Using Apache HTTPClient 4.x for MultiPart uploads with Jersey 1.x Server

You can easily find a lot of articles on the web describing the process to use Jersey client with a Jersey 1.x Server to do multi-part uploads. However, when trying to use Apache HTTP client, it uncovers a bug in jersey causing a NullPointerException – https://java.net/jira/browse/JERSEY-1658

SEVERE: The RuntimeException could not be mapped to a response, re-throwing to the HTTP container
java.lang.NullPointerException
    at     com.sun.jersey.multipart.impl.MultiPartReaderClientSide.unquoteMediaTypeParameters(MultiPartReaderClientSide.java:227)
    at com.sun.jersey.multipart.impl.MultiPartReaderClientSide.readMultiPart(MultiPartReaderClientSide.java:154)
    at com.sun.jersey.multipart.impl.MultiPartReaderServerSide.readMultiPart(MultiPartReaderServerSide.java:80)
    at com.sun.jersey.multipart.impl.MultiPartReaderClientSide.readFrom(MultiPartReaderClientSide.java:144)
    at com.sun.jersey.multipart.impl.MultiPartReaderClientSide.readFrom(MultiPartReaderClientSide.java:82)
    at com.sun.jersey.spi.container.ContainerRequest.getEntity(ContainerRequest.java:488)
    at com.sun.jersey.server.impl.model.method.dispatch.EntityParamDispatchProvider$EntityInjectable.getValue(EntityParamDispatchProvider.java:123)
    at com.sun.jersey.server.impl.inject.InjectableValuesProvider.getInjectableValues(InjectableValuesProvider.java:46)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$EntityParamInInvoker.getParams(AbstractResourceMethodDispatchProvider.java:153)
    at com.sun.jersey.server.impl.model.method.dispatch.AbstractResourceMethodDispatchProvider$ResponseOutInvoker._dispatch(AbstractResourceMethodDispatchProvider.java:203)
    at com.sun.jersey.server.impl.model.method.dispatch.ResourceJavaMethodDispatcher.dispatch(ResourceJavaMethodDispatcher.java:75)

Here’s the relevant piece of code from Jersey

protected static MediaType unquoteMediaTypeParameters(final MediaType mediaType, final String... parameters) {
235        if (parameters == null || parameters.length == 0) {
236            return mediaType;
237        }
238
239        final HashMap unquotedParams = new HashMap(mediaType.getParameters());
240
241        for (final String parameterName : parameters) {
242            String parameterValue = mediaType.getParameters().get(parameterName);
243
244            if (parameterValue.startsWith("\"")) {
245                parameterValue = parameterValue.substring(1, parameterValue.length() - 1);
246                unquotedParams.put(parameterName, parameterValue);
247            }
248        }
249
250        return new MediaType(mediaType.getType(), mediaType.getSubtype(), unquotedParams);
251    }

The error occurs because Jersey Server expects the boundary parameter be set as a part of the content-type header, which is not being set by Apache HTTP Client. It can be verified by looking at the request made by Jersey client vs Apache client

Jersey Client

Content-Type=multipart/form-data;boundary=Boundary-1234567890

Apache HTTP Client

Content-Type=multipart/form-data

And since the boundary parameter is missing, it ends up throwing a NPE.

SOLUTION

I was able manually hack in the boundary parameter into the Content-Type header of the request making it available for Jersey parser and thus avoiding the NPE. The issue with this fix however is that the class MultipartFormEntity is package private and therefore, the utility class described below needs to be created in the package org.apache.http.entity.mime

package org.apache.http.entity.mime;

import org.apache.commons.lang3.Validate;
import org.apache.http.HttpEntity;

public class MultiPartEntityUtil {
	
	public static String getBoundaryValue(HttpEntity entity) {
		Validate.notNull(entity);
		
		if( entity instanceof MultipartFormEntity ) {
			MultipartFormEntity formEntity = (MultipartFormEntity)entity;

			AbstractMultipartForm form =  formEntity.getMultipart();
			Validate.notNull(form);
			
			return form.getBoundary();
		}
		
		throw new IllegalArgumentException("Provided entity is of type: " + entity.getClass() + " instead of expected: MultipartFormEntity");
	}

}

With this utility class, we can simply set the Content-Type header as follows

 MultipartEntityBuilder builder = MultipartEntityBuilder.create();
 builder.setMode(HttpMultipartMode.BROWSER_COMPATIBLE);

for (File file : files) {
    builder.addBinaryBody(file.getName(), file, ContentType.DEFAULT_BINARY, file.getName());
}

HttpEntity entity = builder.build();
String boundary= MultiPartEntityUtil.getBoundaryValue(entity);

...

request.addHeader(HttpHeaders.CONTENT_TYPE, "multipart/form-data;boundary="+boundary);

This hack makes sure that Jersey server finds the appropriate boundary parameter. Now you can successfully do multipart uploads with Apache client on Jersey 1.x

Jersey Filters – ContainerRequestFilter and ContainerResponseFilter

Jersey Filters allow a certain functionality to the performed on every request/response. They are typically used to modify request or response parameters like headers. Jersey user guide provides a good description of what filters can do. This blog however focusses on how to set up filters in Jersey based on different jersey versions

Jersey 1.x

The core of setting up is configuring the appropriate init parameter. In Jersey 1.x, these were

setInitParameter(ResourceConfig.PROPERTY_CONTAINER_REQUEST_FILTERS, RequestResponseLoggingFilter.class.getName());
setInitParameter(ResourceConfig.PROPERTY_CONTAINER_RESPONSE_FILTERS, RequestResponseLoggingFilter.class.getName());

where the parameter keys were

public static final String PROPERTY_CONTAINER_REQUEST_FILTERS =  "com.sun.jersey.spi.container.ContainerRequestFilters";
public static final String PROPERTY_CONTAINER_RESPONSE_FILTERS =  "com.sun.jersey.spi.container.ContainerResponseFilters";

These parameters can also be set using web.xml

<servlet>  
    <servlet-name>Jersey REST Service</servlet-name>  
    <servlet-class>org.glassfish.jersey.servlet.ServletContainer</servlet-class>  
    <init-param>
        <param-name>com.sun.jersey.spi.container.ContainerRequestFilters</param-name>
        <param-value>com.company.org.jersey.filters.RequestResponseLogginFilter</param-value>
    </init-param>
</servlet>

Jersey 2.x

In Jersey 2.x the parameters changed to the following

setInitParameter("javax.ws.rs.container.ContainerRequestFilter", RequestResponseLoggingFilter.class.getName());
setInitParameter( "javax.ws.rs.container.ContainerResponseFilter", RequestResponseLoggingFilter.class.getName());