使用 Struts 2 的外部 servlet

【问题标题】：External servlet with Struts 2使用 Struts 2 的外部 servlet
【发布时间】：2014-09-05 16:10:39
【问题描述】：

如何在我的项目中使用外部 servlet 与 Struts2、Hibernate、Spring Security 因为我必须用 JS 显示一些图表和饼图。

问题在于我的会话工厂，我不知道如何在我的 servlet 中调用它 当我打电话给我的沙发 DAO 时，它给了我

java.lang.NullPointerException
at com.charting.PieChartServlet.doPost(PieChartServlet.java:70)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
    at org.apache.struts2.dispatcher.ng.filter.StrutsExecuteFilter.doFilter(StrutsExecuteFilter.java:90)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:96)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareFilter.doFilter(StrutsPrepareFilter.java:91)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:91)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:125)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:211)
    at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
    at org.mortbay.jetty.Server.handle(Server.java:313)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
    at org.mortbay.jetty.HttpConnection$RequestHandler.headerComplete(HttpConnection.java:830)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:514)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)
    at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)

PieChartServlet:

@Controller
public class PieChartServlet extends HttpServlet {
    private static final long serialVersionUID = 1L;    
    @Autowired
    private CheckAction checkAction;
    private CheckManager checkManager
    private Check check;
    private JFreeChart chart;

    public PieChartServlet() {

    }

    @Override
    public void init() throws ServletException {

        checkAction = new CheckAction();
    }


    public void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        String uri = request.getRequestURI();
        int i = uri.lastIndexOf('/') + 1;
        int j = uri.lastIndexOf('.');
        String key = uri.substring(i, j);
        String view = "/error.jsp";
        String fc= request.getParameter("fc");
        System.out.println(request.getParameter("fc") +"**********************");
        check= checkManager.listerCheck(fc);
        if (key.equals("AfficherPie")) {



             DefaultPieDataset donnees=new DefaultPieDataset();
             donnees.setValue("OK",19);
             donnees.setValue("Not Ok",5);
             donnees.setValue("NA",5);
             donnees.setValue("NR",5);
                // créer le graphique
             chart = ChartFactory.createPieChart3D(
                         "Reporting  ",  //titre
                          donnees,                // données à afficher
                          true,                   // afficher la légende
                          true,
                          true
                      );

NumberFormat.getNumberInstance(), NumberFormat.getPercentInstance()));
                final PiePlot plot = (PiePlot) chart.getPlot();
                plot.setBackgroundPaint(Color.white);
                plot.setCircular(true);
                plot.setLabelGenerator(new StandardPieSectionLabelGenerator(
                    "{0} = {2}", NumberFormat.getNumberInstance(), NumberFormat.getPercentInstance()
                ));
                plot.setNoDataMessage("No data available");
                plot.setDrawingSupplier(new ChartDrawingSupplier());
                chart.setBorderVisible(true);



                if (chart != null) {
                    int width = 600;
                    int height = 400;
                    response.setContentType("image/jpeg");
                    //response.flushBuffer();

                    OutputStream out = response.getOutputStream();
                    ChartUtilities.writeChartAsJPEG(out, chart, width, height);
                }

        } 

        request.getRequestDispatcher(view).forward(request, response);
    }
    public void doPost(HttpServletRequest request,HttpServletResponse response) throws ServletException, IOException {
        doGet(request, response);
    }

}

java.lang.NullPointerException 在check= checkManager.listerCheck(fc); 中，即使参数不为空，我已经使用此方法没有任何问题

