Spring Session - HttpSession (Quick Start)

本指南描述了如何使用 Spring 会话以透明的方式利用 Redis 来支持基于 XML 配置的 Web 应用程序的 HttpSession。

This guide describes how to use Spring Session to transparently leverage Redis to back a web application’s HttpSession with XML-based configuration.

您可以在 httpsession-xml sample application 中找到完整指南。

You can find the completed guide in the httpsession-xml-sample.

Updating Dependencies

在使用 Spring 会话之前，您必须更新依赖。如果您使用 Maven，您必须添加以下依赖：

Before you use Spring Session, you must update your dependencies. If you use Maven, you must add the following dependencies:

pom.xml
<dependencies>
	<!-- ... -->

	<dependency>
		<groupId>org.springframework.session</groupId>
		<artifactId>spring-session-data-redis</artifactId>
		<version>{spring-session-version}</version>
		<type>pom</type>
	</dependency>
	<dependency>
		<groupId>io.lettuce</groupId>
		<artifactId>lettuce-core</artifactId>
		<version>{lettuce-core-version}</version>
	</dependency>
	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-web</artifactId>
		<version>{spring-core-version}</version>
	</dependency>
</dependencies>

Spring XML Configuration

在添加所需的依赖项后，我们可以创建我们的 Spring 配置。Spring 配置负责创建一个 Servlet 过滤器，该过滤器将 HttpSession 实现替换为由 Spring Session 支持的实现。为此，请添加以下 Spring 配置：

After adding the required dependencies, we can create our Spring configuration. The Spring configuration is responsible for creating a servlet filter that replaces the HttpSession implementation with an implementation backed by Spring Session. To do so, add the following Spring Configuration:

src/main/webapp/WEB-INF/spring/session.xml
Unresolved include directive in modules/ROOT/pages/guides/xml-redis.adoc - include::example$spring-session-samples/spring-session-sample-xml-redis/src/main/webapp/WEB-INF/spring/session.xml[]
1 We use the combination of <context:annotation-config/> and RedisHttpSessionConfiguration because Spring Session does not yet provide XML Namespace support (see gh-104). This creates a Spring Bean with the name of springSessionRepositoryFilter that implements Filter. The filter is in charge of replacing the HttpSession implementation to be backed by Spring Session. In this instance, Spring Session is backed by Redis.
2 We create a RedisConnectionFactory that connects Spring Session to the Redis Server. We configure the connection to connect to localhost on the default port (6379) For more information on configuring Spring Data Redis, see the {docs-url}/spring-data/data-redis/docs/{spring-data-redis-version}/reference/html/[reference documentation].

XML Servlet Container Initialization

我们的 Spring Configuration 创建了一个名为 springSessionRepositoryFilter 的 Spring Bean，它实现了 Filter。springSessionRepositoryFilter Bean 负责使用由 Spring Session 支持的自定义实现来替换 HttpSession。

Our httpsession-xml-spring-configuration created a Spring Bean named springSessionRepositoryFilter that implements Filter. The springSessionRepositoryFilter bean is responsible for replacing the HttpSession with a custom implementation that is backed by Spring Session.

为了让我们的 Filter 发挥作用，我们需要指示 Spring 加载我们的 session.xml 配置。我们可以通过以下配置来实现：

In order for our Filter to do its magic, we need to instruct Spring to load our session.xml configuration. We can do so with the following configuration:

src/main/webapp/WEB-INF/web.xml
Unresolved include directive in modules/ROOT/pages/guides/xml-redis.adoc - include::example$spring-session-samples/spring-session-sample-xml-redis/src/main/webapp/WEB-INF/web.xml[]
Unresolved include directive in modules/ROOT/pages/guides/xml-redis.adoc - include::example$spring-session-samples/spring-session-sample-xml-redis/src/main/webapp/WEB-INF/web.xml[]

{docs-url}/spring/docs/{spring-core-version}/spring-framework-reference/core.html#context-create[ContextLoaderListener] 读入 contextConfigLocation，并拾取到我们的 session.xml 配置。

The {docs-url}/spring/docs/{spring-core-version}/spring-framework-reference/core.html#context-create[ContextLoaderListener] reads the contextConfigLocation and picks up our session.xml configuration.

