SpringBoot专题学习Part21：SpringBoot整合MyBatis的配置及使用 - 配置文件实现

首先 引入依赖：

<!-- Druid数据源 -->
<dependency>
    <groupId>com.alibaba</groupId>
    <artifactId>druid</artifactId>
    <version>1.1.10</version>
</dependency>

<!-- 日志转换包 -->
<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>

然后 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
然后就可以开始配置了：

首先 写一个接口：
接口里面定义了要对数据库进行操作的curd方法
若没添加@MapperScan注解 则该接口类须加上@Mapper

public interface EmployeeMapper {

    public Employee getEmployeeById(Integer id);

    public void insertEmployee(Employee employee);
}

之后 配置MyBatis的全局配置文件：

<?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>

</configuration>

里面是空的 因为全局配置文件通常是用于配置数据源的
而数据源在上面已经配好了Druid的了

之后还需要配置SQL映射的配置文件：
映射配置文件放在resources资源目录下
名字通常取成xxxMapper.xml

<?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="net.zjitc.springboot.mapper.EmployeeMapper">
    <select id="getEmployeeById" resultType="net.zjitc.springboot.bean.Employee">
        select * from employee where id=#{id}
    </select>

    <insert id="insertEmployee">
        insert into employee(lastName,email,gender,d_id) values(#{lastName},#{email},#{gender},#{dId})
    </insert>
</mapper>

还需要在yml配置文件中进行配置(properties配置文件也行 只不过语法不太一样
配置的目的是为了让MyBatis知道这些配置文件的存在：

mybatis:
  # MyBatis全局配置文件的路径
  config-location: classpath:mybatis/mybatis-config.xml
  # MyBatis映射配置文件的路径
  mapper-locations: classpath:mybatis/mapper/*.xml

这样就配置完了

简单测试：

@RestController
public class EmployeeController {

    @Autowired
    EmployeeMapper employeeMapper;

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

测试成功

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当数据库的字段和bean的属性不一致时 获取的值是null
此时 可以配置驼峰映射

在MyBatis的全局配置文件中进行配置：

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

注解版的MyBatis和配置文件版的MyBatis可以共存 混合使用

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