下面是实际调试通过的例子，包含下面4个步骤：

（1）第一步，添加Maven依赖

根据官网Quick Start展示的依赖，在项目pom.xml中添加后各种找不到类引用。于是查看Spring Session项目的build.gradle文件，居然没有配置依赖的项目，难道还要我自己去找它的依赖，太不专业了吧？！！！

<dependencies>
 <dependency>
 <groupId>org.springframework.session</groupId>
 <artifactId>spring-session</artifactId>
 <version>1.0.1.RELEASE</version>
 </dependency>
</dependencies>

终于在多番仔细研究Spring Session项目源码之后，看到了spring-session-data-redis项目：

apply from: JAVA_GRADLE
apply from: MAVEN_GRADLE

apply plugin: 'spring-io'

description = "Aggregator for Spring Session and Spring Data Redis"

dependencies {
 compile project(':spring-session'),
 "org.springframework.data:spring-data-redis:$springDataRedisVersion",
 "redis.clients:jedis:$jedisVersion",
 "org.apache.commons:commons-pool2:$commonsPoolVersion"

 springIoVersions "io.spring.platform:platform-versions:${springIoVersion}@properties"
}

<dependency>
    <groupId>org.springframework.session</groupId>
    <artifactId>spring-session-data-redis</artifactId>
    <version>1.0.1.RELEASE</version>
</dependency>

import org.springframework.context.annotation.Bean;
import org.springframework.data.redis.connection.RedisConnectionFactory;
import org.springframework.data.redis.connection.jedis.JedisConnectionFactory;
import org.springframework.session.data.redis.config.annotation.web.http.EnableRedisHttpSession;

@EnableRedisHttpSession(maxInactiveIntervalInSeconds = 7200)
public class RedisHttpSessionConfig {

 @Bean
 public RedisConnectionFactory connectionFactory() {
 JedisConnectionFactory connectionFactory = new JedisConnectionFactory();
 connectionFactory.setPort(6379);
 connectionFactory.setHostName("10.18.15.190");
 return connectionFactory;
 }
}

（3）第三步，将RedisHttpSessionConfig加入到 WebInitializer#getRootConfigClasses()中，让Spring容器加载RedisHttpSessionConfig 类。WebInitializer是一个自定义的 AbstractAnnotationConfigDispatcherServletInitializer实现类，该类会在Servlet启动时加载 （当然也可以采用别的加载方法，比如采用扫描@Configuration注解类的方式等等）。

//该类采用Java Configuration，来代替web.xml 
public class WebInitializer extends AbstractAnnotationConfigDispatcherServletInitializer {
 
 @Override
 protected Class<?>[] getRootConfigClasses() {
 return new Class[]{Config1.class, Config2.class, RedisHttpSessionConfig.class};
 }
 
 //......
}

import org.springframework.session.web.context.AbstractHttpSessionApplicationInitializer;

public class SpringSessionInitializer extends AbstractHttpSessionApplicationInitializer {
}

（1）前面集成spring-sesion的第二步中，编写了一个配置类RedisHttpSessionConfig，它包含注解 @EnableRedisHttpSession，并通过@Bean注解注册了一个RedisConnectionFactory到Spring容器中。

而@EnableRedisHttpSession注解通过Import，引入了RedisHttpSessionConfiguration配 置类。该配置类通过@Bean注解，向Spring容器中注册了一个 SessionRepositoryFilter（SessionRepositoryFilter的依赖关 系：SessionRepositoryFilter --> SessionRepository --> RedisTemplate --> RedisConnectionFactory）。

package org.springframework.session.data.redis.config.annotation.web.http; @Configuration @EnableScheduling public class RedisHttpSessionConfiguration implements ImportAware, BeanClassLoaderAware { //...... @Bean public RedisTemplate<String,ExpiringSession> sessionRedisTemplate(RedisConnectionFactory connectionFactory) { //...... return template; } @Bean public RedisOperationsSessionRepository sessionRepository(RedisTemplate<String, ExpiringSession> sessionRedisTemplate) { //...... return sessionRepository; } @Bean public <S extends ExpiringSession> SessionRepositoryFilter<? extends ExpiringSession> springSessionRepositoryFilter(SessionRepository<S> sessionRepository, ServletContext servletContext) { //...... return sessionRepositoryFilter; } //...... }

package org.springframework.session.web.context; /** * Registers the {@link DelegatingFilterProxy} to use the * springSessionRepositoryFilter before any other registered {@link Filter}. * * ...... */ @Order(100) public abstract class AbstractHttpSessionApplicationInitializer implements WebApplicationInitializer { private static final String SERVLET_CONTEXT_PREFIX = "org.springframework.web.servlet.FrameworkServlet.CONTEXT."; public static final String DEFAULT_FILTER_NAME = "springSessionRepositoryFilter"; //...... public void onStartup(ServletContext servletContext) throws ServletException { beforeSessionRepositoryFilter(servletContext); if(configurationClasses != null) { AnnotationConfigWebApplicationContext rootAppContext = new AnnotationConfigWebApplicationContext(); rootAppContext.register(configurationClasses); servletContext.addListener(new ContextLoaderListener(rootAppContext)); } insertSessionRepositoryFilter(servletContext);//注册一个SessionRepositoryFilter afterSessionRepositoryFilter(servletContext); } /** * Registers the springSessionRepositoryFilter * @param servletContext the {@link ServletContext} */ private void insertSessionRepositoryFilter(ServletContext servletContext) { String filterName = DEFAULT_FILTER_NAME;//默认名字是springSessionRepositoryFilter DelegatingFilterProxy springSessionRepositoryFilter = new DelegatingFilterProxy(filterName);//该Filter代理会在初始化时从Spring容器中查找springSessionRepositoryFilter，之后实际会使用SessionRepositoryFilter进行doFilter操作 String contextAttribute = getWebApplicationContextAttribute(); if(contextAttribute != null) { springSessionRepositoryFilter.setContextAttribute(contextAttribute); } registerFilter(servletContext, true, filterName, springSessionRepositoryFilter); } //...... }

