如何在java的http头中将内容长度设置为long值？

Question

I am writing a web server in java that is transferring file upto 2GB fine. When I searched for the reason, I found like java HttpServelet only allows us to set the content length as int. As the maximum size of integer is 2GB, its working fine upto 2gb when I am using response.setContentLength method. Now the problem is bydefault response.setContentLength has the parameter of integer. So it is not taking long value as parameter. I have already tried response.setHeader("Content-Length", Long.toString(f.length())); response.addHeader("Content-Length", Long.toString(f.length())); but nothing is working. All time it is failing to add content length when it is a long value. So please give any working solution for HTTPServletResponse so that I can set the content length as long value.

Answer 1

You can also use below sample code.

long length = fileObj.length();

if (length <= Integer.MAX_VALUE)
{
  response.setContentLength((int)length);
}
else
{
  response.addHeader("Content-Length", Long.toString(length));
}

Answer 2

Try this:

long length = ...;
response.setHeader("Content-Length", String.valueOf(length))

Hope this helps...

Answer 3

Don't set it at all.

Just let it use chunked transfer mode, which is the default. There is no Content-Length header in that circumstance. See @BalusC's comment under this question .

Answer 4

Do not set it and use chunked encoding. Also beware of HEAD requests = these requests should return the same content-length as GET , but not sending the actual body. Default implementation of HEAD in javax.servlet.http.HttpServlet is done by calling GET on the same URL and ignoring all the response body written (only counting characters) - see the following fragment:

protected void doHead(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
    NoBodyResponse response = new NoBodyResponse(resp); // mock response (not writing)
    doGet(req, response); // performs a normal GET request
    response.setContentLength(); // this uses INTEGER counter only
}

The problem is that the content length counter is also integer. So I recommend overloading doHead method also and not setting the content length at all (you might want to leave GET call also to save time generating the giant file).

Answer 5

就像java中的数组一样，在你的情况下你不能超过2 GB。