package org.jboss.resteasy.plugins.cache.server;
import org.jboss.resteasy.spi.interception.MessageBodyWriterContext;
import org.jboss.resteasy.spi.interception.MessageBodyWriterInterceptor;
import org.jboss.resteasy.annotations.interception.ServerInterceptor;
import org.jboss.resteasy.spi.HttpRequest;
import org.jboss.resteasy.spi.NoLogWebApplicationException;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.CacheControl;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.EntityTag;
import javax.ws.rs.core.HttpHeaders;
import javax.ws.rs.core.Request;
import javax.ws.rs.core.Response;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.security.MessageDigest;
import java.security.NoSuchAlgorithmException;
/**
* @author <a href="mailto:bill@burkecentral.com">Bill Burke</a>
* @version $Revision: 1 $
*/
@ServerInterceptor
public class ServerCacheInterceptor implements MessageBodyWriterInterceptor
{
protected ServerCache cache;
public ServerCacheInterceptor(ServerCache cache)
{
this.cache = cache;
}
@Context
protected HttpRequest request;
@Context
protected Request validation;
private static final String pseudo[] = {"0", "1", "2",
"3", "4", "5", "6", "7", "8",
"9", "A", "B", "C", "D", "E",
"F"};
public static String byteArrayToHexString(byte[] bytes)
{
byte ch = 0x00;
StringBuffer out = new StringBuffer(bytes.length * 2);
for (byte b : bytes)
{
ch = (byte) (b & 0xF0);
ch = (byte) (ch >>> 4);
ch = (byte) (ch & 0x0F);
out.append(pseudo[(int) ch]);
ch = (byte) (b & 0x0F);
out.append(pseudo[(int) ch]);
}
String rslt = new String(out);
return rslt;
}
protected String createHash(byte[] entity)
{
try
{
MessageDigest messagedigest = MessageDigest.getInstance("MD5");
byte abyte0[] = messagedigest.digest(entity);
return byteArrayToHexString(abyte0);
}
catch (NoSuchAlgorithmException e)
{
throw new RuntimeException(e);
}
}
public void write(MessageBodyWriterContext context) throws IOException, WebApplicationException
{
if (!request.getHttpMethod().equalsIgnoreCase("GET") || request.getAttribute(ServerCacheHitInterceptor.DO_NOT_CACHE_RESPONSE) != null)
{
context.proceed();
return;
}
Object occ = context.getHeaders().getFirst(HttpHeaders.CACHE_CONTROL);
if (occ == null)
{
context.proceed();
return;
}
CacheControl cc = null;
if (occ instanceof CacheControl) cc = (CacheControl) occ;
else
{
cc = CacheControl.valueOf(occ.toString());
}
if (cc.isNoCache())
{
context.proceed();
return;
}
ByteArrayOutputStream buffer = new ByteArrayOutputStream();
OutputStream old = context.getOutputStream();
try
{
context.setOutputStream(buffer);
context.proceed();
byte[] entity = buffer.toByteArray();
Object etagObject = context.getHeaders().getFirst(HttpHeaders.ETAG);
String etag = null;
if (etagObject == null)
{
etag = createHash(entity);
context.getHeaders().putSingle(HttpHeaders.ETAG, etag);
}
else // use application provided ETag if it exists
{
etag = etagObject.toString();
}
cache.add(request.getUri().getRequestUri().toString(), context.getMediaType(), cc, context.getHeaders(), entity, etag);
// check to see if ETags are the same. If they are, we don't need to send a response back.
Response.ResponseBuilder validatedResponse = validation.evaluatePreconditions(new EntityTag(etag));
if (validatedResponse != null)
{
throw new NoLogWebApplicationException(validatedResponse.status(Response.Status.NOT_MODIFIED).cacheControl(cc).header(HttpHeaders.ETAG, etag).build());
}
old.write(entity);
}
finally
{
context.setOutputStream(old);
}
}
}