注意下面给出的是简化过的示例代码，与spring-session项目的源代码有所差异。

@Order(SessionRepositoryFilter.DEFAULT_ORDER) public class SessionRepositoryFilter implements Filter { public doFilter(ServletRequest request, ServletResponse response, FilterChain chain) { HttpServletRequest httpRequest = (HttpServletRequest) request; SessionRepositoryRequestWrapper customRequest = new SessionRepositoryRequestWrapper(httpRequest); chain.doFilter(customRequest, response, chain); } // ... }

public class SessionRepositoryRequestWrapper extends HttpServletRequestWrapper { public SessionRepositoryRequestWrapper(HttpServletRequest original) { super(original); } public HttpSession getSession() { return getSession(true); } public HttpSession getSession(boolean createNew) { // create an HttpSession implementation from Spring Session } // ... other methods delegate to the original HttpServletRequest ... }

package org.springframework.web; @HandlesTypes(WebApplicationInitializer.class) public class SpringServletContainerInitializer implements ServletContainerInitializer { /** * Delegate the {@code ServletContext} to any {@link WebApplicationInitializer} * implementations present on the application classpath. * * <p>Because this class declares @{@code HandlesTypes(WebApplicationInitializer.class)}, * Servlet 3.0+ containers will automatically scan the classpath for implementations * of Spring's {@code WebApplicationInitializer} interface and provide the set of all * such types to the {@code webAppInitializerClasses} parameter of this method. * * <p>If no {@code WebApplicationInitializer} implementations are found on the * classpath, this method is effectively a no-op. An INFO-level log message will be * issued notifying the user that the {@code ServletContainerInitializer} has indeed * been invoked but that no {@code WebApplicationInitializer} implementations were * found. * * <p>Assuming that one or more {@code WebApplicationInitializer} types are detected, * they will be instantiated (and <em>sorted</em> if the @{@link * org.springframework.core.annotation.Order @Order} annotation is present or * the {@link org.springframework.core.Ordered Ordered} interface has been * implemented). Then the {@link WebApplicationInitializer#onStartup(ServletContext)} * method will be invoked on each instance, delegating the {@code ServletContext} such * that each instance may register and configure servlets such as Spring's * {@code DispatcherServlet}, listeners such as Spring's {@code ContextLoaderListener}, * or any other Servlet API componentry such as filters. * * @param webAppInitializerClasses all implementations of * {@link WebApplicationInitializer} found on the application classpath * @param servletContext the servlet context to be initialized * @see WebApplicationInitializer#onStartup(ServletContext) * @see AnnotationAwareOrderComparator */ @Override public void onStartup(Set<Class<?>> webAppInitializerClasses, ServletContext servletContext) throws ServletException { //...... } }

（1）Http Session数据在Redis中是以Hash结构存储的。

127.0.0.1:6379> keys *
1) "spring:session:expirations:1431577740000"
2) "spring:session:sessions:e2cef3ae-c8ea-4346-ba6b-9b3b26eee578"
127.0.0.1:6379> type spring:session:sessions:e2cef3ae-c8ea-4346-ba6b-9b3b26eee578
hash
127.0.0.1:6379> type spring:session:expirations:1431577740000
set

127.0.0.1:6379> keys *
1) "spring:session:expirations:1431527520000"
2) "spring:session:sessions:59f3987c-d1e4-44b3-a83a-32079942888b"
3) "spring:session:sessions:11a69da6-138b-42bc-9916-60ae78aa55aa"
4) "spring:session:sessions:0a51e2c2-4a3b-4986-a754-d886d8a5d42d"
5) "spring:session:expirations:1431527460000"

127.0.0.1:6379> hkeys spring:session:sessions:59f3987c-d1e4-44b3-a83a-32079942888b
1) "maxInactiveInterval"
2) "creationTime"
3) "lastAccessedTime"
4) "sessionAttr:attr1"

127.0.0.1:6379> hget spring:session:sessions:59f3987c-d1e4-44b3-a83a-32079942888b sessionAttr:attr1
"\xac\xed\x00\x05sr\x00\x11java.lang.Integer\x12\xe2\xa0\xa4\xf7\x81\x878\x02\x00\x01I\x00\x05valuexr\x00\x10java.lang.Number\x86\xac\x95\x1d\x0b\x94\xe0\x8b\x02\x00\x00xp\x00\x00\x00\x03"

127.0.0.1:6379> hget spring:session:sessions:59f3987c-d1e4-44b3-a83a-32079942888b creationTime
"\xac\xed\x00\x05sr\x00\x0ejava.lang.Long;\x8b\xe4\x90\xcc\x8f#\xdf\x02\x00\x01J\x00\x05valuexr\x00\x10java.lang.Number\x86\xac\x95\x1d\x0b\x94\xe0\x8b\x02\x00\x00xp\x00\x00\x01MM\x94(\xec"