如何使用PrimeFaces在UI上可视化图片

Question

我想制作一个可切换的表单，其中来自我列表的每个代理机构将位于不同的可切换面板中，其中将包含照片+其他信息。可切换式面板可以很好地工我成功地从数据库中获取代理并打印他们的名字，但我在用户界面上显示他们的图片时遇到问题。

这里是我的.xhtml页面形式：

<h:form> 
    <p:growl id="growl" showDetail="true" /> 

      <c:forEach items="#{agencyBean.agencyList}" var="inputBoxes"> 

     <p:fieldset legend="${inputBoxes.tUser.name}" toggleable="true" 
       toggleSpeed="500"> 
       <p:ajax event="toggle" listener="#{fieldsetBean.handleToggle}" update="growl"/> 

       <h:panelGrid columns="2" cellpadding="10"> 
        <p:graphicImage value="#{agencyBean.getAgencyPhoto(inputBoxes)}" /> 
        Agency Name: <h:outputText value="${inputBoxes.tUser.name}"/> 
        Agency Phone:<h:outputText value="${inputBoxes.tUser.phone}"/> 
       </h:panelGrid> 
      </p:fieldset>  
     </c:forEach> 
    </h:form> 

这里是我的bean类：

@ManagedBean(name = "agencyBean") 
@ViewScoped 
public class AgencyBean implements Serializable{ 
    private TAgency tAgency = new TAgency(); // + get and set method 
    private List<TAgency> agencyList; // + get and set method 

    @PostConstruct 
    public void init() { 
     EntityManager em = HibernateUtil.getEntityManager(); 
     Query q = em.createQuery("select u from TAgency u"); 
     agencyList = q.getResultList(); 
    } 

    public StreamedContent getAgencyPhoto(TAgency agency) { 
     FacesContext context = FacesContext.getCurrentInstance(); 

     if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) { 
      return new DefaultStreamedContent(); 
     } else { 
      if (agency.gettUser().getPhoto() == null) { 
       return new DefaultStreamedContent(); 
      } else { 
       return new DefaultStreamedContent(new ByteArrayInputStream(
         (agency.gettUser().getPhoto()))); 
      } 
     } 
    } 
} 

它给了我在Eclipse控制台中的错误是：

SEVERE: Servlet.service() for servlet [Faces Servlet] in context with path [/MasterThesis] threw exception 
java.io.IOException: java.lang.NullPointerException 
    at org.primefaces.application.PrimeResourceHandler.handleResourceRequest(PrimeResourceHandler.java:122) 
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:643) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:304) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at bg.fmi.master.thesis.util.CharacterEncodingFilter.doFilter(CharacterEncodingFilter.java:20) 
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:243) 
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210) 
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240) 
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:164) 
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:462) 
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164) 
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100) 
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:562) 
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118) 
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:395) 
    at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:250) 
    at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188) 
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:302) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886) 
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908) 
    at java.lang.Thread.run(Thread.java:662) 
Caused by: java.lang.NullPointerException 
    at com.sun.faces.mgbean.BeanManager$ScopeManager$ViewScopeHandler.getFromScope(BeanManager.java:566) 
    at com.sun.faces.mgbean.BeanManager$ScopeManager.getFromScope(BeanManager.java:477) 
    at com.sun.faces.mgbean.BeanManager.getBeanFromScope(BeanManager.java:240) 
    at com.sun.faces.el.ManagedBeanELResolver.resolveBean(ManagedBeanELResolver.java:242) 
    at com.sun.faces.el.ManagedBeanELResolver.getValue(ManagedBeanELResolver.java:116) 
    at com.sun.faces.el.DemuxCompositeELResolver._getValue(DemuxCompositeELResolver.java:176) 
    at com.sun.faces.el.DemuxCompositeELResolver.getValue(DemuxCompositeELResolver.java:203) 
    at org.apache.el.parser.AstIdentifier.getValue(AstIdentifier.java:71) 
    at org.apache.el.parser.AstValue.getValue(AstValue.java:147) 
    at org.apache.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:189) 
    at org.primefaces.application.PrimeResourceHandler.handleResourceRequest(PrimeResourceHandler.java:85) 
    ... 20 more 

Answer 1

我改变了一点点我的代码，它现在的作品：

<p:graphicImage value="#{agencyBean.agencyPhoto}"> 
         <f:param name="agencyId" value="#{agency.tUser.id}" /> 
        </p:graphicImage> 

豆：

public StreamedContent getAgencyPhoto() throws IOException { 
     FacesContext context = FacesContext.getCurrentInstance(); 

     if (context.getCurrentPhaseId() == PhaseId.RENDER_RESPONSE) { 
      return new DefaultStreamedContent(); 
     } else { 
      String agencyId = context.getExternalContext() 
        .getRequestParameterMap().get("agencyId"); 
      TAgency currentAgency = new TAgency(); 
      for (TAgency currAgency : agencyList) { 
       if (currAgency.gettUserId() == Long.valueOf(agencyId)) 
        currentAgency = currAgency; 

      } 
      byte[] image = (byte[]) currentAgency.gettUser().getPhoto(); 
      if (image == null) { 
       return new DefaultStreamedContent(); 
      } else { 
       return new DefaultStreamedContent(new ByteArrayInputStream(
         image)); 
      } 
     } 
    }