Question

我无法获得primeFaces <p:filedownload的工作。我成功使用自定义下载bean下载文件。似乎issu与primefaces文件下载ActionListener有关，但我没有看到如何。有人有线索吗？感谢。

这是我的豆子：

@ManagedBean(name="fileDownloadBean")
@SessionScoped
public class FileDownloadBean implements Serializable {

    private StreamedContent file;

    public StreamedContent getFile() {
        return file;
    }

    public void setFile(StreamedContent file) {
        this.file = file;
    }

    /** Creates a new instance of FileDownloadBean */
    public FileDownloadBean() {
        InputStream stream = this.getClass().getResourceAsStream("sessionlog.csv");
        file = new DefaultStreamedContent(stream, "application/csv", "sessionlog.csv");

    }
}

这是我的观看代码：

<?xml version='1.0' encoding='UTF-8' ?>
<!DOCTYPE composition PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<ui:composition xmlns="http://www.w3.org/1999/xhtml"
                xmlns:ui="http://java.sun.com/jsf/facelets"
                xmlns:h="http://java.sun.com/jsf/html"
                xmlns:p="http://primefaces.prime.com.tr/ui" 
                xmlns:f="http://java.sun.com/jsf/core"
                xmlns:o="http://openfaces.org/"
                template="./../template.xhtml">

    <ui:define name="title">
        #{bundle.Log}
    </ui:define>

    <ui:define name="body">
        <h:form>
            <p:separator style="height: 10px;margin-bottom: 10px;margin-top: 0px;"/>
            <p:commandButton value="#{bundle.Log}" image="ui-icon ui-icon-link" ajax="false" disabled="false">
                <p:fileDownload value="#{fileDownloadBean.file}" />
            </p:commandButton>
</ui:composition>

我收到500错误：NullPointerException：

HTTP Status 500 -

type Exception report

message

descriptionThe server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException
root cause

java.lang.NullPointerException
note The full stack traces of the exception and its root causes are available in the GlassFish Server Open Source Edition 3.1 logs.

GlassFish Server Open Source Edition 3.1

LOG：

WARNING: StandardWrapperValve[Faces Servlet]: PWC1406: Servlet.service() for servlet Faces Servlet threw exception
java.lang.NullPointerException
    at org.primefaces.component.filedownload.FileDownloadActionListener.processAction(FileDownloadActionListener.java:59)
    at javax.faces.event.ActionEvent.processListener(ActionEvent.java:88)
    at javax.faces.component.UIComponentBase.broadcast(UIComponentBase.java:769)
    at javax.faces.component.UICommand.broadcast(UICommand.java:300)
    at javax.faces.component.UIViewRoot.broadcastEvents(UIViewRoot.java:794)
    at javax.faces.component.UIViewRoot.processApplication(UIViewRoot.java:1259)
    at com.sun.faces.lifecycle.InvokeApplicationPhase.execute(InvokeApplicationPhase.java:81)
    at com.sun.faces.lifecycle.Phase.doPhase(Phase.java:101)
    at com.sun.faces.lifecycle.LifecycleImpl.execute(LifecycleImpl.java:118)
    at javax.faces.webapp.FacesServlet.service(FacesServlet.java:409)
    at org.apache.catalina.core.StandardWrapper.service(StandardWrapper.java:1534)
    at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:281)
    at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:175)
    at org.apache.catalina.core.StandardPipeline.doInvoke(StandardPipeline.java:655)
    at org.apache.catalina.core.StandardPipeline.invoke(StandardPipeline.java:595)
    at com.sun.enterprise.web.WebPipeline.invoke(WebPipeline.java:98)
    at com.sun.enterprise.web.PESessionLockingStandardPipeline.invoke(PESessionLockingStandardPipeline.java:91)
    at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:162)
    at org.apache.catalina.connector.CoyoteAdapter.doService(CoyoteAdapter.java:326)
    at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:227)
    at com.sun.enterprise.v3.services.impl.ContainerMapper.service(ContainerMapper.java:170)
    at com.sun.grizzly.http.ProcessorTask.invokeAdapter(ProcessorTask.java:822)
    at com.sun.grizzly.http.ProcessorTask.doProcess(ProcessorTask.java:719)
    at com.sun.grizzly.http.ProcessorTask.process(ProcessorTask.java:1013)
    at com.sun.grizzly.http.DefaultProtocolFilter.execute(DefaultProtocolFilter.java:225)
    at com.sun.grizzly.DefaultProtocolChain.executeProtocolFilter(DefaultProtocolChain.java:137)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:104)
    at com.sun.grizzly.DefaultProtocolChain.execute(DefaultProtocolChain.java:90)
    at com.sun.grizzly.http.HttpProtocolChain.execute(HttpProtocolChain.java:79)
    at com.sun.grizzly.ProtocolChainContextTask.doCall(ProtocolChainContextTask.java:54)
    at com.sun.grizzly.SelectionKeyContextTask.call(SelectionKeyContextTask.java:59)
    at com.sun.grizzly.ContextTask.run(ContextTask.java:71)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.doWork(AbstractThreadPool.java:532)
    at com.sun.grizzly.util.AbstractThreadPool$Worker.run(AbstractThreadPool.java:513)
    at java.lang.Thread.run(Thread.java:662)

