velocity模板引擎学习(2)-velocity tools 2.0

使用velocity后，原来的很多标签无法使用了，必须借助velocity tools来完成，目前velocity tools最新版本是2.0，下面是velocity tools的一些注意事项：

1. 与Spring MVC 3.x/4.x的集成问题

Spring 3.x/4.x只支持1.3.x的velocity tools，要使用2.0必须自己扩展VelocityToolboxView类

 1 package org.springframework.web.servlet.view.velocity;
 2 
 3 import java.util.Map;
 4 
 5 import javax.servlet.http.HttpServletRequest;
 6 import javax.servlet.http.HttpServletResponse;
 7 
 8 import org.apache.velocity.context.Context;
 9 import org.apache.velocity.tools.Scope;
10 import org.apache.velocity.tools.ToolManager;
11 import org.apache.velocity.tools.view.ViewToolContext;
12 import org.springframework.web.servlet.view.velocity.VelocityToolboxView;
13 
14 public class VelocityToolbox2View extends VelocityToolboxView {
15     @Override
16     protected Context createVelocityContext(Map<String, Object> model,
17             HttpServletRequest request, HttpServletResponse response)
18             throws Exception {// Create a
19                                 // ChainedContext
20                                 // instance.
21         ViewToolContext ctx;
22 
23         ctx = new ViewToolContext(getVelocityEngine(), request, response,
24                 getServletContext());
25 
26         ctx.putAll(model);
27 
28         if (this.getToolboxConfigLocation() != null) {
29             ToolManager tm = new ToolManager();
30             tm.setVelocityEngine(getVelocityEngine());
31             tm.configure(getServletContext().getRealPath(
32                     getToolboxConfigLocation()));
33             if (tm.getToolboxFactory().hasTools(Scope.REQUEST)) {
34                 ctx.addToolbox(tm.getToolboxFactory().createToolbox(
35                         Scope.REQUEST));
36             }
37             if (tm.getToolboxFactory().hasTools(Scope.APPLICATION)) {
38                 ctx.addToolbox(tm.getToolboxFactory().createToolbox(
39                         Scope.APPLICATION));
40             }
41             if (tm.getToolboxFactory().hasTools(Scope.SESSION)) {
42                 ctx.addToolbox(tm.getToolboxFactory().createToolbox(
43                         Scope.SESSION));
44             }
45         }
46         return ctx;
47     }
48 }
View Code

注：31行tm.configure(getServletContext().getRealPath(getToolboxConfigLocation()));这里，在某些容器，比如weblogic中，getRealPath可能取不到值，可改成

getResource试试

 

然后在spring mvc的servlet配置文件中参考如下设置：

 1 <bean
 2                     class="org.springframework.web.servlet.view.velocity.VelocityViewResolver">
 3                     <property name="order" value="0" />
 4                     <property name="cache" value="true" />
 5                     <property name="prefix" value="" />
 6                     <property name="suffix" value=".vm" />
 7                     <property name="toolboxConfigLocation" value="/WEB-INF/toolbox.xml" />                    
 8                     <property name="contentType" value="text/html;charset=UTF-8" />
 9                     <property name="viewClass" value="org.springframework.web.servlet.view.velocity.VelocityToolbox2View"></property>
10                 </bean>
View Code

 

2. 如何获取当前应用的contextPath

1     <tool>
2         <key>link</key>
3         <scope>request</scope>
4         <class>org.apache.velocity.tools.view.LinkTool</class>
5     </tool>

借助velocity-tools的LinkTool类，在velocity中直接用${link.contextPath}即可得到当前的contextPath

 

3、如何获取url参数

1     <tool>
2         <key>params</key>
3         <scope>request</scope>
4         <class>org.apache.velocity.tools.view.ParameterTool</class>
5     </tool>

然后就可以用类似$params.returnUrl，来获取类似 http://xxx.com/login?returnUrl=abc 中的 abc部分

 

