SpringBoot专题学习Part20：SpringBoot整合MyBatis的配置及使用 - 注解实现

Love The Way You Lie 2023-07-18 06:47 28阅读 0赞

SpringBoot整合MyBatis 使得对数据库的操作变得非常方便  
可用注解和配置文件这两种方式来实现  
注解方式相对而言会更加简单

**首先** 引入依赖：  
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用SpringBoot Initializer创建项目的时候 可以带上JDBC依赖 因为能够自动配置数据源

若不是用向导创建项目 则须手动引入依赖：

<dependency>
        <groupId>com.alibaba</groupId>
        <artifactId>druid</artifactId>
        <version>1.1.10</version>
    </dependency>
    
    
    <dependency>
        <groupId>org.slf4j</groupId>
        <artifactId>log4j-over-slf4j</artifactId>
        <version>1.7.25</version>
    </dependency>
    
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-jdbc</artifactId>
    </dependency>
    <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>2.1.2</version>
    </dependency>
    
    <dependency>
        <groupId>mysql</groupId>
        <artifactId>mysql-connector-java</artifactId>
        <scope>runtime</scope>
    </dependency>
    <dependency>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-test</artifactId>
        <scope>test</scope>
        <exclusions>
            <exclusion>
                <groupId>org.junit.vintage</groupId>
                <artifactId>junit-vintage-engine</artifactId>
            </exclusion>
        </exclusions>
    </dependency>

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当然 也可以不引 因为springboot mybatis的底层也引入了springboot jdbc

然后 需要配置好数据源  
我选用的是Druid数据源

yml配置文件：

spring:
      datasource:
        driver-class-name: com.mysql.cj.jdbc.Driver
        url: jdbc:mysql://127.0.0.1:3306/springboot_mybatis?useUnicode=true&useJDBCCompliantTimezoneShift=true&useLegacyDatetimeCode=false&serverTimezone=UTC
        username: root
        password: 123456
        initialization-mode: always
        type: com.alibaba.druid.pool.DruidDataSource
        #   数据源其他配置
        initialSize: 5
        minIdle: 5
        maxActive: 20
        maxWait: 60000
        timeBetweenEvictionRunsMillis: 60000
        minEvictableIdleTimeMillis: 300000
        validationQuery: SELECT 1 FROM DUAL
        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

**然后**创建配置类 对Druid进行配置：

@Configuration
    public class DruidConfig {
        
    
        @ConfigurationProperties(prefix = "spring.datasource")
        @Bean
        public DataSource druid()
        {
        
            return new DruidDataSource();
        }
    
        @Bean
        public ServletRegistrationBean statViewServlet()
        {
        
            ServletRegistrationBean<StatViewServlet> srb = new ServletRegistrationBean<>(new StatViewServlet(), "/druid/*");
            // 设置初始化参数
            Map<String,String> initParams=new HashMap<>();
            // 登录后台的用户名
            initParams.put("loginUsername","admin");
            // 登录后台的密码
            initParams.put("loginPassword","123456");
            // 允许访问的ip 默认或为空代表允许所有
            initParams.put("allow","");
            // 不允许访问的ip
            initParams.put("deny","111.111.111.111");
            srb.setInitParameters(initParams);
            return srb;
        }
    
        @Bean
        public FilterRegistrationBean webStatFilter()
        {
        
            FilterRegistrationBean<Filter> frb = new FilterRegistrationBean<>();
            // 传入Druid的监控Filter
            frb.setFilter(new WebStatFilter());
            // 设置初始化参数
            Map<String,String> initParams=new HashMap<>();
            // 设置哪些路径不进行拦截
            initParams.put("exclusions","*.js,*.css,/druid/*");
            frb.setInitParameters(initParams);
            // 设置拦截的请求
            frb.setUrlPatterns(Arrays.asList("/*"));
            return frb;
        }
    }

创建数据表和对应的bean类

**最后**就可以开始使用MyBatis了 注解方式非常简单：

Mapper类

// @Mapper注解 用于指定该接口类是一个操作数据库的mapper
    @Mapper
    public interface DepartmentMapper {
        
    
        // 单查询
        @Select("select * from department where id=#{id}")
        public Department getDeptmentById(Integer id);
    
        // 删除
        @Delete("delete from department where id=#{id}")
        public int deleteDeptmentById(Integer id);
    
        // 插入
        // @Options注解：配置是否使用自增主键 并指定自增主键 如此 当插入完成后 主键又会重新封装 就不会返回主键null了
        @Options(useGeneratedKeys = true,keyProperty = "id")
        @Insert("insert into department (departmentName) values(#{departmentName})")
        public int insertDepartment(Department department);
    
        // 更新
        @Update("update department set departmentName=#{departmentName} where id=#{id}")
        public int updateDepartment(Department department);
    }

使用`@Options`注解 指定了自增的主键 可以很好地防止非手动插入的主键展示成null  
直接注入进来即可使用 非常方便

测试：

@RestController
    public class DepartmentController {
        
    
        @Autowired
        DepartmentMapper departmentMapper;
    
        @GetMapping("/dept/{id}")
        public Department getDepartment(@PathVariable("id") Integer id)
        {
        
            return departmentMapper.getDeptmentById(id);
        }
    
        @GetMapping("/dept")
        public Department insertDepartment(Department department)
        {
        
            departmentMapper.insertDepartment(department);
            return department;
        }
    }

![在这里插入图片描述][20200325001310430.png]  
测试成功

--------------------

当数据库的字段名和bean的属性名对应不上时 字段不匹配 导致相应的数据就无法查询  
且注解方式没有xml配置文件 因而无法在xml文件中开启驼峰映射

此时 可以**自定义MyBatis的配置规则**  
自己创建一个MyBatis的配置类 添加到Spring容器中  
**在配置类中开启驼峰映射**

@org.springframework.context.annotation.Configuration
    public class MyBatisConfig {
        
    
        // 给容器中添加一个ConfigurationCustomizer定制配置
        @Bean
        public ConfigurationCustomizer configurationCustomizer()
        {
        
            return new ConfigurationCustomizer()
            {
        
                @Override
                public void customize(Configuration configuration) {
        
                    configuration.setMapUnderscoreToCamelCase(true);
                }
            };
        }
    }

--------------------

最后 还可以**批量扫描Mapper接口**  
在启动类上或是MyBatis的配置类上添加`@MapperScan`注解来扫描 参数传入要扫码的包的路径  
这样 Mapper类上就无须添加@Mapper注解了

// 扫描mapper包 这样 指定包下所有接口都相当于添加了@Mapper注解
    @MapperScan(value = "net.zjitc.springboot.mapper")
    @SpringBootApplication
    public class SpringbootMybatisApplication {
        
    
        public static void main(String[] args) {
        
            SpringApplication.run(SpringbootMybatisApplication.class, args);
        }
    }

--------------------

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[20200325001310430.png]: /images/20230528/d3a6b4ed32a742b58f41bcab71e3af06.png