Velocity-Tools in Spring 3 app - Linktool causes NPE, how to solve?

I'm using a modified VelocityToolboxView (found somwhere here on stackoverflow) to make use of the Velocity-Tools 2.0 in spring 3. It looks like it is configuring well, but when I call the $link tool in a .vm file I get an NPE. Scanning through the Velocity-Tools sources I found that it tries to configure the tool with request and response from the ValueParser props, but they are null 开发者_高级运维here.

Here the stack:

LinkTool.configure(ValueParser) line: 100   
LinkTool(SafeConfig).configure(Map) line: 113   
NativeMethodAccessorImpl.invoke0(Method, Object, Object[]) line: not available [native method]  
NativeMethodAccessorImpl.invoke(Object, Object[]) line: 39  
DelegatingMethodAccessorImpl.invoke(Object, Object[]) line: 25  
Method.invoke(Object, Object...) line: 597  
ToolInfo.invoke(Method, Object, Object) line: 363   
ToolInfo.configure(Object, Map<String,Object>) line: 294    
ToolInfo.create(Map<String,Object>) line: 255   
Toolbox.getFromInfo(String, String, Map<String,Object>) line: 152   
Toolbox.get(String, String, Map<String,Object>) line: 112   
ToolContext.findTool(String) line: 221  
ToolContext.get(String) line: 206   
VelocityContext(AbstractContext).get(String) line: 197  

When the ValueParser needs to have the request/response values in its map at this time, where is this normally injected and by whom?

Here is the view class I use:

public class VelocityToolsView extends VelocityToolboxView
{

  private static ToolContext toolContext;

  @Override
  protected Context createVelocityContext(@SuppressWarnings("rawtypes") Map model,
      HttpServletRequest request, HttpServletResponse response) throws IOException
  {
    VelocityContext context = new VelocityContext(getToolContext());
    if (model != null)
    {
      @SuppressWarnings("unchecked")
      Set<Map.Entry<String, Object>> entrySet = model.entrySet();
      for (Map.Entry<String, Object> entry : entrySet)
      {
        context.put(entry.getKey(), entry.getValue());
      }
    }
    return context;
  }

  private ToolContext getToolContext() throws IllegalStateException, IOException
  {
    if (toolContext == null)
    {
      XmlFactoryConfiguration factoryConfiguration = new XmlFactoryConfiguration("Default Tools");
      factoryConfiguration.read(getServletContext()
          .getResourceAsStream(getToolboxConfigLocation()));
      ToolManager toolManager = new ToolManager();
      toolManager.configure(factoryConfiguration);
      toolContext = toolManager.createContext();
    }
    return toolContext;
  }

VelocityToolbox is something from ancient times that was deprecated 5 years ago. I am using this technique to integrate Tools into Spring.

I was finding this problem too and eventually solved it using this variation on @serg's technique.