最后，我们需要确保我们的 Servlet 容器（即 Tomcat）针对每个请求使用我们的 springSessionRepositoryFilter。以下代码段为我们执行最后一步：

Last, we need to ensure that our Servlet Container (that is, Tomcat) uses our springSessionRepositoryFilter for every request. The following snippet performs this last step for us:

src/main/webapp/WEB-INF/web.xml
Unresolved include directive in modules/ROOT/pages/guides/xml-redis.adoc - include::example$spring-session-samples/spring-session-sample-xml-redis/src/main/webapp/WEB-INF/web.xml[]

{docs-url}/spring-framework/docs/{spring-core-version}/javadoc-api/org/springframework/web/filter/DelegatingFilterProxy.html[DelegatingFilterProxy] 按名称查找一个 Bean springSessionRepositoryFilter，并将其转换为 Filter。对于调用 DelegatingFilterProxy`的每个请求，都调用 `springSessionRepositoryFilter。

The {docs-url}/spring-framework/docs/{spring-core-version}/javadoc-api/org/springframework/web/filter/DelegatingFilterProxy.html[DelegatingFilterProxy] looks up a Bean by the name of springSessionRepositoryFilter and cast it to a Filter. For every request that DelegatingFilterProxy is invoked, the springSessionRepositoryFilter is invoked.

httpsession-xml Sample Application

本节介绍如何使用 httpsession-xml 示例应用程序。

This section describes how to work with the httpsession-xml sample application.

Running the httpsession-xml Sample Application

您可以获取 源代码 并调用以下命令运行示例：

You can run the sample by obtaining the source code and invoking the following command:

要让示例发挥作用，你必须在 localhost 上 install Redis 2.8+ 并使用默认端口 (6379) 运行它。或者，你可以更新 RedisConnectionFactory 以指向 Redis 服务器。另一个选项是使用 Docker 在 localhost 上运行 Redis。有关详细说明，请参见 Docker Redis repository。

For the sample to work, you must install Redis 2.8+ on localhost and run it with the default port (6379). Alternatively, you can update the RedisConnectionFactory to point to a Redis server. Another option is to use Docker to run Redis on localhost. See Docker Redis repository for detailed instructions.

 
$ ./gradlew :spring-session-sample-xml-redis:tomcatRun

您现在应该能够访问 [role="bare"][role="bare"]http://localhost:8080/ 中的应用程序。

You should now be able to access the application at [role="bare"]http://localhost:8080/

Exploring the httpsession-xml Sample Application

现在，您可以尝试使用该应用程序了。使用以下信息填写表单：

Now you can try using the application. Fill out the form with the following information:

  • Attribute Name: username

  • Attribute Value: rob

然后，请点击 Set Attribute 按钮。您现在应该可以看到表中显示的值了。

Now click the Set Attribute button. You should now see the values displayed in the table.

How Does It Work?

我们与 HttpSession 中显示的标准 SessionServlet 进行交互，这在下表中有所说明：

We interact with the standard HttpSession in the SessionServlet shown in the following listing:

src/main/java/sample/SessionServlet.java
Unresolved include directive in modules/ROOT/pages/guides/xml-redis.adoc - include::example$spring-session-samples/spring-session-sample-xml-redis/src/main/java/sample/SessionServlet.java[]

我们不使用 Tomcat 的 HttpSession，而是将值保存在 Redis 中。Spring Session 在浏览器中创建一个名为 SESSION 的 cookie。该 cookie 包含会话 ID。您可以查看 cookie（使用 Chrome 或 Firefox）。

Instead of using Tomcat’s HttpSession, we persist the values in Redis. Spring Session creates a cookie named SESSION in your browser. That cookie contains the ID of your session. You can view the cookies (with Chrome or Firefox).

您可以使用 redis-cli 删除该会话。例如，在基于 Linux 的系统中，您可以键入以下内容：

You can remove the session using redis-cli. For example, on a Linux based system you can type the following:

	$ redis-cli keys '*' | xargs redis-cli del

Redis 文档包含有关 installing redis-cli 的说明。

The Redis documentation has instructions for installing redis-cli.

或者，您也可以删除显式键。为此，将以下内容输入到您的终端中，并确保使用 SESSION cookie 的值替换 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e：

Alternatively, you can also delete the explicit key. To do so, enter the following into your terminal, being sure to replace 7e8383a4-082c-4ffe-a4bc-c40fd3363c5e with the value of your SESSION cookie:

	$ redis-cli del spring:session:sessions:7e8383a4-082c-4ffe-a4bc-c40fd3363c5e

现在，您可以访问 [role="bare"][role="bare"]http://localhost:8080/ 中的应用程序并看到我们添加的属性不再显示。

Now you can visit the application at [role="bare"]http://localhost:8080/ and see that the attribute we added is no longer displayed.