jsf - 我想在下载记录超过 10000 条且用户能够下载的 excel 时在 jsf 中显示警告消息

Question

我想在 jsf 下载 excel 文件中显示警告消息。

我想在下载记录超过 10000 条且用户能够下载的 excel 时在 jsf 中显示警告消息

Answer 1

It's not possible to send multiple responses to one request. You can send only one response back per request. So, in order to be able to send a warning message and a file for download, the client basically needs to send 2 requests.

Easiest would be if the first requests checks the size of the file and then sets the message accordingly.

public void submit() {
    excelFile = prepareExcelFile();

    if (excelFile.getRecordCount() > 10000) {
        addGlobalWarn("It's more than 1000 records! It can take quite some time.");
    }
}

And have the form submit conditionally render a JS window.location call on the exact URL of the excel file.

<h:outputScript rendered="#{not empty bean.excelFile}">
    window.location = '#{excelFile.url}';
</h:outputScript>