Does Java HTTP Client handle compression

问题

I tried to find any mention of handling of compression in new Java HTTP Client but failed. Is there a built-in configuration to handle for e.g. gzip or deflate compression?

I would expect to have a BodyHandler for e.g. something like this:

HttpResponse.BodyHandlers.ofGzipped(HttpResponse.BodyHandlers.ofString())

but I don't see any. I don't see any configuration in HttpClient either. Am I looking in the wrong place or was this intentionally not implemented and deferred to support libraries?

回答1:

No, gzip/deflate compression are not handled by default. You would have to implement that in your application code if you need it - e.g. by providing a customized BodySubscriber to handle it. Alternatively - you may want to have a look at whether some of the reactive stream libraries out there offer such a feature, in which case you might be able to pipe that in by using one of the BodyHandlers.fromSubscriber(Flow.Subscriber<? super List<ByteBuffer>> subscriber) or BodyHandlers.ofPublisher() methods.

回答2:

I was also surprised that the new java.net.http framework doesn't handle this automatically, but the following works for me to handle HTTP responses which are received as an InputStream and are either uncompressed or compressed with gzip:

public static InputStream getDecodedInputStream(
        HttpResponse<InputStream> httpResponse) {
    String encoding = determineContentEncoding(httpResponse);
    try {
        switch (encoding) {
            case "":
                return httpResponse.body();
            case "gzip":
                return new GZIPInputStream(httpResponse.body());
            default:
                throw new UnsupportedOperationException(
                        "Unexpected Content-Encoding: " + encoding);
        }
    } catch (IOException ioe) {
        throw new UncheckedIOException(ioe);
    }
}

public static String determineContentEncoding(
        HttpResponse<?> httpResponse) {
    return httpResponse.headers().firstValue("Content-Encoding").orElse("");
}

Note that I've not added support for the "deflate" type (because I don't currently need it, and the more I read about "deflate" the more of a mess it sounded). But I believe you can easily support "deflate" by adding a check to the above switch block and wrapping the httpResponse.body() in an InflaterInputStream.

来源：https://stackoverflow.com/questions/53502626/does-java-http-client-handle-compression

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java

java-11

java-http-client