It can be solved by using property configuration files
1. Add a property file, such as config.propertiest, and define the key-value pair dao.prefix=.
2. Configure this property file in the spring configuration file.
3. You can use attributes file variables in <bean>, such as ${dao.prefix}
4. Selective injection can be done in service:

<bean id='sysService' class='com.alan.***Impl>
    <property name='***' ref='system${dao.prefix}Dao'>
</bean>
<bean id='systemDao' class='***'/>
<bean id='systemDubboDao class='***'/>
<bean id='systemOtherDao class='***'/>

这样配置的话，就会根据dao.prefix的值来决定注入哪一个DAO了。当dao.prefix=null(即什么都不填是），ref='systemDao'。关键在于bean命名的规律性。

You can use Spring's profile to solve this problem. Profiles can be used to correspond to different configurations (such as database configuration) in different environments to meet your needs.

The following configures three different attributes of the same bean under three profiles (dev, test, product):

<beans profile="dev">
    <bean id="systemUserService" class="com.alan.SystemUserServiceImpl">
        <property name="exm1" ref="exm1"></property>
    </bean>
</beans>
<beans profile="test">
    <bean id="systemUserService" class="com.alan.SystemUserServiceImpl">
        <property name="exm2" ref="exm2"></property>
    </bean>
</beans>
<beans profile="product">
    <bean id="systemUserService" class="com.alan.SystemUserServiceImpl">
        <property name="exm3" ref="exm3"></property>
    </bean>
</beans>

How to enable a profile when the program starts? There are many ways, just choose one:

Code method

AnnotationConfigApplicationContext ctx = new AnnotationConfigApplicationContext();
ctx.getEnvironment().setActiveProfiles("dev");

java command-Dspring.profiles.active="dev"

java -jar test.jar -Dspring.profiles.active="dev"

web.xml

If it is a web project, you can configure web.xml

<context-param>
    <param-name>spring.profiles.active</param-name>
    <param-value>dev</param-value>
</context-param>

Starting with different profiles will load different beans and different configurations.

SystemUserServiceImpl implements InitializingBean, ApplicationContextAware {
    private ApplicationContext applicationContext;
    public void afterPropertiesSet() throws java.lang.Exception {
        if (***) {
            this.exm1 = applicationContext.getBean("exap1");
        } else {
            this.exm2 = applicationContext.getBean("exap2");
        }
    }

    public void setApplicationContext(ApplicationContext ctx) throws BeansException {
        this.applicationContext= ctx;
    }
}

I don’t know if spel can solve the problem, you can search it and see