堆栈跟踪：

java.lang.NullPointerException
    at 
    com.ji.checkImpl.CheckDaoImpl.listerCheck(CheckDaoImpl.java:63)
    at com.ji.checkImpl.CheckManagerImpl.listerCheck(CheckManagerImpl.java:52)
    at com.ji.PieChartServlet.doGet(PieChartServlet.java:78)
    at com.ji.PieChartServlet.doPost(PieChartServlet.java:125)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:727)
    at javax.servlet.http.HttpServlet.service(HttpServlet.java:820)
    at org.mortbay.jetty.servlet.ServletHolder.handle(ServletHolder.java:487)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1093)
    at org.apache.struts2.dispatcher.ng.filter.StrutsExecuteFilter.doFilter(StrutsExecuteFilter.java:72)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareAndExecuteFilter.doFilter(StrutsPrepareAndExecuteFilter.java:86)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.apache.struts2.dispatcher.ng.filter.StrutsPrepareFilter.doFilter(StrutsPrepareFilter.java:91)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118)
    at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:54)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.ui.DefaultLoginPageGeneratingFilter.doFilter(DefaultLoginPageGeneratingFilter.java:91)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:183)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:105)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.session.ConcurrentSessionFilter.doFilter(ConcurrentSessionFilter.java:125)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87)
    at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342)
    at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192)
    at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160)
    at org.springframework.web.filter.DelegatingFilterProxy.invokeDelegate(DelegatingFilterProxy.java:237)
    at org.springframework.web.filter.DelegatingFilterProxy.doFilter(DelegatingFilterProxy.java:167)
    at org.mortbay.jetty.servlet.ServletHandler$CachedChain.doFilter(ServletHandler.java:1084)
    at org.mortbay.jetty.servlet.ServletHandler.handle(ServletHandler.java:360)
    at org.mortbay.jetty.security.SecurityHandler.handle(SecurityHandler.java:216)
    at org.mortbay.jetty.servlet.SessionHandler.handle(SessionHandler.java:181)
    at org.mortbay.jetty.handler.ContextHandler.handle(ContextHandler.java:712)
    at org.mortbay.jetty.webapp.WebAppContext.handle(WebAppContext.java:405)
    at org.mortbay.jetty.handler.ContextHandlerCollection.handle(ContextHandlerCollection.java:211)
    at org.mortbay.jetty.handler.HandlerCollection.handle(HandlerCollection.java:114)
    at org.mortbay.jetty.handler.HandlerWrapper.handle(HandlerWrapper.java:139)
    at org.mortbay.jetty.Server.handle(Server.java:313)
    at org.mortbay.jetty.HttpConnection.handleRequest(HttpConnection.java:506)
    at org.mortbay.jetty.HttpConnection$RequestHandler.content(HttpConnection.java:844)
    at org.mortbay.jetty.HttpParser.parseNext(HttpParser.java:644)
    at org.mortbay.jetty.HttpParser.parseAvailable(HttpParser.java:211)
    at org.mortbay.jetty.HttpConnection.handle(HttpConnection.java:381)
    at org.mortbay.io.nio.SelectChannelEndPoint.run(SelectChannelEndPoint.java:396)
    at org.mortbay.thread.BoundedThreadPool$PoolThread.run(BoundedThreadPool.java:442)

【问题讨论】：

  • 发布 servlet 的代码，以及如何构建会话工厂。
  • okk @RomanC tnx 寻求帮助

标签： java spring servlets struts2 nullpointerexception


【解决方案1】：

问题在于您的控制器的依赖性，该控制器尚未连接。要连接依赖关系，请确保CheckManager 是一个spring bean，即如果您使用基于注释的配置或在spring xml 配置中使用bean 标记，则具有一些@Component 注释。然后在属性上加上@Autowired注解。 

@Autowired
private CheckManager checkManager;
public setCheckManager(CheckManager checkManager){
  this.checkManager = checkManager;
}

要将 servlet 与 Struts 2 框架分开使用，您应该使用 struts.xml 中的配置设置将 servlet 从过滤器映射中排除。

<constant name="struts.action.excludePattern" value="/piechart/?.*"/>

web.xml中的servlet映射：

<servlet>
  <servlet-name>piechart</servlet-name>
  <servlet-class>com.charting.PieChartServlet</servlet-class>
</servlet>
<servlet-mapping>
  <servlet-name>piechart</servlet-name>
  <url-pattern>/piechart/*</url-pattern>
</servlet-mapping>

【讨论】：

  • 它不起作用......但是请我如何在 servlet 中调用 SessionFactory 我认为 Spring Security 有问题？？
  • 会话工厂可以像检查管理器一样自动装配。
  • 我也有同样的问题 nullPointer .!
  • 发布堆栈跟踪，或者您可以通过引用这个发布另一个问题并解释它的不同之处。
  • ahhh DAO 中的 Null Pointeur 指的是这一行 Criteria criteria =session.getCurrentSession().createCriteria(Check.class);
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