springboot-整合mybatis

1.创建springboot项目，注意这里的版本选择2.0.0，之前因为用的别的版本在配置Mybatis的时候老是出错（使用jpa也是一样）

添加这两个依赖：

    <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>

<?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.xidian.house</groupId>
    <artifactId>house</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <packaging>jar</packaging>

    <name>hosue</name>
    <description>房产销售平台</description>

    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.0.0.RELEASE</version><!-- 当要使用mybatis 或者jpa的时候一定要使用2.0.0.0的版本 -->
        <relativePath/> <!-- lookup parent from repository -->
    </parent>

    <properties>
        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
        <java.version>1.8</java.version>
    </properties>

    <dependencies>
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-freemarker</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>
        
        <!-- https://mvnrepository.com/artifact/org.mybatis.spring.boot/mybatis-spring-boot-starter -->
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>1.1.1</version>
        </dependency>

        
        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
        </dependency>
        
    </dependencies>

    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>


</project>

2. 在application.yml配置数据库和Mybatis文件

spring:
 datasource:
    driver-class-name: com.mysql.jdbc.Driver
    url: jdbc:mysql://127.0.0.1:3306/house
    username: root
    password: root
mybatis:
  config-location: classpath:/mybatis/mybatis-config.xml

3.配置mybatis-config.xml

<?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>
    <!--配置關閉緩存  -->
    <setting name="cacheEnabled" value="false"/>
    <setting name="mapUnderscoreToCamelCase" value="true"/><!-- 將表的下劃線形式映射成駝峰形式 -->
    <setting name="useGeneratedKeys" value="true"/>
    <setting name="defaultExecutorType" value="REUSE"/>
    <!-- 事務超時時間 -->
    <setting name="defaultStatementTimeout" value="600"/>
    </settings>

    <typeAliases><!-- 定義對象的別名 ,在mapping.xml文件中非常有用-->
     <typeAlias type="com.xidian.house.common.model.User" alias="user"/>
    
    </typeAliases>
    
    <mappers><!-- 定義sql文件的邏輯 -->
    <mapper resource="mapper/user.xml"/>
    
    </mappers>

</configuration>

3.定义user类

public class User {

private Long id;

public Long getId() {
return id;
}

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

}

4.新建接口UserMapper

@Mapper
public interface UserMapper {
    
    public List<User> selectUser();

}

5.user.xml是和UserMapper对应的，一个接口方法对应一条sql语句

<mapper namespace="com.xidian.house.mapper.UserMapper">
    <select id="selectUser" resultType="user">
    select id from user
    </select>

</mapper>

6.创建service类

@Service
public class UserServie {
    
    @Autowired
    private UserMapper userMapper;
    
    public List<User> getUsers(){
        return userMapper.selectUser();
    }

}

7.创建controll类

@RestController
public class UserController {
    
    @Autowired
    private UserServie userService;
    
    @RequestMapping("/user")
    public List<User> getUsers(){
        return userService.getUsers();
    }

}

8.在启动类中配置@MapperScan("com.xidian.house.mapper")，在启动的时候就能扫描指定包中的mapper文件，将其配置成Spring的bean

@SpringBootApplication
@MapperScan("com.xidian.house.mapper")
public class HosueApplication {

    public static void main(String[] args) {
        SpringApplication.run(HosueApplication.class, args);
    }
}

浏览器中输入地址：http://127.0.0.1:8080/user

显示输出：[{"id":15},{"id":29},{"id":14},{"id":8},{"id":9},{"id":10},{"id":11},{"id":12},{"id":13},{"id":27},{"id":7}]