Koa-compress不起作用 [英] Koa-compress is not working

问题描述

这是我嵌入koa-compress中间件的代码

This is my code for embedding koa-compress middleware

app.use(compress({
    filter: function (content_type) {
        return /text/i.test(content_type)
    },
    threshold: 1,
    flush: require('zlib').Z_SYNC_FLUSH
}))

以下是我的回复发送代码

And following is my response sending code

ctx.body = 'Hello world'
ctx.compress = true
ctx.set('Content-Type', 'text/plain')
ctx.set('content-encoding', 'gzip')

当我通过CURL到达URL时，我得到一个简单的纯文本，上面写着"Hello World"，但我相信我应该得到一个压缩字符串，因为CURL默认情况下不进行解压缩.当我在ChromeBrowser上点击相同的URL时，出现错误消息ERR_CONTENT_DECODING_FAILED

When I hit the URL through CURL I get a simple plain text saying "Hello World" but I believe I should have I got a compressed string because CURL doesn't do decompression by default. And when I hit the same URL on ChromeBrowser, I get the error saying ERR_CONTENT_DECODING_FAILED

当我将content-encoding设置为gzip时，koa-compress应该已经压缩了我的响应文本，但是以某种方式却没有这样做.也许我在犯一些错误，但我不知道是什么?

When I set content-encoding to gzip, koa-compress should have compressed my response text but it's somehow not doing so. Maybe I'm making some mistake but I don't know what?

推荐答案

我再次重新测试了整个过程，我意识到我的代码无法正常工作，因为我已经手动设置了content-encoding，我不应该设置和设置它应该由压缩中间件本身设置.我在假设中犯了一个错误，那就是应始终压缩响应.但是，经过大量研究，我现在才意识到，压缩仅在客户端使用Accept-Encoding发送标头时才有效.如果支持的Accept-Encoding为gzip，则响应为deflate时将以gzip压缩，响应应以deflate形式进行压缩，如果未提及，则响应应为简单的纯数据.我在curl中收到纯文本，因为curl不会在默认请求中发送Accept-Encoding，但是当我使用以下代码发送curl请求时

I just retested the whole process once again and I realised that my code was not working because I had manually set content-encoding, which I should not have set and it should be set by compression middleware itself. I was making mistakes in assuming that response should always be compressed. But what I realised now, after lots of research is that compression works only when the client sends a header with Accept-Encoding. If supported Accept-Encoding is gzip, the response will be compressed in gzip if it's deflate, the response shall be compressed in deflate form, and if it's not mentioned response shall be simple plain data. I was receiving plain text in curl because curl does not send Accept-Encoding in its default request, but when I sent curl request using following code

curl -H 'Accept-Encoding: gzip' -D - http://localhost:3000 

然后我收到了压缩形式的回复.所以我的代码一直在工作.只是我不应该已设置

then I received the response in compressed form. So my code has been working for always. Just that I should NOT have set

ctx.set('content-encoding', 'gzip')

如果设置了content-encoding，则模块将无法运行并产生错误 因此我们不必显式设置内容编码，它应该由压缩中间件根据请求的Accept-Encoding设置.

If content-encoding is set, the module will not run and produce error so we don't have to explicitly set the content-encoding, it should be set by compression middleware depending on Accept-Encoding of the request.

因此正确的响应代码应如下所示

So the correct code to response should be like following

ctx.body = 'Hello world'
ctx.compress = true
ctx.set('Content-Type', 'text/plain')

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