使用JSP创建CSV文件时出错（Tomcat 7 / Java）

Question

I have an JSP-File, which creates a CSV-File.

To tell the server that the file is an CSV-File I added the following code to the JSP:

response.setContentType ("application/csv");
response.setHeader("Content-Disposition", "attachment;filename=test.csv"); 

In the file I simply write the content of the file with an "Writer" object (the out-Variable). Therefore I use the following code to gernerate the file:

out.write("test1;test2;etc");

There are about 16 columns for this csv-file with about 3000 rows.

The Problem I have is that the "Download file"-Dialog does not appear with bigger files. When I only have 128 rows it works and the Browser does show the "Download File"-windows. When I have 129 rows the browser simply opens the file with plain text (with the IE ignoring the line breaks). This happens in every browser I tested (IE 11 and Firefox). I actually have no idea why this happens, though my guess is that it has something to do with the Writer-Object. I already tried to "flush()" the Writer, but this doesn't change anything.

Thanks in advance!

Edit: I did strip down the code to the following. When j is limited to 50 it does work. With is being set to 100, it doesn't. The .jsp is open with href.location or window.open() (it does not seem to make a difference)

<%
    int j = 0;
    int k = 0;

    for (j = 0; j < 100; j++)
    {

        out.write(";");

        for (k = 0; k < 16; k++)
        {
            out.write(j + "TEST");

            if (k != 15)
            {
                out.write(";");
            }
        }

        out.write("\r\n");
    }


    response.setContentType ("application/csv");
    response.setHeader("Content-Disposition", "attachment;filename=test.csv"); 
%>

Answer 1

Change below configurations in your tomcat webapps/manager/WEB-INF/web.xml . we can change this setting , just put 0 on each size limit. the finally configure :

  <multipart-config>
       <!-- 50MB max -->
       <max-file-size>524288000</max-file-size>
        <max-request-size>524288000</max-request-size>
        <file-size-threshold>0</file-size-threshold>
     </multipart-config>

Also check for ,

maxPostSize

The maximum size in bytes of the POST which will be handled by the container FORM URL parameter parsing. The limit can be disabled by setting this attribute to a value less than or equal to 0. If not specified, this attribute is set to 2097152 (2 megabytes) .

Another Limit is:

maxHttpHeaderSize The maximum size of the request and response HTTP header, specified in bytes. If not specified, this attribute is set to 4096 (4 KB) .

You find them in

$TOMCAT_HOME/conf/server.xml

Answer 2

Jsp are great to produce HTML output.

As you want to produce csv, you'd better use a servlet. I did it and it works well with 50000 rows. Here is my demo code :

public class CsvServlet extends HttpServlet {

    @Override
    protected void doGet(HttpServletRequest hsr, HttpServletResponse response) throws ServletException, IOException {
        response.setStatus(HttpServletResponse.SC_OK);
        response.setHeader("Content-Disposition", "attachment;filename=test.csv");
        response.setContentType ("application/csv");
        PrintWriter pw = response.getWriter();
        for (int i=0; i<50000; i++) {
            pw.print(i);
            for (char c: "ABCDEFGHIJKLMNOPQRSTUVWXYZ".toCharArray()) {
                pw.print(',');
                pw.print(c);
            }
            pw.println();
        }
    }

}