一、简介
对于数据访问层，无论是 SQL 还是 MySQL，SpringBoot 默认采用整合 Spring Data 的方式进行统一处理，添加了大量自动配置，屏蔽了很多设置，引入各自 xxxTemplate、xxxRepository 来简化我们对数据访问层的操作。对我们来说，只需要进行简单的设置即可
二、整合JDBC与数据源
1. JDBC
<dependencies>
<!-- JDBC -->
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-jdbc</artifactId>
</dependency>
<!-- MySQL 驱动 -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<scope>runtime</scope>
</dependency>
</dependencies>
导入 application.yml 配置文件，由于使用的 mysql 驱动的版本是 8，版本较高，因此需要作如下配置，尤其是 url 和 driver-class-name，否则会报错
spring:
datasource:
username: root
password: root
url: jdbc:mysql://localhost:3306/mybatis?useSSL=true&serverTimezone=GMT
driver-class-name: com.mysql.cj.jdbc.Driver
数据源的相关配置都是在 DataSourceProperties 中进行配置的
三、整合Druid数据源
1. 导入Druid数据源的pom文件
<!-- 引入 druid 数据源 -->
<dependency>
<groupId>com.alibaba</groupId>
<artifactId>druid</artifactId>
<version>1.1.13</version>
</dependency>
2. 配置Druid的配置文件
application.yml
spring:
datasource:
# 数据源的基本配置
username: root
password: root
url: jdbc:mysql://localhost:3306/mybatis?useSSL=true&serverTimezone=GMT
driver-class-name: com.mysql.cj.jdbc.Driver
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
3. 配置Druid数据源的监控
创建一个 DruidConfig 类，在里面分别配置 Config、Servlet 和 Filter
Config
将 Druid 的配置文件引入进来
// 从配置文件加载 druid 的配置信息
@ConfigurationProperties(prefix = "spring.datasource")
@Bean
public DataSource druid() {
return new DruidDataSource();
}
Servlet：配置一个管理后台的 Servlet
需要返回一个 ServletRegistrationBean 的对象，并设置该对象的属性，包括监控登陆的用户名和密码等
@Bean
public ServletRegistrationBean statViewServlet() {
ServletRegistrationBean bean
= new ServletRegistrationBean(new StatViewServlet(), "/druid/*");
Map<String, String> initParam = new HashMap<>();
initParam.put("loginUsername", "admin");
initParam.put("loginPassword", "123456");
initParam.put("allow", ""); // 默认允许所有访问
bean.setInitParameters(initParam);
return bean;
}
Filter：配置一个管理数据源监控的 Filter
需要返回一个 FilterRegistrationBean 的对象
@Bean
public FilterRegistrationBean webStatFilter() {
FilterRegistrationBean bean
= new FilterRegistrationBean();
// 设置 Filter
bean.setFilter(new WebStatFilter());
Map<String, String> initParam = new HashMap<>();
// 不过滤 *.js、*.css ...
initParam.put("exclusions", "*.js,*.css,/druid/*");
bean.setInitParameters(initParam);
bean.setUrlPatterns(Arrays.asList("/*"));
return bean;
}
4. 启动
在浏览器的地址栏中输入 http://localhost:8080/druid/index.html，会出现以下的页面
四、整合MyBatis
需要的 pom 文件
<dependency>
<groupId>org.mybatis.spring.boot</groupId>
<artifactId>mybatis-spring-boot-starter</artifactId>
<version>2.0.0</version>
</dependency>
依然需要配置好 druid 数据源，创建 JavaBean
4.1 注解版
首先创建一个 Mapper 接口，需要在接口名上添加 @Mapper 注解，然后编写抽象方法，需要注意的是，此时增删改查语句直接写在方法名上，如果需要传递参数，则和 MyBatis 一样，使用 #{xxx} 传递参数
@Mapper
public interface EmployeeMapper {
@Select("select id, last_name lastName, gender, email, dept_id deptId from employee")
List<Employee> getAllEmps();
@Select("select id, last_name lastName, gender, email, dept_id deptId from employee where id = #{empId}")
Employee getAllEmp(Integer empId);
@Delete("delete from employee where id = #{empId}")
int deleteEmplById(Integer empId);
@Delete("delete from employee")
int deleteEmps();
@Update("update employee set last_name = #{lastName} where id = #{id}")
int updateEmpById(Employee employee);
@Insert("insert into employee(id, last_name, gender, email, dept_id) values(#{id}, #{lastName}, #{gender}, #{email}, #{deptId})")
int insertEmp(Employee employee);
}
然后将 xxxMapper 类自动装配进测试类中，对抽象方法进行测试
@RunWith(SpringRunner.class)
@SpringBootTest
public class Springboot07DataMybatisApplicationTests {
@Autowired
EmployeeMapper employeeMapper;
@Test
public void contextLoads() {
System.out.println(employeeMapper.getAllEmp(1));
}
@Test
public void getAllEmps() {
List<Employee> allEmps = employeeMapper.getAllEmps();
System.out.println(allEmps);
}
@Test
public void insertEmp() {
Employee employee = new Employee();
