springboot2.5.5配置mybatis

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【README】

1.本文记录了 springboot2.5.5 配置 mybatis的步骤；

2.配置mybatis 分为注解和配置两种方式；

3.引入mybatis，包括了

  1. 创建springbt项目；
  2. druid数据源配置；
  3. 数据库表与javabean；
  4. mybatis配置与sql映射；
  5. 用户请求controller处理；

【1】springboot使用@注解引入mybatis

【1.1】创建springboot项目

步骤1， 新建springboot项目；

步骤2，选择依赖，包括springweb，mysql驱动，mybatis；（当然也可以手动录入 maven 依赖）

因为  mybatis-spring-boot-starter 引入了 jdbc starter，所需这里无需引入；

pom.xml 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 https://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>2.5.5</version>
        <relativePath/> <!-- lookup parent from repository -->
    </parent>
    <groupId>com.cmc</groupId>
    <artifactId>springbt-06-data-mybatis2</artifactId>
    <version>0.0.1-SNAPSHOT</version>
    <name>springbt-06-data-mybatis2</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-web</artifactId>
        </dependency>
        <dependency>
            <groupId>org.mybatis.spring.boot</groupId>
            <artifactId>mybatis-spring-boot-starter</artifactId>
            <version>2.2.0</version>
        </dependency>

        <dependency>
            <groupId>mysql</groupId>
            <artifactId>mysql-connector-java</artifactId>
            <scope>runtime</scope>
        </dependency>
        <!-- 引入druid数据源 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.8</version>
        </dependency>
        <!-- 需要引入log4j，因为druid使用了log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-test</artifactId>
            <scope>test</scope>
        </dependency>
    </dependencies>

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

</project>

【1.2】druid数据源配置

步骤1，引入 druid 依赖；

<!-- 引入druid数据源 -->
        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid</artifactId>
            <version>1.2.8</version>
        </dependency>
        <!-- 需要引入log4j，因为druid使用了log4j -->
        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
            <version>1.2.17</version>
        </dependency>

步骤3， 数据源druid配置； application.yml

# 配置springboot数据源
spring:
  datasource:
    username: root
    password: root
    url: jdbc:mysql://192.168.163.204:3306/mybatis
    driver-class-name: com.mysql.cj.jdbc.Driver
    type: com.alibaba.druid.pool.DruidDataSource  # 启用druid数据源
    #   数据源其他配置
    initialSize: 6
    minIdle: 6
    maxActive: 26
    maxWait: 60000
    timeBetweenEvictionRunsMillis: 60000
    minEvictableIdleTimeMillis: 300000
    testWhileIdle: true
    testOnBorrow: false
    testOnReturn: false
    poolPreparedStatements: true
    #   配置监控统计拦截的filters，去掉后监控界面sql无法统计，'wall'用于防火墙
    filters: stat,wall,log4j
    maxPoolPreparedStatementPerConnectionSize: 20
    useGlobalDataSourceStat: true
    connectionProperties: druid.stat.mergeSql=true;druid.stat.slowSqlMillis=500

druid 监控servlet配置；

// 导入druid数据源
@Configuration
public class DruidConfig {

    @ConfigurationProperties(prefix = "spring.datasource")
    @Bean
    public DataSource druid() {
        return new DruidDataSource();
    }

    // 配置druid监控
    // 1 配置一个管理后台的servlet
    @Bean
    public ServletRegistrationBean statViewServlet() {
        ServletRegistrationBean bean = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");
        // 配置相关参数
        Map<String, String> params = new HashMap<>();
        params.put("loginUsername", "admin");
        params.put("loginPassword", "admin");
        params.put("allow", "localhost"); // 默认允许所有访问
        params.put("deny", "192.168.163.204"); // 默认允许所有访问
        bean.setInitParameters(params);
        return bean;
    }

    // 2 配置一个监控的filter
    @Bean
    public FilterRegistrationBean webStatFilter() {
        FilterRegistrationBean bean = new FilterRegistrationBean<>();
        bean.setFilter(new WebStatFilter());
        // 配置相关参数
        Map<String, String> params = new HashMap<>();
        params.put("exclusions", "*.js,*.css,/druid/*");
        bean.setInitParameters(params);
        bean.setUrlPatterns(Arrays.asList("/*"));
        return bean;
    }
}

【1.3】数据库表与javabean

步骤1，数据库表

CREATE TABLE `employee` (
  `id` int NOT NULL AUTO_INCREMENT,
  `last_name` varchar(255) DEFAULT NULL,
  `email` varchar(255) DEFAULT NULL,
  `gender` int DEFAULT NULL,
  `d_id` int DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=2 DEFAULT CHARSET=utf8mb3
;

CREATE TABLE `department` (
  `id` int NOT NULL AUTO_INCREMENT,
  `department_name` varchar(255) DEFAULT NULL,
  PRIMARY KEY (`id`)
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8mb3
;

