Java 如何使用数据库中的primefaces在datatable中加载动态图像？数据表中未显示的图像

我使用PrimFaces5版本在datatable中显示数据库中的图像，但不幸的是，并没有在列中写入实际的图像“image”，而是我的xhtml文件。 我有一个带有StreamedContent属性的对象列表，我需要在组件中显示它。 我扔了两张脸却没有结果

  <p:dataTable id="dta" value="#{UtilisateurComponent.listUtilisateurs()}"  var="current" rows="15" paginator="true" paginatorPosition="bottom" rowKey="current.iduser">
        <p:column> 
                    <f:facet name="header">
                        <h:outputText value="id User" />
                    </f:facet>
                    <h:outputText value="#{current.iuser}"  />
        </p:column>
        <p:column > 
                    <f:facet name="header">
                        <h:outputText value="Photo" />
                    </f:facet>
                        <p:graphicImage  value="#{UtilisateurComponent.content}" height="100" width="150">
                            <f:param name="id" value="#{current.iduser}" />
                        </p:graphicImage>
        </p:column>
  </p:dataTable>

根据我的堆栈跟踪

Grave: Error in streaming dynamic resource. Error reading 'content' on type $Proxy16
juin 17, 2014 10:56:03 PM org.apache.catalina.core.StandardWrapperValve invoke
Grave: "Servlet.service()" pour la servlet Faces Servlet a généré une exception
java.io.IOException: javax.el.ELException: Error reading 'content' on type $Proxy16
    at org.primefaces.application.PrimeResourceHandler.handleResourceRequest(PrimeResourceHandler.java:122)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:306)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.primefaces.webapp.filter.FileUploadFilter.doFilter(FileUploadFilter.java:98)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.springframework.orm.jpa.support.OpenEntityManagerInViewFilter.doFilterInternal(OpenEntityManagerInViewFilter.java:113)
    at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:76)
    at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241)
    at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122)
    at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:501)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170)
    at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:98)
    at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:950)
    at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:408)
    at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1040)
    at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:607)
    at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:315)
    at java.util.concurrent.ThreadPoolExecutor.runWorker(Unknown Source)
    at java.util.concurrent.ThreadPoolExecutor$Worker.run(Unknown Source)
    at java.lang.Thread.run(Unknown Source)
Caused by: javax.el.ELException: Error reading 'content' on type $Proxy16
    at javax.el.BeanELResolver.getValue(BeanELResolver.java:110)
    at javax.el.CompositeELResolver.getValue(CompositeELResolver.java:67)
    at com.sun.faces.el.FacesCompositeELResolver.getValue(FacesCompositeELResolver.java:71)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:116)
    at com.sun.el.parser.AstValue.getValue(AstValue.java:163)
    at com.sun.el.ValueExpressionImpl.getValue(ValueExpressionImpl.java:219)
    at org.primefaces.application.PrimeResourceHandler.handleResourceRequest(PrimeResourceHandler.java:85)
    ... 27 more
Caused by: java.lang.NullPointerException
    at java.io.ByteArrayInputStream.<init>(Unknown Source)
    at com.gestion.projet.web.jsf.UtilisateurComponentImpl.getContent(UtilisateurComponentImpl.java:119)
    at sun.reflect.GeneratedMethodAccessor38.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

在上面的u为null的行中，问题是您没有将他从数据库中带回来，或者您的imageId没有在bean中接收

你可以这样做

<p:graphicImage  value="#{UtilisateurComponent.getContent(current.iduser)}" height="100" width="150"/>

---

希望这会有所帮助。

问题在于传递的参数，您有一个包含多行的dataTable，然后发送具有相同id的参数。

尝试使用有效的静态字符串作为

imageId

（可能为空）。如果可行，那么尝试使用静态图像ID而不是

{current.iduser}

。这将帮助你缩小问题的范围。我不明白我有什么用

StreamedContent getMyContent()

return new DefaultStreamedContent(new ByteArrayInputStream(u.getPhoto()));

<p:graphicImage  value="#{UtilisateurComponent.getContent(current.iduser)}" height="100" width="150"/>

public StreamedContent getContent(Integer userId){...}