employee.setId(1);
employee.setLastName("luwenhe");
employee.setEmail("[email protected]");
employee.setGender(1);
employee.setDeptId(1);
int i = employeeMapper.insertEmp(employee);
System.out.println(i);
}
@Test
public void updateEmployee() {
Employee employee = new Employee();
employee.setId(1);
employee.setLastName("xixixi");
int i = employeeMapper.updateEmpById(employee);
System.out.println(i);
}
@Test
public void deleteAll() {
int i = employeeMapper.deleteEmps();
System.out.println(i);
}
}
需要注意的是，这里如果不再 xxxMapper 接口名上面添加 @Mapper 注解，那么会出现以下的错误，表示 SpringBoot 无法找到对应的 xxxMapper 接口
Caused by: org.springframework.beans.factory.NoSuchBeanDefinitionException: No qualifying bean of type 'edu.just.springboot.mapper.EmployeeMapper' available: expected at least 1 bean which qualifies as autowire candidate. Dependency annotations: {@org.springframework.beans.factory.annotation.Autowired(required=true)}
解决的方法有2个：
-
第一种：直接在 xxxMapper 接口上面添加 @Mapper 注解
-
第二种：在主方法种添加
@MapperScan(包名)注解，即扫描 mapper 层下的所有接口@SpringBootApplication // 批量扫描所以 mapper 下的接口 @MapperScan("edu.just.springboot.mapper") public class Springboot07DataMybatisApplication { public static void main(String[] args) { SpringApplication.run(Springboot07DataMybatisApplication.class, args); } }
可以在配置类中设置 MyBatis 的自动驼峰命名转换，即将类似 user_name 转化成 userName 这种格式
在容器中添加一个 ConfigurationCustomizer 组件，重写其中的 customer 方法，并且设置驼峰命名法
@org.springframework.context.annotation.Configuration
public class MyBatisConfig {
@Bean
public ConfigurationCustomizer configurationCustomizer() {
return new ConfigurationCustomizer() {
@Override
public void customize(Configuration configuration) {
// 配置驼峰命名法
configuration.setMapUnderscoreToCamelCase(true);
}
};
}
}
4.2 配置版
如果不是直接在 Mapper 接口的抽象方法上面直接编写增删改查语句，也可以通过外部配置文件 xxxMapper.xml 来配置，类似于 SpringMVC 这种
首先在 mapper 包下创建一个名为 DepartmentMapper 的接口文件
@Mapper
public interface DepartmentMapper {
List<Department> getDepts();
Department getDeptById(Integer id);
Integer addDept(Department department);
Integer deleteDept(Integer id);
Integer updateDept(Department department);
}
在 resources 下的 mapper 文件下创建一个名为 DepartmentMapper.xml 的配置文件
<?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="edu.just.springboot.mapper.DepartmentMapper">
<select id="getDeptById" resultType="edu.just.springboot.bean.Department">
select id, depart_name departName from department where id = #{id}
</select>
<select id="getDepts" resultType="edu.just.springboot.bean.Department">
select id, depart_name departName from department
</select>
<insert id="addDept">
insert into department values(#{id}, #{departName})
</insert>
<delete id="deleteDept">
delete from department where id = #{id}
</delete>
<update id="updateDept">
update department set depart_name = #{departName} where id = #{id}
</update>
</mapper>
最后，需要在主配置文件中对上面的 mybatis 的配置文件进行映射
mybatis:
# 指定全局配置文件位置
config-location: classpath:mybatis-config.xml
# 指定sql映射文件位置
mapper-locations: classpath:mapper/*.xml
然后在测试类中进行测试：
@RunWith(SpringRunner.class)
@SpringBootTest
public class DepartmentMapperTest {
@Autowired
DepartmentMapper departmentMapper;
@Test
public void test1() {
Department deptById = departmentMapper.getDeptById(1);
System.out.println(deptById);
}
@Test
public void test2() {
List<Department> a = departmentMapper.getDepts();
System.out.println(a);
}
@Test
public void test3() {
Department department = new Department();
department.setId(100);
department.setDepartName("xixixi");
departmentMapper.addDept(department);
}
@Test
public void test4() {
Integer integer = departmentMapper.deleteDept(100);
System.out.println(integer);
}
@Test
public void test5() {
Department department = new Department();
department.setId(1);
department.setDepartName("qwer");
Integer integer = departmentMapper.updateDept(department);
System.out.println(integer);
}
}