4、如何与Spring-Security集成

1 <sec:authorize access="isAnonymous()">
2 ...
3     </sec:authorize>
View Code

之类的标签无法在velocity中使用，而velocity-tools中也未提供相应的支持，在老外的一篇博客上，看到了解决方案：

 1 package com.cnblogs.yjmyzz.utils;
 2 
 3 import java.util.Collection;
 4 import java.util.HashSet;
 5 import java.util.Set;
 6 import org.springframework.security.core.GrantedAuthority;
 7 import org.springframework.security.core.context.SecurityContextHolder;
 8 import org.springframework.security.core.userdetails.UserDetails;
 9 
10 public class VelocitySecurityUtil {
11 
12     public static String getPrincipal() {
13 
14         Object obj = SecurityContextHolder.getContext().getAuthentication()
15                 .getPrincipal();
16 
17         if (obj instanceof UserDetails) {
18             return ((UserDetails) obj).getUsername();
19         } else {
20             return "anonymous";
21         }
22     }
23 
24     public static boolean isAuthenticated() {
25         return !getPrincipal().equals("anonymous");
26     }
27 
28     public static boolean allGranted(String[] checkForAuths) {
29         Set<String> userAuths = getUserAuthorities();
30         for (String auth : checkForAuths) {
31             if (userAuths.contains(auth))
32                 continue;
33             return false;
34         }
35         return true;
36     }
37 
38     public static boolean anyGranted(String[] checkForAuths) {
39         Set<String> userAuths = getUserAuthorities();
40         for (String auth : checkForAuths) {
41             if (userAuths.contains(auth))
42                 return true;
43         }
44         return false;
45     }
46 
47     public static boolean noneGranted(String[] checkForAuths) {
48         Set<String> userAuths = getUserAuthorities();
49         for (String auth : checkForAuths) {
50             if (userAuths.contains(auth))
51                 return false;
52         }
53         return true;
54     }
55 
56     private static Set<String> getUserAuthorities() {
57         Object obj = SecurityContextHolder.getContext().getAuthentication()
58                 .getPrincipal();
59         Set<String> roles = new HashSet<String>();
60         if (obj instanceof UserDetails) {
61             @SuppressWarnings("unchecked")
62             Collection<GrantedAuthority> gas = (Collection<GrantedAuthority>) ((UserDetails) obj)
63                     .getAuthorities();
64             for (GrantedAuthority ga : gas) {
65                 roles.add(ga.getAuthority());
66             }
67         }
68         return roles;
69     }
70 
71 }
View Code

然后修改配置：

 1     <bean id="velocitySecurityUtil" class="com.cnblogs.yjmyzz.utils.VelocitySecurityUtil" />
 2 
 3     <bean
 4         class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
 5         <property name="order" value="1" />
 6         ...
 7         <property name="viewResolvers">
 8             <list>
 9                 <bean
10                     class="org.springframework.web.servlet.view.velocity.VelocityViewResolver">
11                     <property name="order" value="0" />
12                     ...
13                     <property name="attributesMap">
14                         <map>
15                             <entry key="sec">
16                                 <ref bean="velocitySecurityUtil" />
17                             </entry>
18                         </map>
19                     </property>
20 
21                 </bean>
22                 ...
View Code

页面就能用了：

1     #if(${sec.authenticated}) 
2     ...
3     #end
View Code

注：这个思路也可以用于实现自己的Velocity-Tools类，比如我们创建了一个自己的RequestUtil类

 1 package com.cnblogs.yjmyzz.utils;
 2 import javax.servlet.http.HttpServletRequest;
 3 public class RequestUtil{
 4 
 5     /**
 6      * 获取当前请求的基地址（例如：http://localhost:8080/ctas/xxx.do 返回 http://localhost:8080/ctas/）
 7      *
 8      * @param request
 9      * @return
10      */
11     public static String getBaseUrl(HttpServletRequest request) {
12         return request.getRequestURL().substring(0,
13                 request.getRequestURL().indexOf(request.getContextPath()) + request.getContextPath().length()) + "/";
14     }
15 
16 }
View Code

然后在配置里，加上

 1     <bean id="requestUtil" class="com.cnblogs.yjmyzz.utils.RequestUtil"/>
 2 
 3     <bean
 4             class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
 5         <property name="order" value="1"/>
 6        ...
 7         <property name="viewResolvers">
 8             <list>
 9                 ...
10                 <bean
11                         class="org.springframework.web.servlet.view.velocity.VelocityViewResolver">
12                     <property name="order" value="0"/>
13                  ...
14                     <property name="viewClass"
15                               value="com.cnblogs.yjmyzz.utils.VelocityToolbox2View"></property>
16                     <property name="attributesMap">
17                         <map>
18                           ...
19                             <entry key="req">
20                                 <ref bean="requestUtil"/>
21                             </entry>
22                         </map>
23                     </property>
24                 </bean>
25               ...
26     </bean>
View Code

 vm页面这样用

1 #*取得页面链接基地址*#
2 #macro(baseHref)${req.getBaseUrl($request)}#end
3 ...
4 <base href="#{baseHref}">
5 ...
6 <script type="text/javascript">
7     var baseHref = "#{baseHref}";
8 </script>
9 ...
View Code

顺便提一句：网上有一堆文章和教程，让你在toolbox.xml中添加类似

1     <tool>
2         <key>req</key>
3         <scope>request</scope>
4         <class>com.cnblogs.yjmyzz.utils.RequestUtil</class>
5     </tool>
View Code

在Spring MVC4 + Velocity Tools2的组合下，然而，这并没有什么用，在Spring MVC4 + Velocity-Tools2下，已经不好使了。

最后，Velocity还允许自定义标签（也有人称为自定义指令），支持开发人员定义自己的标签，比如#YourDirective，详情可参考：

编写自定义的 Velocity 指令 

posted @ 2014-12-27 17:50  菩提树下的杨过  阅读(15630)  评论(2)  编辑  收藏  举报