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okhttp 3:如何使用Java/Android手动解压缩gzip/deflate响应

deflate okhttp3 gzip android java

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Desolator · 技术社区 · 7 年前

我知道 okhttp3 库默认情况下,它添加头 Accept-Encoding: gzip 为我们自动解码。

我要处理的问题是,一个主机只接受这样的头: Accept-Encoding: gzip, deflate 如果我不加上 deflate 部分失败。现在,当我手动将该头添加到okhttp客户端时,库不再为我执行解压。

我尝试了多种解决方案来获取响应并尝试手动解压缩,但我总是以一个例外而告终,即。 java.util.zip.ZipException: Not in GZIP format ,以下是我迄今为止所做的尝试:

//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;
}

Content-Encoding: gzip 和 Transfer-Encoding: chunked

还有一件事,我也试过 this topic 但还是失败了 D/OkHttp: java.io.IOException: ID1ID2: actual 0x00003c68 != expected 0x00001f8b .

1 回复 | 直到 7 年前

1

8

Desolator 7 年前

经过6个小时的挖掘,我找到了正确的解决方案,而且和往常一样,它比我想象的要简单,所以我基本上是在尝试解压缩一个没有被gzip压缩的页面,因为它失败了。现在,一旦我进入第二页(它是压缩的),我就会得到一个gzip响应,上面的代码应该处理它。另外,如果有人想要这个解决方案,我使用了一个修改过的拦截器,就像 this answer 所以不需要使用自定义函数来处理解压。

我修改了 unzip 方法来生成okhttp interceptor 处理压缩和未压缩的响应:

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

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;
        }
    }
}
}