导出到 Excel JSF 和 PrimeFaces

java apache-poi jsf-2 primefaces tomcat7

2022-09-03 00:48:48

使用 JDK 1.6、JSF 2.1、PrimeFaces 2.2.1、POI 3.2 和 Apache Tomcat 7

我正在尝试设置一个servlet，以允许根据用户选择下载excel文件。Excel 文档是在运行时创建的。

没有错误，代码确实进入了servlet。

我点击按钮，没有任何反应。我没有使用PrimeFaces使用的数据表导出，因为我需要对Excel文档中的数据进行重新排序和自定义格式设置。

ExportExcelReports.java

protected void processRequest(HttpServletRequest request, HttpServletResponse response)
        throws ServletException, IOException {       
    response.setContentType("application/vnd.ms-excel");
    response.setHeader("Content-Disposition", "attachment; filename=\"my.xls\"");                

    HSSFWorkbook workbook = new HSSFWorkbook();

    HSSFSheet sheet = workbook.createSheet();
    HSSFRow row = sheet.createRow(0);
    HSSFCell cell = row.createCell(0);
    cell.setCellValue(0.0);

    FileOutputStream out = new FileOutputStream("my.xls");
    workbook.write(out);
    out.close();
}

ProjectReportBean.java

public void getReportData() {
    try {
        FacesContext ctx = FacesContext.getCurrentInstance();
        ExternalContext ectx = ctx.getExternalContext();
        HttpServletRequest request = (HttpServletRequest) ectx.getRequest();
        HttpServletResponse response = (HttpServletResponse) ectx.getResponse();
        RequestDispatcher dispatcher = request.getRequestDispatcher("/ExportExcelReports");
        dispatcher.forward(request, response);
        ctx.responseComplete();
    } catch (Exception e) {}
}

索引.xhtml

<h:form id="reportsForm">
    <h:outputLabel for="report" value="Reports" /><br />
    <h:selectOneMenu id="report" value="#{projectReportBean.selectedReport}" required="true" requiredMessage="Select Report">
        <f:selectItem itemLabel="---" noSelectionOption="true" />
        <f:selectItems value="#{projectReportBean.reports}" />
    </h:selectOneMenu>

    <p:commandButton action="#{projectReportBean.getReportData}" value="Export" update="revgrid" />                      
</h:form>

答案 1

有两个问题。

第一个问题是默认情况下发送 Ajax 请求。此请求由 JavaScript 代码触发。但是，JavaScript 无法对包含文件下载的响应执行任何操作。由于安全限制，JavaScript无法生成“另存为”对话框或其他内容。响应基本上被完全忽略了。<p:commandButton>

您需要添加以关闭ajax，以便按钮触发正常的同步HTTP请求，或者您需要将其替换为标准。ajax="false"<p:commandButton><h:commandButton>

<p:commandButton ajax="false" ... />

或

<h:commandButton ... />

第二个问题是，你的 servlet 根本不会将 Excel 文件写入响应，而是写入存储在服务器工作目录中的本地文件。基本上，HTTP 响应不包含任何内容。您需要传递给该方法。HttpServletResponse#getOutputStream()WorkBook#write()

workbook.write(response.getOutputStream());

在不相关的说明中，我想知道servlet在这里有什么用处。你想在JSF之外重用它吗？如果没有，你根本不需要调度到 servlet，而只需在 bean 的 action 方法中执行相同的代码。那个空的块也不好。我只是将其声明为方法，或者至少将其重新命名为.catchthrowsnew FacesException(e)

根据评论进行更新，您似乎对servlet根本不感兴趣。下面是对如何在 JSF 操作方法中以编程方式发送 Excel 文件的次要重写。

public void getReportData() throws IOException {
    HSSFWorkbook workbook = new HSSFWorkbook();
    HSSFSheet sheet = workbook.createSheet();
    HSSFRow row = sheet.createRow(0);
    HSSFCell cell = row.createCell(0);
    cell.setCellValue(0.0);

    FacesContext facesContext = FacesContext.getCurrentInstance();
    ExternalContext externalContext = facesContext.getExternalContext();
    externalContext.setResponseContentType("application/vnd.ms-excel");
    externalContext.setResponseHeader("Content-Disposition", "attachment; filename=\"my.xls\"");

    workbook.write(externalContext.getResponseOutputStream());
    facesContext.responseComplete();
}

答案 2

这是我之前写的和工作案例;

xhtml ;

<h:panelGrid id="viewCommand" style="float:right;" >
                        <p:commandButton value="Export Excel" icon="ui-icon-document"
                            ajax="false" actionListener="#{xxx.export2Excel}"
                            rendered="#{xxx.showTable}">
                            <p:fileDownload value="#{xxx.exportFile}"
                                contentDisposition="attachment" />
                        </p:commandButton></h:panelGrid>

Java side（with POI） ;

protected void lOBExport2Excel(List table) throws Throwable {
    Row row = null;
    Cell cell = null;
    try {

        Workbook wb = new HSSFWorkbook();
        HSSFCellStyle styleHeader = (HSSFCellStyle) wb.createCellStyle();
        HSSFFont fontHeader = (HSSFFont) wb.createFont();
        fontHeader.setBoldweight(HSSFFont.BOLDWEIGHT_BOLD);
        styleHeader.setFont(fontHeader);
        Sheet sheet = wb.createSheet("sheet");
        row = sheet.createRow((short) 0);

        for (int i = 0; i < columnNames.size(); i++) {
            cell = row.createCell(i);
            cell.setCellValue(columnNames.get(i));
            cell.setCellStyle(styleHeader);
        }

        int j = 1;

        for (DBData[] temp : tabularData) {
            row = sheet.createRow((short) j);
            for (int k = 0; k < temp.length; k++) {
                HSSFCellStyle styleRow = (HSSFCellStyle) wb.createCellStyle();
                HSSFFont fontRow = (HSSFFont) wb.createFont();
                fontRow.setBoldweight(HSSFFont.BOLDWEIGHT_NORMAL);
                styleRow.setFont(fontRow);
                cell = row.createCell(k);
                setStyleFormat(temp[k].getDataType(), styleRow, wb);
                cell.setCellValue(temp[k].toFullString());
                cell.setCellStyle(styleRow);
            }

            j++;
        }

        String excelFileName = getFileName("xls");

        FileOutputStream fos = new FileOutputStream(excelFileName);
        wb.write(fos);
        fos.flush();
        fos.close();

        InputStream stream = new BufferedInputStream(new FileInputStream(excelFileName));
        exportFile = new DefaultStreamedContent(stream, "application/xls", excelFileName);


    } catch (Exception e) {
        catchError(e);
    }

}