Question

我试图让用户将我的servlet中的数据保存为CSV文件。最初我只是找到他们的桌面来删除文件，但是这条路线的许可将被拒绝，所以我想问用户他们想要保存它的位置。

从我所看到的，我不能在servlet中使用Swing API，因为Tomcat不知道如何绘制GUI。我试过这段代码：

    String fileName = "ClassMonitor" + formatter.format(currentDate) + ".csv";

    File csvFile = new File(fileName);

    //Attempt to write as a CSV file 
    try{

        JFileChooser fileChooser = new JFileChooser();
        fileChooser.setSelectedFile(csvFile);
        int returnValue = fileChooser.showSaveDialog(null);

        if(returnValue == JFileChooser.APPROVE_OPTION)
        {
            BufferedWriter out = new BufferedWriter(new FileWriter(csvFile));

            //Iterates and writes to file
            for(ClassInfo classes : csvWrite)
            {
                //Check if the class has a comma. Currently, only section titles have a comma in them, so that's all we check for.
                classes.setSectionTitle(replaceComma(classes.getSectionTitle()));

                out.write(classes.toString());
            }

            //Close the connection
            out.close();
        }

        //Log the process as successful.
        logger.info("File was successfully written as a CSV file to the desktop at " + new Date() + "\nFilename" +
                "stored as " + fileName + ".");

    }
    catch(FileNotFoundException ex)
    {
        //Note the exception
        logger.error("ERROR: I/O exception has occurred when an attempt was made to write results as a CSV file at " + new Date());
    }
    catch(IOException ex)
    {
        //Note the exception
        logger.error("ERROR: Permission was denied to desktop. FileNotFoundException thrown.");
    }
    catch(Exception ex)
    {
        //Note the exception
        logger.error("ERROR: Save file was not successfull. Ex: " + ex.getMessage());
    }



}

但这会抛出一个无头的异常。

有关如何在servlet中实现类似保存文件对话框的任何指导将不胜感激。

Answer 1

只需将其写入响应正文而不是本地（!!）磁盘文件系统。

response.setContentType("text/csv"); // Tell browser what content type the response body represents, so that it can associate it with e.g. MS Excel, if necessary.
response.setHeader("Content-Disposition", "attachment; filename=name.csv"); // Force "Save As" dialogue.
response.getWriter().write(csvAsString); // Write CSV file to response. This will be saved in the location specified by the user.

Content-Disposition: attachment标题会处理另存为魔法。

另见：

JSP generating Excel spreadsheet (XLS) to download

Answer 2

您无法从servlet调用JFileChooser，因为servlet在服务器上运行，而不是在客户端上运行;所有Java代码都在服务器上执行。如果要将文件保存在服务器上，则需要知道要写入的路径。

如果要提示用户的浏览器保存文件，请使用内容处置标题：Uses of content-disposition in an HTTP response header

如何使用servlet中的保存文件对话框？

2 个答案:

另见：