关于Spring Portlet开发中的HandlerInterceptor

关于Spring Portlet开发中的HandlerInterceptor

在Spring Portlet开发中，我们可以用HandlerInterceptor 来实现对于portlet的拦截，主要的需求场景比如授权处理。它可以让我们来自定义处理器执行链。

其实很类似Web开发中的Filter,但是不同的在于Filter是Servlet范畴的概念，它可以用来操作ServletRequest 和ServletResponse，并且配置在web.xml中，而Portlet HandlerInterceptor是Portlet范畴的概念，它可以用来操作PortletRequest和PortletResponse，并且配置在Spring应用上下文中。

在HandlerInterceptor中定义了若干主要方法：具体参见

为了让我们的应用使用HandlerInterceptor，一个常见的设计模式是使用Adaptor模式，让我们的自定义HandlerInterceptor类继承自HandlerInterceptorAdaptor类，然后进行覆写。 下面是个例子.

例子：

a.需求，我们需要在Portlet的任何页面上都可以用到当前登录的用户的用户名和所属权限，那么我们的可以开发一个HandlerInterceptor:

1. /**
2. *
3. * This handler interceptor will intercept the request before/after the flow.
4. * Since it is configured in envprovisioning-config.xml ,so it will intercept request to envprovision flow
5. * We can have some pre/post handling work such as initialize the variables
6. *@author cwang58
7. *@created date: Feb 5, 2013
8. */
9. publicclass EnvProvisionHandlerInterceptor extends HandlerInterceptorAdapter {
10. privatestaticfinal SimpleLogger LOGGER = new SimpleLogger(EnvProvisionHandlerInterceptor.class);
11. /**
12. * This method will pre handle before rendering the first page in the flow
13. * Here it get the current logined user information from the ThemeDisplay
14. * Then get the role that this user belongs to ,we make sure whether this user belongs to AER Admin-AERAdmin
15. * if user belongs to this ,then set isAdministrator attribute to request scope so that it can be used in every page of this flow.
16. */
17. @Override
18. publicboolean preHandleRender(RenderRequest request,
19. RenderResponse response, Object handler) {
20. User user = EnvProUtil.getUserObj(request);
21. if(user == null){
22. returnfalse;
23. }
24. String userName= user.getScreenName();
25. LOGGER.debug("Login user name:"+userName);
26. boolean isAdministrator = false;
27. try{
28. List<Role> roles = user.getRoles();
29. for(int i= 0;i<roles.size();i++) {
30. Role role =roles.get(i);
31. if("AER Admin-AERAdmin".equals(role.getName()) || "Administrator".equals(role.getName())){
32. isAdministrator=true;
33. LOGGER.debug("Login user has role:"+role.getName());
34. break;
35. }
36. }
37. request.setAttribute("userId", userName);
38. request.setAttribute("isAdministrator", isAdministrator);
39. returntrue;
40. }catch(SystemException ex){
41. LOGGER.error("SystemException occurs when get current user role",ex);
42. returnfalse;
43. }
44. }
45. }

比如以上的例子中，我们从ThemeDisplay中获取当前用户的权限和用户名，然后把它设置到RenderRequest的request scope上。