Spring Boot学习笔记（十四）mybatis（一）使用IDEA 整合SpringBoot + mybatis详细流程（有工程源码）

参考SpringBoot整合mybatis快速入门、spring boot +mybatis(通过properties配置) 集成

后来发现一个教程：乐天笔记Mybatis，个人感觉很不错

工程源码：
链接：https

一、准备数据库

安装好mysql数据库后，打开workbench

CREATE TABLE `tb_user` (
  `id` int(11) NOT NULL AUTO_INCREMENT COMMENT 'ID',
  `username` varchar(50) NOT NULL COMMENT '用户名',
  `age` int(11) NOT NULL COMMENT '年龄',
  `ctm` datetime NOT NULL COMMENT '创建时间',
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=8 DEFAULT CHARSET=utf8;

-- ----------------------------
-- Records of tb_user
-- ----------------------------
INSERT INTO `tb_user` VALUES ('1', '张三', '18', '2019-01-24 09:07:41');
INSERT INTO `tb_user` VALUES ('2', '李四', '20', '2019-01-24 09:07:41');
INSERT INTO `tb_user` VALUES ('3', '王五', '19', '2019-01-24 09:07:41');

二、新建SpringBoot工程

等待Spring boot 工程的新建以及依赖的自动下载，打开pom，确认一下是否有一下依赖（版本可不同）

        <!--web核心依赖-->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-web</artifactId>
        </dependency>

        <!--mysql数据库驱动-->
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>

        <!--mybatis-->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.1.0</version>
        </dependency>

三、创建文件

1、准备工作

我们最终的文件目录如下所示

首先，让我们来添加模板文件，方便以后快速生成mybatis配置文件(图片来源)

• 我们依照以上步骤，创建mybatis-config模板，以下为填入的代码

<?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>
    <settings>
        <setting name="callSettersOnNulls" value="true"/>
        
        <setting name="cacheEnabled" value="true"/>
        
        <setting name="lazyLoadingEnabled" value="true"/>
        
        <setting name="aggressiveLazyLoading" value="true"/>
        
        <setting name="multipleResultSetsEnabled" value="true"/>
        
        <setting name="useColumnLabel" value="true"/>
        
        <setting name="useGeneratedKeys" value="false"/>
        
        <setting name="autoMappingBehavior" value="PARTIAL"/>
        
        <setting name="defaultExecutorType" value="SIMPLE"/>
        
        <setting name="mapUnderscoreToCamelCase" value="true"/>
        
        <setting name="localCacheScope" value="SESSION"/>
        
        <setting name="jdbcTypeForNull" value="NULL"/>
        
    </settings>
 
    <typeAliases>
        <typeAlias alias="Integer" type="java.lang.Integer" />
        <typeAlias alias="Long" type="java.lang.Long" />
        <typeAlias alias="HashMap" type="java.util.HashMap" />
        <typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />
        <typeAlias alias="ArrayList" type="java.util.ArrayList" />
        <typeAlias alias="LinkedList" type="java.util.LinkedList" />
    </typeAliases>
</configuration>

• 创建mabatis-mapper模板，以下为填入的代码

<?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="">
</mapper>

2、开始实践

① 修改application.properties

# 服务器端口，如果不配置默认是8080端口
server.port=8096 

# 数据库设置
spring.datasource.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.url=jdbc:mysql://127.0.0.1:3306/jdbclearn?serverTimezone=UTC&useUnicode=true&characterEncoding=utf8
spring.datasource.username=root
spring.datasource.password=123456

#配置.xml文件路径
# 若没有在最前面加上/，则路径均默认为resource下，若想要指定工程文件中的文件，也可以写为：/com/example/demo/你的文件层级/*.xml
mybatis.config-locations=classpath:mybatis/mybatis-config.xml
mybatis.mapper-locations=classpath:mybatis/mapper/*.xml

