java 如何在 Velocity 模板中访问 Session 或 Request 对象

How to access Session or Request object in Velocity Template

提问by Ifi

I am trying to access HttpServletRequest in some velocity template but never succeed. I have already tried following flavor of syntax

我试图在某些速度模板中访问 HttpServletRequest 但从未成功。我已经尝试过以下语法风格

Current URL: $req.get("attributes").get("CURRENT_URL")) Result > Current URL: $req.get("attributes").get("CURRENT_URL"))

当前 URL：$req.get("attributes").get("CURRENT_URL")) 结果 > 当前 URL：$req.get("attributes").get("CURRENT_URL"))

Current URL: $request.get("attributes").get("CURRENT_URL")) Result > Current URL: $request.get("attributes").get("CURRENT_URL"))

当前 URL：$request.get("attributes").get("CURRENT_URL")) 结果 > 当前 URL：$request.get("attributes").get("CURRENT_URL"))

Current URL: $request.get("attributes").get("CURRENT_URL")) Result > Current URL: $request.get("attributes").get("CURRENT_URL"))

当前 URL：$request.get("attributes").get("CURRENT_URL")) 结果 > 当前 URL：$request.get("attributes").get("CURRENT_URL"))

Current URL: ${request.get("attributes").get("CURRENT_URL"))} Result > Current URL: ${request.get("attributes").get("CURRENT_URL"))}

当前 URL：${request.get("attributes").get("CURRENT_URL"))} 结果 > 当前 URL：${request.get("attributes").get("CURRENT_URL"))}

Note : Web.xml looks like

注意：Web.xml 看起来像

<!-- Processes application requests -->
<servlet>
    <servlet-name>appServlet</servlet-name>
    <servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
    <init-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/spring/appServlet/servlet-context.xml</param-value>
    </init-param>
    <load-on-startup>1</load-on-startup>
</servlet>

<servlet-mapping>
    <servlet-name>appServlet</servlet-name>
    <url-pattern>/*</url-pattern>
</servlet-mapping>

<!-- Define Velocity template compiler -->
<servlet>
  <servlet-name>velocity</servlet-name>
  <servlet-class>
    org.apache.velocity.tools.view.servlet.VelocityViewServlet
  </servlet-class>

  <!-- 
   Unless you plan to put your toolbox.xml and velocity.properties
   under different folders or give them different names, then these
   two init-params are unnecessary as of VelocityTools 1.3.  The
   VelocityViewServlet will automatically look for these files in
   the following locations.
 -->
  <init-param>
    <param-name>org.apache.velocity.toolbox</param-name>
    <param-value>/WEB-INF/toolbox.xml</param-value>
  </init-param>

  <init-param>
    <param-name>org.apache.velocity.properties</param-name>
    <param-value>/WEB-INF/velocity.properties</param-value>
  </init-param>
</servlet>

<!-- Map *.vm files to Velocity -->
<servlet-mapping>
  <servlet-name>velocity</servlet-name>
  <url-pattern>*.vm</url-pattern>
</servlet-mapping>

回答by Diego Ramos

$request.getParameter("parameterName")

$request.getParameter("参数名")

回答by Nathan Bubna

For VelocityTools, the proper references are $request and $response, not $req and $res

对于 VelocityTools，正确的引用是 $request 和 $response，而不是 $req 和 $res

The methods name is getAttribute, not get. So you can do:

方法名称是 getAttribute，而不是 get。所以你可以这样做：

$request.getAttribute('foo')

$request.getAttribute('foo')

or just $request.foo

或者只是 $request.foo

but not $request.get('foo')

但不是 $request.get('foo')

回答by Evan Haas

You won't have access to the HttpServletRequestby default in your Velocity template; you'll only have access to objects that have been placed in to the Contextfor you. So in the backing Java class, add the info you want into the conext:

HttpServletRequest默认情况下，您将无法访问Velocity 模板中的 ；您只能访问已Context为您放入的对象。因此，在支持 Java 类中，将所需的信息添加到上下文中：

context.put("url", request.getAttribute("CURRENT_URL"));

Then in your Velocity template, you can simply reference $url.

然后在您的 Velocity 模板中，您可以简单地引用$url.

回答by Gary Blake

You'll need to roll your own class based on session to do this properly.

您需要根据会话滚动自己的类才能正确执行此操作。

I hit this problem instantly and am now going to create a session class that i will access via a values property as a List of HashMaps.

我立即遇到了这个问题，现在我将创建一个会话类，我将通过 values 属性作为 HashMap 列表访问该类。

Then all you need to do is assign values once to velocity's context before use.

然后您需要做的就是在使用之前为速度的上下文分配一次值。

context.put("session", MySessionClass.values));

回答by Mike

To get specific parameter:

获取具体参数：

$!request.getParameter('parameterName')

To get entire query string:

获取整个查询字符串：

$!request.getQueryString()

回答by Ego Slayer

Try this

试试这个

$request.getSession().getAttribute('userId')