okhttp 3:如何使用Java/Android手动解压缩gzip/deflate响应 [英] okhttp 3: how to decompress gzip/deflate response manually using Java/Android

问题描述

我知道okhttp3库默认情况下会添加标头Accept-Encoding: gzip并自动为我们解码响应.

I know that okhttp3 library by default it adds the header Accept-Encoding: gzip and decodes the response automatically for us.

我正在处理的主机仅接受标头之类的问题:Accept-Encoding: gzip, deflate如果不添加deflate部分，它将失败.现在，当我手动将该标头添加到okhttp客户端时，该库不再对我进行解压缩.

The problem I'm dealing with a host that only accepts a header like: Accept-Encoding: gzip, deflate if I don't add the deflate part it fails. Now when I manually add that header to okhttp client, the library doesn't do the decompression anymore for me.

我已经尝试了多种解决方案来获取响应并尝试手动解压缩该响应，但是我总是最终遇到异常，例如java.util.zip.ZipException: Not in GZIP format，这是我到目前为止已经尝试过的方法:

I've tried multiple solutions to take the response and try to manually decompress that but I've always ended up with an exception i.e. java.util.zip.ZipException: Not in GZIP format, here's what I've tried so far:

//decompresser
public static String decompressGZIP(InputStream inputStream) throws IOException
{
    InputStream bodyStream = new GZIPInputStream(inputStream);
    ByteArrayOutputStream outStream = new ByteArrayOutputStream();
    byte[] buffer = new byte[4096];
    int length;
    while ((length = bodyStream.read(buffer)) > 0) 
    {
        outStream.write(buffer, 0, length);
    }

    return new String(outStream.toByteArray());
}


//run scraper
scrape(api, new Callback()
{
    // Something went wrong
    @Override
    public void onFailure(@NonNull Call call, @NonNull IOException e)
    {
    }

    @Override
    public void onResponse(@NonNull Call call, @NonNull Response response) throws IOException
    {
        if (response.isSuccessful())
        {
            try
            {
                InputStream responseBodyBytes = responseBody.byteStream();
                returnedObject = GZIPCompression.decompress(responseBodyBytes);

                if (returnedObject != null)
                {
                    String htmlResponse = returnedObject.toString();
                }
            }
            catch (ProtocolException e){}

            if(response != null) response.close();
        }
    }
});



private Call scrape(Map<?, ?> api, Callback callback)
{
    MediaType JSON = MediaType.parse("application/json; charset=utf-8");
    String method = (String) api.get("method");
    String url = (String) api.get("url");
    Request.Builder requestBuilder = new Request.Builder().url(url);
    RequestBody requestBody;

    requestBuilder.header("User-Agent", "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:61.0) Gecko/20100101 Firefox/61.0");
    requestBuilder.header("Accept", "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8");
    requestBuilder.header("Accept-Language", "en-US,en;q=0.5");
    requestBuilder.header("Accept-Encoding", "gzip, deflate");
    requestBuilder.header("Connection", "keep-alive");
    requestBuilder.header("Upgrade-Insecure-Requests", "1");
    requestBuilder.header("Cache-Control", "max-age=0");

    Request request = requestBuilder.build();

    Call call = client.newCall(request);
    call.enqueue(callback);

    return call;
}

仅需注意，响应头将始终返回Content-Encoding: gzip和Transfer-Encoding: chunked

Just a note, the response headers will always return Content-Encoding: gzip and Transfer-Encoding: chunked

还有一件事，我也在本主题中尝试了该解决方案，但对于D/OkHttp: java.io.IOException: ID1ID2: actual 0x00003c68 != expected 0x00001f8b仍然失败.

One more thing, I've also tried the solution in this topic and it still fails with D/OkHttp: java.io.IOException: ID1ID2: actual 0x00003c68 != expected 0x00001f8b.

任何帮助将不胜感激.

推荐答案

经过6个小时的挖掘，我找到了正确的解决方案，并且比往常想像的要容易，所以我基本上是在尝试解压缩未压缩的页面那就是失败的原因.现在，一旦我进入第二页(压缩的页面)，我就会得到一个压缩的响应，上面的代码应该在该响应上进行处理.另外，如果有人想要解决方案，我就像此答案中的拦截器一样使用了经过改进的拦截器，因此您无需使用一个自定义函数来处理减压.

After 6 hours of digging I found the correct solution and as usual it was easier than I thought, so I was basically trying to decompress a page that's not gzipped for that reason it was failing. Now once I hit the second page (which is compressed) I get a gzipped response where the code above should handle it. Also if anyone wants the solution I used a modified interceptor just like the one in this answer so you don't need to use a custom function to handle the decompression.

我修改了unzip方法，以使okhttp interceptor可以处理压缩和未压缩的响应:

I modified the unzip method to make the okhttp interceptor work with compressed and uncompressed responses:

    OkHttpClient.Builder clientBuilder = new OkHttpClient.Builder().addInterceptor(new UnzippingInterceptor());
    OkHttpClient client = clientBuilder.build();

拦截器就像dis:

private class UnzippingInterceptor implements Interceptor {
    @Override
    public Response intercept(Chain chain) throws IOException {
        Response response = chain.proceed(chain.request());
        return unzip(response);


    // copied from okhttp3.internal.http.HttpEngine (because is private)
    private Response unzip(final Response response) throws IOException
    {
        if (response.body() == null)
        {
            return response;
        }

        //check if we have gzip response
        String contentEncoding = response.headers().get("Content-Encoding");

        //this is used to decompress gzipped responses
        if (contentEncoding != null && contentEncoding.equals("gzip"))
        {
            Long contentLength = response.body().contentLength();
            GzipSource responseBody = new GzipSource(response.body().source());
            Headers strippedHeaders = response.headers().newBuilder().build();
            return response.newBuilder().headers(strippedHeaders)
                    .body(new RealResponseBody(response.body().contentType().toString(), contentLength, Okio.buffer(responseBody)))
                    .build();
        }
        else
        {
            return response;
        }
    }
}
}

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