig.xml内容如下:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE generatorConfiguration
        PUBLIC "-//mybatis.org//DTD MyBatis Generator Configuration 1.0//EN"
        "http://mybatis.org/dtd/mybatis-generator-config_1_0.dtd">
<generatorConfiguration>
    <!-- 数据库驱动:选择你的本地硬盘上面的数据库驱动包-->
    <classPathEntry  location="D:\myFile\software\apache-maven-3.1.1\localhost_repository\mysql\mysql-connector-java\5.1.6\mysql-connector-java-5.1.6.jar"/>
    <context id="DB2Tables"  targetRuntime="MyBatis3">
        <commentGenerator>
            <property name="suppressDate" value="true"/>
            <!-- 是否去除自动生成的注释 true：是 ： false:否 -->
            <property name="suppressAllComments" value="true"/>
        </commentGenerator>
        <!--数据库链接URL，用户名、密码 -->
        <jdbcConnection driverClass="com.mysql.jdbc.Driver" connectionURL="jdbc:mysql://112.74.133.224:3306/mytest?characterEncoding=utf-8" userId="root" password="root">
        </jdbcConnection>
        <javaTypeResolver>
            <property name="forceBigDecimals" value="false"/>
        </javaTypeResolver>
        <!-- 生成模型的包名和位置-->
        <javaModelGenerator targetPackage="main.java.com.mhg.model" targetProject="src">
            <property name="enableSubPackages" value="true"/>
            <property name="trimStrings" value="true"/>
        </javaModelGenerator>
        <!-- 生成映射文件的包名和位置-->
        <sqlMapGenerator targetPackage="main.resources.mapping" targetProject="src">
            <property name="enableSubPackages" value="true"/>
        </sqlMapGenerator>
        <!-- 生成DAO的包名和位置-->
        <javaClientGenerator type="XMLMAPPER" targetPackage="main.java.com.mhg.mapper" targetProject="src">
            <property name="enableSubPackages" value="true"/>
        </javaClientGenerator>
        <!-- 要生成的表 tableName是数据库中的表名或视图名 domainObjectName是实体类名-->
        <table tableName="t_user" domainObjectName="User" enableCountByExample="false" enableUpdateByExample="false" enableDeleteByExample="false" enableSelectByExample="false" selectByExampleQueryId="false"></table>
    </context>
</generatorConfiguration>

• 下面将演示如何在intellij idea下运行generator自动生成代码：
  点击run-Edit Configurations
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参数：mybatis-generator:generate -e

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• 运行
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• 最后生成的文件以及结构：
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注意：由于生成的类中的路径写了全路径，需要把前面多余的"main.java."删除，

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• 生成的UserMapper.java

package com.yxzjfk.mapper;

import com.yxzjfk.model.User;

import java.util.List;

public interface UserMapper {
    int deleteByPrimaryKey(Integer userId);

    int insert(User record);

    int insertSelective(User record);

    User selectByPrimaryKey(Integer userId);

    int updateByPrimaryKeySelective(User record);

    int updateByPrimaryKey(User record);

    List<User> selectAllUser();
}

• 生成的User.java

package com.mhg.model;

public class User {
    private Integer userId;

    private String userName;

    public Integer getUserId() {
        return userId;
    }

    public void setUserId(Integer userId) {
        this.userId = userId;
    }

    public String getUserName() {
        return userName;
    }

    public void setUserName(String userName) {
        this.userName = userName == null ? null : userName.trim();
    }
}

