如何使用Spring RestTemplate压缩HTTP请求？

我提出了两种解决方案，一种更简单，无需流传输，另一种支持流传输。

如果您不需要流媒体，请使用custom ClientHttpRequestInterceptor，一个Spring功能。

RestTemplate rt = new RestTemplate();
rt.setInterceptors(Collections.singletonList(interceptor));

interceptor可能在哪里：

ClientHttpRequestInterceptor interceptor = new ClientHttpRequestInterceptor() {

    @Override
    public ClientHttpResponse intercept(HttpRequest request, byte[] body, ClientHttpRequestExecution execution)
            throws IOException {
        request.getHeaders().add("Content-Encoding", "gzip");
        byte[] gzipped = getGzip(body);
        return execution.execute(request, gzipped);
    } 
 }

getGzip我复制了

    private byte[] getGzip(byte[] body) throws IOException {

        ByteArrayOutputStream byteStream = new ByteArrayOutputStream();
        try {
            GZIPOutputStream zipStream = new GZIPOutputStream(byteStream);
            try {
                zipStream.write(body);
            } finally {
                zipStream.close();
            }
        } finally {
            byteStream.close();
        }

        byte[] compressedData = byteStream.toByteArray();
        return compressedData;

    }

配置拦截器后，所有请求将被压缩。

这种方法的缺点是它不支持流式传输，因为ClientHttpRequestInterceptor将内容作为byte[]

如果您需要流式传输，请创建一个custom ClientHttpRequestFactory，说出来GZipClientHttpRequestFactory，然后像这样使用它：

    SimpleClientHttpRequestFactory requestFactory = new SimpleClientHttpRequestFactory();
    requestFactory.setBufferRequestBody(false);
    ClientHttpRequestFactory gzipRequestFactory = new GZipClientHttpRequestFactory(requestFactory);
    RestTemplate rt = new RestTemplate(gzipRequestFactory);

在哪里GZipClientHttpRequestFactory：

public class GZipClientHttpRequestFactory extends AbstractClientHttpRequestFactoryWrapper {

    public GZipClientHttpRequestFactory(ClientHttpRequestFactory requestFactory) {
        super(requestFactory);
    }

    @Override
    protected ClientHttpRequest createRequest(URI uri, HttpMethod httpMethod, ClientHttpRequestFactory requestFactory)
            throws IOException {
        ClientHttpRequest delegate = requestFactory.createRequest(uri, httpMethod);
        return new ZippedClientHttpRequest(delegate);
    }

}

并且ZippedClientHttpRequest是：

public class ZippedClientHttpRequest extends WrapperClientHttpRequest
{
    private GZIPOutputStream zip;

    public ZippedClientHttpRequest(ClientHttpRequest delegate) {
        super(delegate);
        delegate.getHeaders().add("Content-Encoding", "gzip");
        // here or in getBody could add content-length to avoid chunking
        // but is it available ? 
        // delegate.getHeaders().add("Content-Length", "39");

    }

    @Override
    public OutputStream getBody() throws IOException {
        final OutputStream body = super.getBody();
        zip = new GZIPOutputStream(body);
        return zip;
    }

    @Override
    public ClientHttpResponse execute() throws IOException {
        if (zip!=null) zip.close();
        return super.execute();
    }

}

最后WrapperClientHttpRequest是：

public class WrapperClientHttpRequest implements ClientHttpRequest {

    private final ClientHttpRequest delegate;

    protected WrapperClientHttpRequest(ClientHttpRequest delegate) {
        super();
        if (delegate==null)
            throw new IllegalArgumentException("null delegate");
        this.delegate = delegate;
    }

    protected final ClientHttpRequest getDelegate() {
        return delegate;
    }

    @Override
    public OutputStream getBody() throws IOException {
        return delegate.getBody();
    }

    @Override
    public HttpHeaders getHeaders() {
        return delegate.getHeaders();
    }

    @Override
    public URI getURI() {
        return delegate.getURI();
    }

    @Override
    public HttpMethod getMethod() {
        return delegate.getMethod();
    }

    @Override
    public ClientHttpResponse execute() throws IOException {
        return delegate.execute();
    }
}

这种方法使用分块传输编码创建请求，如果知道大小，则可以设置内容长度标头来更改此请求。

ClientHttpRequestInterceptor和/或自定义ClientHttpRequestFactory方法的优点是它可以与RestTemplate的任何方法一起使用。另一种方法，传递一个RequestCallback能够仅与execute方法，这是因为RestTemplate的其它方法在内部创建他们自己的RequestCallback（S）产生的内容。

顺便说一句，似乎几乎没有支持在服务器上解压缩gzip请求。还相关：在WebRequest中发送压缩数据？指出了Zip Bomb问题。我认为您将不得不为此编写一些代码。