最近一直公司代码框架由hibernate切换到mybatis，springboot以及cloud如火如荼，所以写了这篇文章用于记录。

项目工具：idea + maven + mysql

一、创建数据库和数据表

1、创建数据库 test_mybatis

CREATE DATABASE test_mybatis;

2、创建表 user

CREATE TABLE `user` (
    `user_id` INT(11) NOT NULL COMMENT '主键',
    `user_name` VARCHAR(64) NOT NULL COMMENT '姓名',
    `address` VARCHAR(256) NULL DEFAULT NULL COMMENT '地址',
    PRIMARY KEY (`user_id`)
)
COLLATE='utf8_general_ci'
ENGINE=InnoDB;

3、插入数据

insert into user(user_id,user_name,address) values(1,"小明","北京市朝阳区望京");
insert into user(user_id,user_name,address) values(2,"小红","北京市东城区东直门");
insert into user(user_id,user_name,address) values(3,"小绿","北京市西城区车公庄");

二、项目代码

1、创建一个springboot项目。修改pom文件，完整文件如下：

<?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>

<groupId>com.xinput</groupId>
<artifactId>springbootMybatisXml</artifactId>
<version>1.0-SNAPSHOT</version>

<!-- Spring Boot 启动父依赖 -->
<parent>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-parent</artifactId>
    <version>1.5.1.RELEASE</version>
</parent>

<properties>
    <mysql.version>5.1.39</mysql.version>
</properties>

<dependencies>
    <!-- Spring Boot Web 依赖 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-web</artifactId>
    </dependency>
    <!-- Spring Boot Test 依赖 -->
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
    </dependency>

    <!-- Spring Boot Mybatis 依赖 -->
    <dependency>
        <groupId>org.mybatis.spring.boot</groupId>
        <artifactId>mybatis-spring-boot-starter</artifactId>
        <version>1.2.0</version>
    </dependency>

    <!-- MySQL 连接驱动依赖 -->
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <version>${mysql.version}</version>
    </dependency>

    <!-- Junit -->
    <dependency>
        <groupId>junit</groupId>
        <artifactId>junit</artifactId>
        <version>4.12</version>
    </dependency>
</dependencies>

<build>
    <plugins>
        <plugin>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-maven-plugin</artifactId>
        </plugin>
        <plugin>
            <groupId>org.apache.maven.plugins</groupId>
            <artifactId>maven-surefire-plugin</artifactId>
            <configuration>
                <skip>true</skip>
            </configuration>
        </plugin>
    </plugins>
</build>
</project>

2、创建实体类 User

package com.xinput.entity;

import java.io.Serializable;

public class User implements Serializable {
private static final long serialVersionUID = 8296061679272038443L;

private Long userId;
private String userName;
private String address;

// get set方法

@Override
public String toString() {
    return "User{" +
            "userId=" + userId +
            ", userName='" + userName + '\'' +
            ", address='" + address + '\'' +
            '}';
}

}

3、创建dao接口文件

package com.xinput.dao;

import com.xinput.entity.User;
import org.apache.ibatis.annotations.Mapper;

@Mapper
public interface UserMapper {
int insertUser(User userEntity);

User selectByPrimaryKey(Long userId);

User selectByName(String userName);
}

4、创建dao和entity对应的UserMapper.xml配置文件

<?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.xinput.dao.UserMapper">
    <resultMap id="BaseResultMap" type="com.xinput.entity.User">
    <id column="user_id" property="userId" jdbcType="INTEGER"/>
    <result column="user_name" property="userName" jdbcType="VARCHAR"/>
    <result column="address" property="address" jdbcType="VARCHAR"/>
</resultMap>
<sql id="Base_Column_List">
    user_id,user_name,address
</sql>

