我正在开发继承的 jsp/java ee 应用程序,我想将 Guice IoC 容器引入我的应用程序。但是,我发现了一些障碍。如果有多个路由到使用不同 url 的单个 servlet,我无法将 web.xml 条目转换为 guice 注册。问题在于初始化参数。
以下是我的 web.xml 中的一些摘录:
这与问题无关,但它是我们如何使用初始化参数的一个很好的例子。基本上,它将系统中具有不同角色的用户映射到适当的页面。
<!-- LIST INTERNSHIPS SERVLET -->
<servlet>
<servlet-name>ListInternships</servlet-name>
<servlet-class>pl.poznan.put.ims.controllers.ListInternships</servlet-class>
<init-param>
<param-name>CoordinatorPage</param-name>
<param-value>WEB-INF/pages/coordinator/listinternships.jsp</param-value>
</init-param>
<init-param>
<param-name>MentorPage</param-name>
<param-value>WEB-INF/pages/mentor/listinternships.jsp</param-value>
</init-param>
<init-param>
<param-name>AdministratorPage</param-name>
<param-value>WEB-INF/pages/administrator/listinternships.jsp</param-value>
</init-param>
<init-param>
<param-name>AllowedRoles</param-name>
<param-value>Coordinator, Mentor, Administrator</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>ListInternships</servlet-name>
<url-pattern>/internships</url-pattern>
</servlet-mapping>
这两个是麻烦的:
<!-- CHANGE PASSWORD SERVLET -->
<servlet>
<servlet-name>ChangePassword</servlet-name>
<servlet-class>myapp.controllers.ContextForwarder</servlet-class>
<init-param>
<param-name>SharedPage</param-name>
<param-value>WEB-INF/pages/shared/password.jsp</param-value>
</init-param>
<init-param>
<param-name>AllowedRoles</param-name>
<param-value>*</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>ChangePassword</servlet-name>
<url-pattern>/changepassword</url-pattern>
</servlet-mapping>
<!-- HELP SERVLET -->
<servlet>
<servlet-name>Help</servlet-name>
<servlet-class>myapp.controllers.ContextForwarder</servlet-class>
<init-param>
<param-name>SharedPage</param-name>
<param-value>WEB-INF/pages/help/help.jsp</param-value>
</init-param>
<init-param>
<param-name>AllowedRoles</param-name>
<param-value>*</param-value>
</init-param>
</servlet>
<servlet-mapping>
<servlet-name>Help</servlet-name>
<url-pattern>/help</url-pattern>
</servlet-mapping>
这是我的小服务程序:
@Singleton
public class ContextForwarder extends HttpServlet {
private static final long serialVersionUID = 1L;
private final IUserDao dao;
@Inject
public ContextForwarder(IUserDao dao) {
this.dao = dao;
}
protected void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//trying to get rid of statics, using Ioc
Validator.checkUserLoggedIn (request);
Validator.checkUserAuthorized(this, request);
User currentUser = UserManager.getCurrentUser(request);
//pick matching page for user
String userViewPage = ServletUtils.getUserURL(this, currentUser, "Page");
try {
dao.openSession();
dao.beginTransaction();
currentUser = UserManager.reloadCurrentUser(request, dao);
ServletUtils.forward(request, response, userViewPage);
dao.commit();
}
catch(ServletException e) {
dao.rollback();
throw e;
}
catch(Exception e) {
dao.rollback();
throw new ServletException(e);
}
finally {
dao.closeSession();
}
}
}
public class ServletUtils {
public static void forward(HttpServletRequest request, HttpServletResponse response, String location)
throws ServletException, IOException {
RequestDispatcher view = request
.getRequestDispatcher( response.encodeRedirectURL(location) );
view.forward(request, response);
}
public static String getUserParameter(GenericServlet servlet, User user, String suffix) {
return servlet.getInitParameter( user.getRoles() + suffix );
}
public static String getUserURL(GenericServlet servlet, User user, String suffix)
throws ResourceNotFoundException {
String URL = getUserParameter(servlet, user, suffix);
if(URL == null) {
URL = servlet.getInitParameter("Shared" + suffix);
if(URL == null)
throw new ResourceNotFoundException(suffix);
}
return URL;
}
public static void redirect(HttpServletRequest request, HttpServletResponse response, String location)
throws ServletException, IOException {
response.sendRedirect( response.encodeRedirectURL(location) );
}
}
当我尝试将其翻译成 guice (然后注册此模块):
public class MyServletModule extends ServletModule
{
@Override
protected void configureServlets() {
configureHelp();
configurePassword();
}
private void configureHelp()
{
Map<String, String> params = new HashMap<String, String>();
params.put("SharedPage", "WEB-INF/pages/shared/help.jsp");
params.put("AllowedRoles", "*");
serve("/help").with(ContextForwarder.class, params);
}
private void configurePassword()
{
Map<String, String> params = new HashMap<String, String>();
params.put("SharedPage", "WEB-INF/pages/shared/password.jsp");
params.put("AllowedRoles", "*");
// it's routing correctly to servlet, but it uses params from first registration,
// so that routing to jsp page is incorrect
serve("/changepassword").with(ContextForwarder.class, params);
}
}
问题是 guice 将 ContextForwarder servlet 创建为具有来自第一个注册方法的 init 参数的单例,然后不管请求 url 它具有来自第一个注册的参数。考虑到当前用户角色,是否有任何其他解决方案可以将用户路由到不同站点?是否可以使用两种不同的配置来配置同一个 servlet 类?