springboot mybatis 动态数据源切换 切面 mybatisplus 动态数据源

MyBatis Plus动态数据源

• 简述
• 工程搭建

• 1. 创建Maven工程
• 2. 依赖导入
• 3. 编写配置文件
• 4. 数据源
• 5. 选择数据源注解
• 6. 编写AOP切面
• 5. 编写测试类

简述

Mybatis plus动态获取数据源，获取不同数据库连接，这篇文章编写是通过一个注解指定方法去获取那个数据。

工程搭建

1. 创建Maven工程

2. 依赖导入

<dependencies>

        <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>
        </dependency>


        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-aop</artifactId>
        </dependency>

        <!--   多数据源依赖     -->
        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>dynamic-datasource-spring-boot-starter</artifactId>
            <version>3.4.1</version>
        </dependency>

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

        <dependency>
            <groupId>com.baomidou</groupId>
            <artifactId>mybatis-plus-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>druid-spring-boot-starter</artifactId>
        </dependency>

        <dependency>
            <groupId>org.projectlombok</groupId>
            <artifactId>lombok</artifactId>
        </dependency>

        <dependency>
            <groupId>com.alibaba</groupId>
            <artifactId>fastjson</artifactId>
        </dependency>

        <dependency>
            <groupId>cn.hutool</groupId>
            <artifactId>hutool-all</artifactId>
        </dependency>

        <dependency>
            <groupId>log4j</groupId>
            <artifactId>log4j</artifactId>
        </dependency>

    </dependencies>

父类依赖导入的版本如下

<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.0</version>
        <relativePath/>
    </parent>

3. 编写配置文件

application.yml

server:
  port: 8080

spring:
  application:
    name: mwb

mybatis-plus:
  mapper-locations: classpath:mapper/*.xml
  configuration:
    log-impl: org.apache.ibatis.logging.stdout.StdOutImpl

数据库连接配置文件：db.properties

spring.datasource.configLocationPath=mybatis-config.xml

# master
spring.datasource.master.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.master.jdbc-url=jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai&useSSL=false
spring.datasource.master.username=root
spring.datasource.master.password=数据库密码

# master 配置
spring.datasource.master.aliasesPackagePath=com.mai.bin.entity.master
spring.datasource.master.mapperPath=classpath:mapper/master/*.xml



# slave
spring.datasource.slave.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.slave.jdbc-url=jdbc:mysql://localhost:3306/ego?useUnicode=true&characterEncoding=utf-8&serverTimezone=Asia/Shanghai&useSSL=false
spring.datasource.slave.username=root
spring.datasource.slave.password=数据库密码

# slave 配置
spring.datasource.slave.aliasesPackagePath=com.mai.bin.entity.slave
spring.datasource.slave.mapperPath=classpath:mapper/slave/*.xml

4. 数据源

创建DataSourceConfig配置类

@Configuration
@PropertySource("classpath:db.properties")
public class DataSourceConfig {

    /**
     * 数据源 一
     */
    @Bean("master")
    @ConfigurationProperties(prefix = "spring.datasource.master")
    public DataSource masterDataSource(){
        return DataSourceBuilder.create().build();
    }

    /**
     * 数据源 二
     */
    @Bean("slave")
    @ConfigurationProperties(prefix = "spring.datasource.slave")
    public DataSource slaveDataSource(){
        return DataSourceBuilder.create().build();
    }

    /**
     * 主数据源
     */
    @Primary
    @Bean
    public MyDynamicDataSource dataSource(
            @Qualifier("master") DataSource master,
            @Qualifier("slave") DataSource slave){

        HashMap<String, DataSource> targetDataSource = new HashMap<>();
        targetDataSource.put("master", master);
        targetDataSource.put("slave", slave);

        return new MyDynamicDataSource(master, targetDataSource);
    }
}

创建自定动态数据源MyDynamicDataSource

public class MyDynamicDataSource extends AbstractRoutingDataSource {

    private static final ThreadLocal<String> source = new InheritableThreadLocal<>();

    public MyDynamicDataSource(DataSource defaultDataSource, Map<String, DataSource> targetDataSources){
        super.setDefaultTargetDataSource(defaultDataSource);
        super.setTargetDataSources(new HashMap<>(targetDataSources));
    }

