GWT:将PDF文档从服务器发送到客户端

我有一个RPC服务，其中一个方法是使用Pentaho报告引擎生成报告。报告是一个PDF文件。我想做的是，当用户请求一份报告时，该报告将被发送回他，并弹出保存对话框或其他内容。我在我的服务方法中尝试了以下内容：

Resource res = manager.createDirectly(new URL(reportUrl), MasterReport.class);
            MasterReport report = (MasterReport) res.getResource();
            report.getParameterValues().put("journalName", "FooBar");
            this.getThreadLocalResponse().setContentType("application/pdf");
            PdfReportUtil.createPDF(report, this.getThreadLocalResponse().getOutputStream());

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但它不起作用。怎么做呢？

我做的有点不同。我有一个单独的servlet，用于生成PDF。在客户端上，执行以下操作：

Cookies.setCookie(set what ever stuff PDF needs...);
Window.open(GWT.getModuleBaseURL() + "DownloadPDF", "", "");

servlet DownloadPDF的外观如下所示：

public class DownloadPDF extends HttpServlet {

public void doGet(HttpServletRequest request, HttpServletResponse response) {
    Cookie[] cookies = request.getCookies();
    try {
        // get cookies, generate PDF.
        // If PDF is generated to to temp file, read it
        byte[] bytes = getFile(name);
     sendPDF(response, bytes, name);
    } catch (Exception ex) {
        // do something here
    }
}

byte[] getFile(String filename) {

    byte[] bytes = null;

    try {
        java.io.File file = new java.io.File(filename);
        FileInputStream fis = new FileInputStream(file);
        bytes = new byte[(int) file.length()];
        fis.read(bytes);
    } catch (Exception e) {
        e.printStackTrace();
    }

    return bytes;
}

void sendPDF(HttpServletResponse response, byte[] bytes, String name) throws IOException {
    ServletOutputStream stream = null;

    stream = response.getOutputStream();
    response.setContentType("application/pdf");
    response.addHeader("Content-Type", "application/pdf");
    response.addHeader("Content-Disposition", "inline; filename=" + name);
    response.setContentLength((int) bytes.length);
    stream.write(bytes);
    stream.close();
}
}

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@BJB在GWT客户端中获取字节如何将字节写入文件，GWT不支持，对吗？