Answer 1

InputStream stream = this.getClass().getResourceAsStream("sessionlog.csv");

您找到CSV文件的方式希望它与当前类FileDownloadBean一起位于相同的包中。

如果它实际上位于包根目录中，那么您应该使用：

InputStream stream = this.getClass().getResourceAsStream("/sessionlog.csv");

或者如果它实际上位于不同的包中，例如com.example，那么您应该使用：

InputStream stream = this.getClass().getResourceAsStream("/com/example/sessionlog.csv");

或者如果它实际上位于公共webcontent的根目录中（/WEB-INF文件夹也位于所有其他Web文件中），那么您应该使用：

InputStream stream = externalContext.getResourceAsStream("/sessionlog.csv");

（顺便说一句，它也适用于WAR类而不是this.getClass()）

Answer 2

我修改了我的InputStream代码

InputStream stream = this.getClass().getResourceAsStream("sessionlog.csv");

改变

InputStream stream = new FileInputStream(new File("URL"))

这是解决方案。

Answer 3

您确定已成功将CSV文件作为资源从Class中加载吗？看起来InputStream可能为null。

Answer 4

我的fileuplaad.xhtml如下所示

  <html xmlns="http://www.w3.org/1999/xhtml"
    xmlns:h="http://java.sun.com/jsf/html"
    xmlns:f="http://java.sun.com/jsf/core"
    xmlns:ui="http://java.sun.com/jsf/facelets"
    xmlns:p="http://primefaces.org/ui">


    <h:form id="downloadFileForm">
            <p:commandButton id="downloadLink" value="Download"                                                                             ajax="false"
                                                onclick="PrimeFaces.monitorDownload(start, stop)"
                                                icon="ui-icon-arrowthichk-s">
                                                <p:fileDownload value="#{fileDownloadController.file}" />
                                            </p:commandButton>


        </h:form>
    </html>

Here is my bean:
@ManagedBean(name="fileDownloadController")
public class FileDownloadController implements Serializable {


    private static final long serialVersionUID = 1L;

    private StreamedContent file;  


    public FileDownloadController() {          
        InputStream stream = ((ServletContext)FacesContext.getCurrentInstance().getExternalContext().getContext()).getResourceAsStream("/download/FileName.csv");  
        file = new DefaultStreamedContent(stream, "download/csv", "FileName.csv");  
    }  

    public StreamedContent getFile() {  
        return file;  
    }    
}

PrimeFaces fileDownload不起作用

4 个答案: