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package org.glassfish.jersey.examples.httppatch;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.lang.annotation.Annotation;
import java.lang.reflect.Method;
import javax.ws.rs.GET;
import javax.ws.rs.InternalServerErrorException;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.core.Context;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedHashMap;
import javax.ws.rs.core.UriInfo;
import javax.ws.rs.ext.MessageBodyWriter;
import javax.ws.rs.ext.ReaderInterceptor;
import javax.ws.rs.ext.ReaderInterceptorContext;
import org.glassfish.jersey.message.MessageBodyWorkers;
import com.fasterxml.jackson.databind.JsonNode;
import com.fasterxml.jackson.databind.ObjectMapper;
import com.github.fge.jsonpatch.JsonPatch;
import com.github.fge.jsonpatch.JsonPatchException;
/**
* JAX-RS reader interceptor that implements server-side PATCH support.
*
* @author Gerard Davison (gerard.davison at oracle.com)
* @author Marek Potociar (marek.potociar at oracle.com)
*/
@PATCH
public class PatchingInterceptor implements ReaderInterceptor {
/**
* Supported PATCH data format.
*/
public static final String PATCH_MEDIA_TYPE = "application/json-patch+json";
private final UriInfo uriInfo;
private final MessageBodyWorkers workers;
/**
* {@code PatchingInterceptor} injection constructor.
*
* @param uriInfo {@code javax.ws.rs.core.UriInfo} proxy instance.
* @param workers {@link org.glassfish.jersey.message.MessageBodyWorkers} message body workers.
*/
public PatchingInterceptor(@Context UriInfo uriInfo, @Context MessageBodyWorkers workers) {
this.uriInfo = uriInfo;
this.workers = workers;
}
@SuppressWarnings("unchecked")
@Override
public Object aroundReadFrom(ReaderInterceptorContext readerInterceptorContext) throws IOException, WebApplicationException {
// Get the resource we are being called on, and find the GET method
Object resource = uriInfo.getMatchedResources().get(0);
Method found = null;
for (Method next : resource.getClass().getMethods()) {
if (next.getAnnotation(GET.class) != null) {
found = next;
break;
}
}
if (found == null) {
throw new InternalServerErrorException("No matching GET method on resource");
}
// Invoke the get method to get the state we are trying to patch
Object bean;
try {
bean = found.invoke(resource);
} catch (Exception e) {
throw new WebApplicationException(e);
}
// Convert this object to a an array of bytes
ByteArrayOutputStream baos = new ByteArrayOutputStream();
MessageBodyWriter bodyWriter =
workers.getMessageBodyWriter(bean.getClass(), bean.getClass(),
new Annotation[0], MediaType.APPLICATION_JSON_TYPE);
bodyWriter.writeTo(bean, bean.getClass(), bean.getClass(),
new Annotation[0], MediaType.APPLICATION_JSON_TYPE,
new MultivaluedHashMap<String, Object>(), baos);
// Use the Jackson 2.x classes to convert both the incoming patch
// and the current state of the object into a JsonNode / JsonPatch
ObjectMapper mapper = new ObjectMapper();
JsonNode serverState = mapper.readValue(baos.toByteArray(), JsonNode.class);
JsonNode patchAsNode = mapper.readValue(readerInterceptorContext.getInputStream(), JsonNode.class);
JsonPatch patch = JsonPatch.fromJson(patchAsNode);
try {
// Apply the patch
JsonNode result = patch.apply(serverState);
// Stream the result & modify the stream on the readerInterceptor
ByteArrayOutputStream resultAsByteArray = new ByteArrayOutputStream();
mapper.writeValue(resultAsByteArray, result);
readerInterceptorContext.setInputStream(new ByteArrayInputStream(resultAsByteArray.toByteArray()));
// Pass control back to the Jersey code
return readerInterceptorContext.proceed();
} catch (JsonPatchException ex) {
throw new InternalServerErrorException("Error applying patch.", ex);
}
}
}