分散式專案通常部署在不同的伺服器中，而傳統session只儲存在本地伺服器，並不能實現session的跨域使用。因此實現session一致性通常將sessio儲存到redis中，其他伺服器獲取回話資訊直接去redis中獲取。spring-session原理就是講獲取session的方式，從tomcate容器獲取改為了從redis中獲取。

現在spring-session整合redis:

pom.xml:在spring+springmvc基礎上：

<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
  <modelVersion>4.0.0</modelVersion>
  <groupId>cn.todd.spring</groupId>
  <artifactId>webmvc</artifactId>
  <version>0.0.1-SNAPSHOT</version>

   <dependencies>
	<dependency>
	    <groupId>org.springframework</groupId>
	    <artifactId>spring-context</artifactId>
	    <version>5.0.0.RELEASE</version>
	</dependency>
	<!--spring-web -->
	<dependency>
	    <groupId>org.springframework</groupId>
	    <artifactId>spring-web</artifactId>
	    <version>5.0.0.RELEASE</version>
	</dependency>
	<!-- spring-webmvc -->
	<dependency>
	    <groupId>org.springframework</groupId>
	    <artifactId>spring-webmvc</artifactId>
	    <version>5.0.0.RELEASE</version>
	</dependency>

	<!-- javax.servlet-api -->
	<dependency>
	    <groupId>javax.servlet</groupId>
	    <artifactId>javax.servlet-api</artifactId>
	    <version>4.0.0</version>
	    <scope>provided</scope>
	</dependency>
	<!-- https://mvnrepository.com/artifact/javax.servlet/jstl -->
	<dependency>
	    <groupId>javax.servlet</groupId>
	    <artifactId>jstl</artifactId>
	    <version>1.2</version>
	</dependency>
	
	<!-- spring整合spring-session實現快取一致性 -->	<!-- spring 整合redis -->
	<dependency>
	    <groupId>redis.clients</groupId>
	    <artifactId>jedis</artifactId>
	    <version>2.9.0</version>
	</dependency>
	<!-- https://mvnrepository.com/artifact/org.springframework.session/spring-session-data-redis -->
	<dependency>
	    <groupId>org.springframework.session</groupId>
	    <artifactId>spring-session-data-redis</artifactId>
	    <version>1.3.1.RELEASE</version>
	</dependency>


	<!--單元測試 -->
	<dependency>
	    <groupId>junit</groupId>
	    <artifactId>junit</artifactId>
	    <version>4.12</version>
	    <scope>test</scope>
	</dependency>
	<!-- logback日誌列印-->
	<dependency>
	    <groupId>ch.qos.logback</groupId>
	    <artifactId>logback-core</artifactId>
	    <version>1.2.3</version>
	</dependency>
	<dependency>
	    <groupId>ch.qos.logback</groupId>
	    <artifactId>logback-classic</artifactId>
	    <version>1.2.3</version>
	    <scope>test</scope>
	</dependency>
  </dependencies>
  
  <build>
		<plugins>
			<!-- 設定編譯版本為1.8 -->
			<plugin>
				<groupId>org.apache.maven.plugins</groupId>
				<artifactId>maven-compiler-plugin</artifactId>
				<configuration>
					<source>1.8</source>
					<target>1.8</target>
					<encoding>UTF-8</encoding>
				</configuration>
			</plugin>
		</plugins>
	</build>
</project>
 

	<!-- redis配置 -->
		<bean id="poolConfig" class="redis.clients.jedis.JedisPoolConfig">
		<property name="maxIdle" value="10" />
		<property name="maxTotal" value="5000" />
		<property name="testOnBorrow" value="true" />
	</bean> 
   <bean id="jedisConnectionFactory" class="org.springframework.data.redis.connection.jedis.JedisConnectionFactory">
  		<property name="hostName" value="localhost"></property>
  		<property name="port" value="6379"></property>
  		<property name="database" value="2"></property>
  		<property name="usePool" value="true"></property>	
  		<property name="poolConfig" ref="poolConfig"></property>
   </bean>
   
   <!-- httpsession配置 -->
   <bean id="redisHttpSession" class="org.springframework.session.data.redis.config.annotation.web.http.RedisHttpSessionConfiguration">
   		<property name="maxInactiveIntervalInSeconds" value="1600"></property>
   </bean>
   
 

<!-- springsession配置 -->
  <filter>
  	<filter-name>springSessionRepositoryFilter</filter-name>
  	<filter-class>org.springframework.web.filter.DelegatingFilterProxy</filter-class>
  </filter>
  <filter-mapping>
  	<filter-name>springSessionRepositoryFilter</filter-name>
  	<url-pattern>/*</url-pattern>
  </filter-mapping>
  
  
  
  <servlet>
  	<servlet-name>dispather</servlet-name>
  	<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
 	<init-param>  
         <param-name>contextConfigLocation</param-name>  
         <param-value>classpath:springmvc1.xml</param-value>  
     </init-param>  
    <load-on-startup>1</load-on-startup>  
  </servlet>
  <servlet-mapping>
  	<servlet-name>dispather</servlet-name>
  	<url-pattern>/</url-pattern>
  </servlet-mapping> 
 

基本完成，測試是不是將session資訊存到redis了：

@Controller
public class ItemsController3 {
	@RequestMapping("/query")
	public  ModelAndView query(HttpServletRequest request){
		request.getSession().setAttribute("name", "zhangsan");
		ModelAndView mv=new ModelAndView();
		mv.setViewName("item");
		return mv;
	}

}

我運行了3次，這樣回話就儲存到redis了。取的時候也是直接從redis中取的。

簡單原理：