如何在JAX-RS中提供已经压缩的内容?

问题描述

我正在用Resteasy开发一个小型的JAX-RS应用程序.我希望该应用程序为Javascript和CSS文件等提供一些静态内容，并且我想利用 webjars.org .因此，我需要处理Accept-Encoding标头，并检查.gz是否存在(或不存在).

I'm developing a small JAX-RS application with Resteasy. I wanted the application to serve some static content for Javascript and CSS files, etc. and I would like to take advantage of the already gzipped version of the resources packaged in the jars of webjars.org. Thus, I need to handle the Accept-Encoding header and check if the .gz is there (or not).

到目前为止，我所拥有的是:

So far, what I have is:

@Path("res/{path:.*}")
@GET
public Response webjars(@PathParam("path") String path, @HeaderParam("Accept-Encoding") String acceptEncoding) {

    // Guesses MIME type from the path extension elsewhere.
    String mime = mimes.getContentType(path);

    if (acceptEncoding.contains("gzip")) {
        InputStream is = getClass().getResourceAsStream("/META-INF/resources/webjars/" + path + ".gz");
        if (is != null)
            return Response.ok().type(mime).encoding("gzip").entity(is).build();
    }

    InputStream is = getClass().getResourceAsStream("/META-INF/resources/webjars/" + path);
    if (is != null)
        return Response.ok().type(mime).entity(is).build();

    return Response.status(Status.NOT_FOUND).build();
}

但是它不起作用.所提供的内容已完全损坏.到目前为止，我发现有一个再次压缩流的组件: org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor 因为我手动填充Content-Encoding标头(使用ResponseBuilder.encoding方法).

But it doesn't work. The content served is totally broken. So far, I've found that a component that compresses the stream again: org.jboss.resteasy.plugins.interceptors.encoding.GZIPEncodingInterceptor because I manually filled the Content-Encoding header (using the ResponseBuilder.encoding method).

在我看来，这似乎是一个错误，因为显然，无法共享已经压缩的流.但是，使用JAX-RS是否可以实现?这是Resteasy的错误吗?

This looks like a bug to me because, apparently, there's no way to share an already gzipped stream. However, Is this achievable using JAX-RS? Is this a Resteasy bug?

我可以想到多种方法来在外部实现与Resteasy相同的功能，例如映射webjars.org servlet(我不在Servlet API 3.0环境中，因此我没有META-INF/resources/自动类路径映射) .不过，我的问题仍然存在.它适用于其他几种情况.

I can think of a variety of ways to achieve the same thing externally to Resteasy, like mapping the webjars.org servlet (I'm not in a Servlet API 3.0 environment, so I have no META-INF/resources/ automatic classpath mapping). Nevertheless, my questions still prevail. It applies to several other scenarios.

更新:

为了记录，我已填写了以下问题: RESTEASY-1170 .

For the record I have filled the issue RESTEASY-1170.

推荐答案

以下是我上面评论的示例实现.

Here's an example implementation of my above comment.

@AlreadyGzipped

@NameBinding
@Target({ElementType.METHOD, ElementType.TYPE})
@Retention(RetentionPolicy.RUNTIME)
public @interface AlreadyGzipped {}

WriterInterceptor .注意@Priority. GZIPEncodingInterceptor使用Priorities.ENTITY_CODER

@Provider
@AlreadyGzipped
@Priority(Priorities.ENTITY_CODER + 1000)
public class AlreadyGzippedWriterInterceptor implements WriterInterceptor {
    @Context HttpHeaders headers;

    @Override
    public void aroundWriteTo(WriterInterceptorContext wic) throws IOException,
                                                      WebApplicationException {
        String header = headers.getHeaderString("Accept-Encoding");
        if (null != header && header.equalsIgnoreCase("gzip")) {
            wic.getHeaders().putSingle("Content-Encoding", "gzip");
        }
        wic.proceed();
    }
}

测试资源

@Path("resource")
public class AlreadyGzippedResoure {

    @GET
    @AlreadyGzipped
    @Produces(MediaType.APPLICATION_OCTET_STREAM)
    public Response getAlreadGzipped() throws Exception {
        InputStream is = getClass().getResourceAsStream("/stackoverflow.png.gz");
        return Response.ok(is).build();
    }
}

测试

public class Main {
    public static void main(String[] args) throws Exception {
        Client client = ClientBuilder.newClient();
        String url = "http://localhost:8080/api/resource";

        Response response = client.target(url).request().acceptEncoding("gzip").get();
        Image image = ImageIO.read(response.readEntity(InputStream.class));
        JOptionPane.showMessageDialog(null,new JLabel(new ImageIcon(image)));
    }
}

结果

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