<!--================测试用：生成user===================-->
<insert id="insertUser" parameterType="com.xinput.entity.User">
    insert into user
    <trim prefix="(" suffix=")" suffixOverrides=",">
        <if test="userId != null">user_id,</if>
        <if test="userName != null">user_name,</if>
        <if test="address != null">address,</if>
    </trim>
    <trim prefix="values (" suffix=")" suffixOverrides=",">
        <if test="userId != null">#{userId,jdbcType=INTEGER},</if>
        <if test="userName != null">#{userName,jdbcType=VARCHAR},</if>
        <if test="address != null">#{address,jdbcType=VARCHAR},</if>
    </trim>
</insert>

<!--================根据主键查商户===================-->
<select id="selectByPrimaryKey" resultMap="BaseResultMap" parameterType="java.lang.Long">
    select
    <include refid="Base_Column_List"/>
    from user
    where user_id = #{userId,jdbcType=CHAR}
</select>

<!--================根据name查商户===================-->
<select id="selectByName" resultMap="BaseResultMap" parameterType="java.lang.String">
    select
    <include refid="Base_Column_List"/>
    from user
    where user_name = #{userName,jdbcType=CHAR}
</select>
</mapper>

5、创建service类，spring中，其实可以不用写接口，可以直接写service类

//服务类
package com.xinput.service;

import com.xinput.dao.UserMapper;
import com.xinput.entity.User;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

@Service
public class UserService {

   @Autowired
    UserMapper userMapper;

    public User getUserById(Long userId) {
        return userMapper.selectByPrimaryKey(userId);
    }
}

6、修改appilcation.properties文件配置

#嵌入tomcat默认端口
server.port=8081

#mysql属性
spring.datasource.url=jdbc:mysql://192.168.99.100:3306/test_mybatis?        useUnicode=true&characterEncoding=utf-8&autoReconnect=true&failOverReadOnly=false
spring.datasource.username=root
spring.datasource.password=123
spring.datasource.driver-class-name=com.mysql.jdbc.Driver
# 初始化大小，最小，最大
spring.datasource.initialSize=5
spring.datasource.minIdle=5
spring.datasource.maxActive=20
# 配置获取连接等待超时的时间
spring.datasource.maxWait=60000
# 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒
spring.datasource.timeBetweenEvictionRunsMillis=60000
# 配置一个连接在池中最小生存的时间，单位是毫秒
spring.datasource.minEvictableIdleTimeMillis=300000
spring.datasource.validationQuery=SELECT 1 FROM DUAL
spring.datasource.testWhileIdle=true
spring.datasource.testOnBorrow=false
spring.datasource.testOnReturn=false

#mybatis
# 为实体对象所在的包，跟数据库表一一对应
mybatis.typeAliasesPackage=com.xinput.entity
# typeAliasesPackage: com.xinput.**.mapper
# mapper文件的位置
mybatis.mapper-locations=classpath:mapper/*Mapper.xml

注释：
mybatis 其他配置相关详解如下：
mybatis.config = mybatis 配置文件名称
mybatis.mapperLocations = mapper xml 文件地址
mybatis.typeAliasesPackage = 实体类包路径
mybatis.typeHandlersPackage = type handlers 处理器包路径
mybatis.check-config-location = 检查 mybatis 配置是否存在，一般命名为 mybatis-config.xml
mybatis.executorType = 执行模式。默认是 SIMPLE3.在 Application 应用启动类添加注解 MapperScan

7、controller类代码

package com.xinput.controller;

import com.xinput.entity.User;
import com.xinput.service.UserService;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.*;

@RestController
public class UserController {

    @Autowired
    UserService userService;

    @RequestMapping(value="/user/{id}",method= RequestMethod.GET)
    public User findUser(@PathVariable("id")Long id){
        User user = userService.getUserById(id);
        return user;
    }
}

8、修改Application.java启动类代码

package com.xinput;

import org.mybatis.spring.annotation.MapperScan;
import org.springframework.boot.SpringApplication;
import org.springframework.boot.autoconfigure.SpringBootApplication;

@SpringBootApplication
@MapperScan(basePackages="com.xinput.dao")
public class Application {
    public static void main(String[] args){
        SpringApplication.run(Application.class,args);
    }
}

三、启动 Application

访问 http://localhost:8081/user/1。

如果大家觉得还有什么问题，可以给我留言，我看到会回复的。