    /**
     *  返回当前dataSourceKey值
     */
    @Override
    protected Object determineCurrentLookupKey() {
        return source.get();
    }

    // 设置 dataSourceKey 的值
    public static void setDataSource(String dataSource){
        source.set(dataSource);
    }

    // 清除 dataSourceKey 的值
    public static void toDefault(){
        source.remove();
    }
}

动态数据源的获取需要继承AbstractRoutingDataSource类，重写determineCurrentLookupKey方法获取当前数据连接，这里用到ThreadLocal类，保证线程安全。

5. 选择数据源注解

@Documented
@Retention(RetentionPolicy.RUNTIME)
@Target({ElementType.METHOD, ElementType.TYPE})
public @interface ChoiceDataSource {
    
    // 默认选择主数据源   
    String value() default "master";
}

6. 编写AOP切面

@Aspect
@Component
@Order(-1)
public class DataSourceAspect {

    @Pointcut("@annotation(com.mai.bin.annotation.ChoiceDataSource)")
    // 这个注解是意思是controller下所有方法都切入
//    @Pointcut("execution(* com.mai.bin.controller..*.*(..))")
    public void choiceDataSource(){

    }

    @Around(value = "choiceDataSource()")
    public Object choiceDataSourceAround(ProceedingJoinPoint point){

        try {

            // 获取方法
            Method method = ((MethodSignature) point.getSignature()).getMethod();

            // 检查方法上是否存在选择数据源的注解，没有就主数据源
            ChoiceDataSource choiceDataSource = method.getAnnotation(ChoiceDataSource.class);

            System.out.println("choiceDataSource: " + choiceDataSource);

            if (ObjectUtil.isNotEmpty(choiceDataSource)){

                System.out.println("进入choiceDataSource....");

                // 设置注解里面的数据源
                MyDynamicDataSource.setDataSource(choiceDataSource.value());
                System.out.println("dataSource " + choiceDataSource.value());

            }

            // 运行目标方法
            Object result = point.proceed();
            return result;

        } catch (Throwable e) {
            e.printStackTrace();
        }finally {
            // ThreadLocal 需要释放资源
            MyDynamicDataSource.toDefault();
        }

        return null;
    }


}

上面代码意思就是创建切面，同过注解方法实现，环绕通知跟反射确定方法中是否存在选择数据源注解，注解value有值，则进行选择，否则默认为主数据源。
注意： 记得进行资源释放，不然ThreadLocal会造成内存泄漏。

5. 编写测试类

entity、mapper层这里忽略过，controller层如下

==注意：==UserController对应是slave进行测试，TestIndexController对应是master进行测试。

UserController

@RestController
public class UserController {

    @Autowired
    @Qualifier("userMapper")
    private UserMapper userMapper;

    @ChoiceDataSource("slave")
    @RequestMapping("user/{id}")
    public String user(@PathVariable("id") Integer id){

        return userMapper.selectByIdUser(id).toString();

    }

}

TestIndexController

@RestController
public class TestIndexController {

    @Autowired
    @Qualifier("testIndexMapper")
    private TestIndexMapper testIndexMapper;

    @ChoiceDataSource("master")
    @RequestMapping("/testIndex/{id}")
    public String testIndex(@PathVariable("id") Integer id){

        return testIndexMapper.selectAllById1(id).toString();

    }

    /**
     * 测试默认值
     */
    @ChoiceDataSource()
    @RequestMapping("/testIndex2/{id}")
    public String testIndex2(@PathVariable("id") Integer id){

        return testIndexMapper.selectAllById1(id).toString();

    }

}

编写主启动类
需要去除自动装配数据源

@SpringBootApplication(exclude = {DataSourceAutoConfiguration.class})
@MapperScan({"com.mai.bin.mapper"})
public class Test08Main {

    public static void main(String[] args) {

        SpringApplication.run(Test08Main.class, args);

    }
}

测试结果

有错误或者更好的实现方法，欢迎交流！！！