package com.elastisys.scale.commons.rest.converters;
import static com.google.common.base.Preconditions.checkArgument;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.Reader;
import java.lang.annotation.Annotation;
import java.lang.reflect.Type;
import javax.ws.rs.Consumes;
import javax.ws.rs.WebApplicationException;
import javax.ws.rs.client.Client;
import javax.ws.rs.core.Application;
import javax.ws.rs.core.MediaType;
import javax.ws.rs.core.MultivaluedMap;
import javax.ws.rs.core.Response;
import javax.ws.rs.core.Response.Status;
import javax.ws.rs.ext.MessageBodyReader;
import javax.ws.rs.ext.Provider;
import com.elastisys.scale.commons.json.JsonUtils;
import com.elastisys.scale.commons.rest.types.ErrorType;
import com.google.common.base.Charsets;
import com.google.common.io.CharStreams;
import com.google.gson.JsonObject;
import com.google.gson.JsonParseException;
/**
* A {@link MessageBodyReader} that can de-serialize JSON values from an entity
* stream to a {@link JsonObject}.
* <p/>
* On the server-side, it needs to be registered as a {@link Provider} class in
* the {@link Application}.
* <p/>
* On the client-side, it needs to be registered as a {@link Provider} class on
* the {@link Client} object.
*
*
*/
@Provider
@Consumes(MediaType.APPLICATION_JSON)
public class JsonObjectMessageBodyReader implements
MessageBodyReader<JsonObject> {
@Override
public boolean isReadable(Class<?> type, Type genericType,
Annotation[] annotations, MediaType mediaType) {
return JsonObject.class.isAssignableFrom(type);
}
@Override
public JsonObject readFrom(Class<JsonObject> type, Type genericType,
Annotation[] annotations, MediaType mediaType,
MultivaluedMap<String, String> httpHeaders, InputStream entityStream)
throws IOException, WebApplicationException {
try (Reader entityReader = new InputStreamReader(entityStream,
Charsets.UTF_8)) {
String entity = CharStreams.toString(entityReader);
checkArgument(entity != null,
"failed to parse JSON object: entity stream is null");
checkArgument(!entity.isEmpty(),
"failed to parse JSON object: entity stream is empty");
return JsonUtils.parseJsonString(entity);
} catch (IllegalArgumentException e) {
// produce a 400 http response
throw new WebApplicationException(e, Response
.status(Status.BAD_REQUEST).entity(new ErrorType(e))
.build());
} catch (JsonParseException e) {
// produce a 400 http response
throw new WebApplicationException(e, Response
.status(Status.BAD_REQUEST).entity(new ErrorType(e))
.build());
}
}
}