• 生成的UserMapper.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.mhg.mapper.UserMapper" >
  <resultMap id="BaseResultMap" type="com.mhg.model.User" >
    <id column="user_id" property="userId" jdbcType="INTEGER" />
    <result column="user_name" property="userName" jdbcType="VARCHAR" />
  </resultMap>
  <sql id="Base_Column_List" >
    user_id, user_name
  </sql>
  <select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Integer" >
    select 
    <include refid="Base_Column_List" />
    from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </select>
  <delete id="deleteByPrimaryKey" parameterType="java.lang.Integer" >
    delete from t_user
    where user_id = #{userId,jdbcType=INTEGER}
  </delete>
  <insert id="insert" parameterType="com.mhg.model.User" >
    insert into t_user (user_id, user_name)
    values (#{userId,jdbcType=INTEGER}, #{userName,jdbcType=VARCHAR})
  </insert>
  <insert id="insertSelective" parameterType="com.mhg.model.User" >
    insert into t_user
    <trim prefix="(" suffix=")" suffixOverrides="," >
      <if test="userId != null" >
        user_id,
      </if>
      <if test="userName != null" >
        user_name,
      </if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides="," >
      <if test="userId != null" >
        #{userId,jdbcType=INTEGER},
      </if>
      <if test="userName != null" >
        #{userName,jdbcType=VARCHAR},
      </if>
    </trim>
  </insert>
  <update id="updateByPrimaryKeySelective" parameterType="com.mhg.model.User" >
    update t_user
    <set >
      <if test="userName != null" >
        user_name = #{userName,jdbcType=VARCHAR},
      </if>
    </set>
    where user_id = #{userId,jdbcType=INTEGER}
  </update>
  <update id="updateByPrimaryKey" parameterType="com.mhg.model.User" >
    update t_user
    set user_name = #{userName,jdbcType=VARCHAR}
    where user_id = #{userId,jdbcType=INTEGER}
  </update>

  <select id="selectAllUser" resultMap="BaseResultMap">
    select
    <include refid="Base_Column_List" />
    from t_user
  </select>
</mapper>

• .打开springboot的启动类。需要增加@MapperScan注解，（为了让spring boot扫描mapper文件）
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• 编写service 、serviceImpl、controller类 来进行测试：

UserService :

package com.mhg.service;

import com.mhg.model.User;

import java.util.List;

public interface UserService {
    /**
     * 添加User
     * @param user
     * @return
     */
    int addUser(User user);

    /**
     * 查询User集合
     * @param pageNum
     * @param pageSize
     * @return
     */
    List<User> findUserAll(int pageNum, int pageSize);
}

UserServiceImpl:

package com.mhg.service.impl;

import com.github.pagehelper.PageHelper;
import com.mhg.mapper.UserMapper;
import com.mhg.model.User;
import com.mhg.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import java.util.List;

@Service
public class UserServiceImpl implements UserService {
    @Autowired
    private UserMapper userMapper;//由于intellij idea检测级别，导致这里会报错，但是不影响运行

    @Override
    public int addUser(User user) {
        return userMapper.insertSelective(user);
    }

    /*
     * 这个方法中用到了配置依赖的分页插件pagehelper
     * 很简单，只需要在service层传入参数，然后将参数传递给一个插件的一个静态方法即可；
     * pageNum 开始页数
     * pageSize 每页显示的数据条数
     * */
    @Override
    public List<User> findUserAll(int pageNum, int pageSize) {
        //将参数传给这个方法就可以实现物理分页
        PageHelper.startPage(pageNum, pageSize);
        return userMapper.selectAllUser();
    }
}

UserController:

package com.mhg.controller;

import com.mhg.model.User;
import com.mhg.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;
import org.springframework.web.bind.annotation.PathVariable;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.ResponseBody;

@Controller
@RequestMapping(value = "/user")
public class UserController {
    @Autowired
    private UserService userService;

    @ResponseBody
    @RequestMapping(value = "/addUser")
    public int addUser(User user){
        return userService.addUser(user);
    }

    @ResponseBody
    @RequestMapping(value = "/all/{pageNum}/{pageSize}",produces = {"application/json;charset=UTF-8"})
    public Object findAllUser(@PathVariable("pageNum") int pageNum, @PathVariable("pageSize") int pageSize){
        System.out.print(pageNum);
        return userService.findUserAll(pageNum,pageSize);
    }

    @ResponseBody
    @RequestMapping(value = "/hello")
    public String hello(){
        return "周杰伦";
    }

}

让我们测试一下添加User：

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测试分页：

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至此，整个框架已搭建完成。