步骤2，编写db表映射的javabean；


public class Department {
    private Integer id;
    private String departmentName;

    public Department(){}
    public Integer getId() {
        return id;
    }

    public void setId(Integer id) {
        this.id = id;

        MybatisAutoConfiguration conf = null;
    }

    public String getDepartmentName() {
        return departmentName;
    }

    public void setDepartmentName(String departmentName) {
        this.departmentName = departmentName;
    }

    @Override
    public String toString() {
        return "Department{" +
                "id=" + id +
                ", departmentName='" + departmentName + '\\'' +
                '}';
    }
}


public class Employee {
    private Integer id;
    private String lastName;
    private Integer gender;
    private String email ;
    private Integer dId;

    public Employee(){}
    .............
}

【1.4】mybatis全局配置与sql映射

步骤1，mybatic全局配置类（也可以通过 mybatis-config.xml 来实现）;

@MapperScan 注解用于扫描 传入包下的所有Mapper类；

@org.springframework.context.annotation.Configuration
@MapperScan("com.cmc.springbt.mapper")
public class MyBatisConfig {

    @Bean
    public ConfigurationCustomizer configurationCustomizer() {
        return new ConfigurationCustomizer() {
            @Override
            public void customize(Configuration configuration) {
                configuration.setMapUnderscoreToCamelCase(true); // 开启驼峰
            }
        };
    }
}

步骤2，编写 mybatis maper，sql操作接口；

MybatisConfig 中的注解 MapperScan 已经可以扫描到 DepartmentMapper， 这里无需 添加@Mapper 注解； 两者取1 即可；

// 指定这是一个操作数据库的mapper
//@Mapper
public interface DepartmentMapper {
    @Select("select * from department where id=#{id} ")
    public Department getDeptByID(int id);

    @Delete("delete from department where id=#{id}")
    public int deleteDeptById(int id) ;

    @Insert("insert into department(department_name) values(#{departmentName})")
    @Options(useGeneratedKeys = true,keyProperty = "id")
    public int insertDept(Department dept);

    @Update("update department set department_name=#{departmentName} where id=#{id}")
    public int updateDept(Department dept);
}

【1.5】用户请求controller处理，使用 DepartmentMapper

步骤1，请求controller处理

@@RestController
public class DeptController {
    @Autowired
    DepartmentMapper departmentMapper;

    @GetMapping("dept/{id}")
    public Department getDepartment(@PathVariable("id") Integer id) {
        return departmentMapper.getDeptByID(id);
    }
    @GetMapping("dept")
    public Department insertDept(Department dept) {
        departmentMapper.insertDept(dept);
        return dept;
    }
}

注意，这是 @RestController， 而不是 @Controller；因为我是写数据到servlet，而不是到某个具体视图；

步骤2，修改springboot web项目配置（或有）；

application.properties  

# 服务器配置
server.port=8085
server.servlet.context-path=/springbt-mybatis2

小结，整体项目结构

【1.6】访问效果

http://localhost:8085/springbt-mybatis2/dept?departmentName=zhangsan01
http://localhost:8085/springbt-mybatis2/dept/13 http://localhost:8085/springbt-mybatis2/dept/13

 

 【2】springboot使用配置引入mybatis

【2.1】 编写mybatis全局配置与sql文件

mybatis-config.xml 全局配置文件

<?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="mapUnderscoreToCamelCase" value="true"/>
    </settings>
</configuration>

【2.2】sql接口与sql映射文件

EmployeeMapper.java

// @Mapper 或  @MapperScan 把接口扫描装配到容器中
public interface EmployeeMapper {
    public Employee getEmpById(Integer id);

    public void insertEmp(Employee empt);
}
<?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.cmc.springbt.mapper.EmployeeMapper">
    <!--  通过id查询emp -->
    <select id="getEmpById" resultType="com.cmc.springbt.bean.Employee">
        SELECT id, last_name, email, gender, d_id
          FROM employee
         where id = #{id}
    </select>
    <!-- 插入emp -->
    <insert id="insertEmp">
        INSERT INTO employee
            (last_name, email, gender, d_id)
        VALUES(#{lastName}, #{email}, #{gender}, #{dID})
    </insert>

</mapper>

【2.3】在 application.yml 中指定 mybatis配置

# 配置mybatis 全局配置文件和mapper路径
mybatis:
  config-location: classpath:mybatis/mybatis-config.xml
  mapper-locations: classpath:mybatis/mapper/*.xml

【2.4】编写 EmpController处理 employee请求

@RestController
public class EmpController {
    @Autowired
    EmployeeMapper employeeMapper;

    @GetMapping("/emp/{id}")
    public Employee getEmp(@PathVariable("id") Integer id) {
        return employeeMapper.getEmpById(id);
    }
}

小结， mybatis配置后的整体目录结构；

 【2.5】访问效果

http://localhost:8085/springbt-mybatis2/emp/1

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