使用分块http传输时获取文件总长度 [英] Getting total file length when using chunked http transfers

问题描述

我已经用Java写了一个程序来使用chunking通过http下载大文件。一切工作正常，但我想添加一个进度条，我不能做，除非我得到的文件的总长度。有没有办法做到这一点？

解决方案

如果服务器提供 Content-Length 标题字段，那很简单。如果没有的话，那么你的运气不好。

合理的服务器实现提供了 Content-Length 内容是静态的并且具有已知的大小。如果内容是动态生成的，那么不可能知道先验的长度，至少不需要进行两次数据传递。

I've written a program in Java to use chunking to download large files over http. Everything is working fine but I'd like to add a progress bar which I can't do unless I get the total length of the file. Is there any way to do this?

解决方案

If the server provides a Content-Length header field, then that's easy. If it doesn't, then you're out of luck.

Reasonable server implementations provide Content-Length when the content is static and has a known size. If the content is dynamically generated, then it's impossible to know the length a priori, at least without making two passes through the data.

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