当Redis不可用时，java使用默认的Spring会话

Question

上下文：我正在尝试使用Spring的Redis会话来保存云上多个Tomcat的会话。但在某些环境下，Redis将不可用。我想配置一种方法，使我的应用程序能够根据运行时的环境返回默认实现

当我的环境中没有Redis时，我无法找到恢复默认spring会话配置的正确方法

我正在使用：

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
    <version>2.0.4.RELEASE</version>
</dependency>

当我扩展一个类时，我可以使用Redis会话（默认配置），如下所示：

public class RedisHttpSessionApplicationInitializer extends 
    AbstractHttpSessionApplicationInitializer {

}

当Redis不可用时，我尝试使用我的RedisHttpSessionApplicationInitializer的构造函数来加载SpringHttpSessionConfiguration，并在 SpringHttpSessionConfiguration和EnableSpringHttpSession

所以我做了如下修改：

public class RedisHttpSessionApplicationInitializer extends 
    AbstractHttpSessionApplicationInitializer {
        public RedisHttpSessionApplicationInitializer(){
            super(SpringHttpSessionConfiguration.class);
        }
 }

以及：

@Bean
public SessionRepository<MapSession> sessionRepository() {
    return new MapSessionRepository(new HashMap<>());
}

我仍然得到如下错误：

ERROR 921  [Thread 19] org.springframework.web.context.ContextLoader - 
Context initialization failed
org.springframework.beans.factory.UnsatisfiedDependencyException: 
Error creating bean with name 'springSessionRepositoryFilter' defined 
in org.springframework.session.config.annotation.web.http.SpringHttpSessionConfiguration: Unsatisfied dependency expressed through method 
'springSessionRepositoryFilter' parameter 0; nested exception is 
org.springframework.beans.factory.NoSuchBeanDefinitionException: No 
qualifying bean of type 
'org.springframework.session.SessionRepository<?>' available: expected 
at least 1 bean which qualifies as autowire candidate. Dependency 
annotations: {}
at org.springframework.beans.factory.support.ConstructorResolver.createArgumentArray(ConstructorResolver.java:723)
at org.springframework.beans.factory.support.ConstructorResolver.instantiateUsingFactoryMethod(ConstructorResolver.java:458)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.instantiateUsingFactoryMethod(AbstractAutowireCapableBeanFactory.java:1249)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBeanInstance(AbstractAutowireCapableBeanFactory.java:1098)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:545)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:502)
at org.springframework.beans.factory.support.AbstractBeanFactory.lambda$doGetBean$0(AbstractBeanFactory.java:312)
at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:228)
at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:310)
at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:200)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBea

你能建议我试一下我的用例吗？另外，如果你需要我提供更多信息，请告诉我

Answer 1

我能够解决的方法是使用CustomRedisHttpSessionConfiguration

@Configuration
public class CustomRedisHttpSessionConfiguration extends RedisHttpSessionConfiguration {

    @Override
    public void configureTasks(ScheduledTaskRegistrar taskRegistrar) {
        if (isRedisPresent()) {
            // Do something
        }else{
            // Do Something else
        }
     }

}

此外，为了初始化我的应用程序，我使用了以下命令：

public class RedisHttpSessionApplicationInitializer extends AbstractHttpSessionApplicationInitializer {

    @Override
    public void onStartup(ServletContext servletContext) throws ServletException {
        //...
    }
}