如果我检查＆QUOT;内容长度＆QUOT;头，是不是100％准确？ [英] If I check the "content-length" header, is it 100% accurate?

问题描述

如果不是，如何准确的吗？

If not, how accurate is it?

我想知道图像的大小之前，我下载。

I want to know the size of the image before I download it.

推荐答案

这最好是 - ？不然为什么有它在所有

It had better be - otherwise why have it at all?

如果它不能可靠在先进确定的，它不应该由服务器在所有服务。 （当处理动态生成的文本处理，例如，像分块可以使用的传输编码 - 这不需要最终长度时HTTP头是在流的开始写入是已知的。）

If it can't be reliably determined in advanced, it shouldn't be served by the server at all. (When dealing with dynamically generated text, for example, something like chunked transfer encoding may be used - which doesn't require the final length to be known when the HTTP header is written at the beginning of the stream.)

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