GZIPContentEncodingFilter.java

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package com.sun.jersey.api.container.filter;

import com.sun.jersey.api.container.ContainerException;
import com.sun.jersey.spi.container.ContainerRequest;
import com.sun.jersey.spi.container.ContainerRequestFilter;
import com.sun.jersey.spi.container.ContainerResponse;
import com.sun.jersey.spi.container.ContainerResponseFilter;
import com.sun.jersey.spi.container.ContainerResponseWriter;
import java.io.IOException;
import java.io.OutputStream;
import java.util.zip.GZIPInputStream;
import java.util.zip.GZIPOutputStream;
import javax.ws.rs.core.HttpHeaders;

/**
 * A GZIP content encoding filter.
 * <p>
 * If the request contains a Content-Encoding header of "gzip"
 * then the request entity (if any) is uncompressed using gzip.
 * <p>
 * If the request contains a Accept-Encoding header that contains
 * "gzip" then the response entity (if any) is compressed using gzip and a
 * Content-Encoding header of "gzip" is added to the response.
 * <p>
 * When an application is deployed as a Servlet or Filter this Jersey filter can be
 * registered using the following initialization parameters:
 * <blockquote><pre>
 *     <init-param>
 *         <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
 *         <param-value>com.sun.jersey.api.container.filter.GZIPContentEncodingFilter</param-value>
 *     </init-param>
 *     <init-param>
 *         <param-name>com.sun.jersey.spi.container.ContainerResponseFilters</param-name>
 *         <param-value>com.sun.jersey.api.container.filter.GZIPContentEncodingFilter</param-value>
 *     </init-param>
 * </pre></blockquote>
 *
 * @author Paul.Sandoz@Sun.Com
 * @see com.sun.jersey.api.container.filter
 */
public class GZIPContentEncodingFilter implements ContainerRequestFilter, ContainerResponseFilter {

    public ContainerRequest filter(ContainerRequest request) {
        if (request.getRequestHeaders().containsKey(HttpHeaders.CONTENT_ENCODING)) {
            if (request.getRequestHeaders().getFirst(HttpHeaders.CONTENT_ENCODING).trim().equals("gzip")) {
                request.getRequestHeaders().remove(HttpHeaders.CONTENT_ENCODING);
                try {
                    request.setEntityInputStream(
                            new GZIPInputStream(request.getEntityInputStream()));
                } catch (IOException ex) {
                    throw new ContainerException(ex);
                }
            }
        }
        return request;
    }

    private static final class Adapter implements ContainerResponseWriter {
        private final ContainerResponseWriter crw;

        private GZIPOutputStream gos;

        Adapter(ContainerResponseWriter crw) {
            this.crw = crw;
        }
        
        public OutputStream writeStatusAndHeaders(long contentLength, ContainerResponse response) throws IOException {
           gos = new GZIPOutputStream(crw.writeStatusAndHeaders(-1, response));
           return gos;
        }

        public void finish() throws IOException {
            gos.finish();
            crw.finish();
        }
    }

    public ContainerResponse filter(ContainerRequest request, ContainerResponse response) {
        if (response.getEntity() != null && 
                request.getRequestHeaders().containsKey(HttpHeaders.ACCEPT_ENCODING) &&
                !response.getHttpHeaders().containsKey(HttpHeaders.CONTENT_ENCODING)) {
            if (request.getRequestHeaders().getFirst(HttpHeaders.ACCEPT_ENCODING).contains("gzip")) {
                response.getHttpHeaders().add(HttpHeaders.CONTENT_ENCODING, "gzip");
                response.setContainerResponseWriter(
                        new Adapter(response.getContainerResponseWriter()));
            }
        }        
        return response;
    }
}