② 新建并编写UserEntity.class文件

import org.apache.ibatis.annotations.Mapper;
import java.io.Serializable;
import java.util.Date;
@Mapper
public class UserEntity implements Serializable {
    private static final long serialVersionUID = 1L;

    private int id;
    private String username;
    private int age;
    private Date ctm;

    public int getId() {
        return id;
    }

    public String getUsername() {
        return username;
    }

    public int getAge() {
        return age;
    }

    public Date getCtm() {
        return ctm;
    }

    public void setId(int id) {
        this.id = id;
    }

    public void setUsername(String username) {
        this.username = username;
    }

    public void setAge(int age) {
        this.age = age;
    }

    public void setCtm(Date ctm) {
        this.ctm = ctm;
    }
}

③ 新建并编写的UserMapper.class文件

import com.example.demo.entity.UserEntity;
import org.apache.ibatis.annotations.Mapper;
import java.util.List;

@Mapper
public interface UserMapper {
    List<UserEntity> findAll();
}

• 新建并编写我们的mybatis下的mybatis-config.xml
  
  如果之前有根据教程创建模板的话，按照下图流程，可直接创建
  
  若没有创建模板则创建一个xml文件后，填写代码

<?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>
    <settings>
        <setting name="callSettersOnNulls" value="true"/>

        <setting name="cacheEnabled" value="true"/>

        <setting name="lazyLoadingEnabled" value="true"/>

        <setting name="aggressiveLazyLoading" value="true"/>

        <setting name="multipleResultSetsEnabled" value="true"/>

        <setting name="useColumnLabel" value="true"/>

        <setting name="useGeneratedKeys" value="false"/>

        <setting name="autoMappingBehavior" value="PARTIAL"/>

        <setting name="defaultExecutorType" value="SIMPLE"/>

        <setting name="mapUnderscoreToCamelCase" value="true"/>

        <setting name="localCacheScope" value="SESSION"/>

        <setting name="jdbcTypeForNull" value="NULL"/>

    </settings>

    <typeAliases>
        <typeAlias alias="Integer" type="java.lang.Integer" />
        <typeAlias alias="Long" type="java.lang.Long" />
        <typeAlias alias="HashMap" type="java.util.HashMap" />
        <typeAlias alias="LinkedHashMap" type="java.util.LinkedHashMap" />
        <typeAlias alias="ArrayList" type="java.util.ArrayList" />
        <typeAlias alias="LinkedList" type="java.util.LinkedList" />
    </typeAliases>
</configuration>

④ 新建并编写我们的mybatis/mapper下的UserMapper.xml（也可以通过模板快速创建框架）

<?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.example.demo.mapper.UserMapper">
    <select id="findAll" resultType="com.example.demo.entity.UserEntity">
        SELECT * FROM tb_user
    </select>
</mapper>

⑤ 创建并编写我们的Service.class

import java.util.List;

public interface UserService {
    List<UserEntity> findAll();
}

⑥ 创建并编写我们的ServiceImpl.class

import org.springframework.stereotype.Service;
import javax.annotation.Resource;
import java.util.List;

@Service
public class UserServiceImpl implements UserService {
//    此处若@Autowire可能会出现红色错误Could not autowire. No beans of 'xxxMapper' type found.但仍可执行
//    将byType进行自动填充的AutoWire换成 byName注入的@Resource，则不会有此问题
//    如果一定要使用Autowire，则需要在SpringBoot启动类（此工程中为DemoApplication）添加@MapperScaner
    @Resource
    private UserMapper userMapper;

    @Override
    public List<UserEntity> findAll() {
        return userMapper.findAll();
    }
}

⑦ 创建并编写我们的UserController.class

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RestController;

import java.util.List;

@RestController
@RequestMapping("/user")
public class UserController {

    @Autowired
    private UserServiceImpl userServiceImpl;

    @RequestMapping("/findAll")
    public List<UserEntity> findAll(){
        return userServiceImpl.findAll();
    }

}

四、测试

我们启动项目后
在浏览器输入地址localhost:8096/user/findAll（或者用postman进行测试）查询成功