JAXBContextHolder.java

import static com.google.common.base.Throwables.getRootCause;
import static com.google.common.base.Throwables.propagate;

import java.util.concurrent.ExecutionException;

import javax.xml.bind.JAXBContext;
import javax.xml.bind.JAXBException;

import com.google.common.annotations.VisibleForTesting;
import com.google.common.cache.CacheBuilder;
import com.google.common.cache.CacheLoader;
import com.google.common.cache.LoadingCache;
import com.google.inject.Singleton;

@Singleton
public class JAXBContextHolder {

  private final LoadingCache<Class, JAXBContext> cache =
      CacheBuilder.newBuilder()
          .build(new CacheLoader<Class, JAXBContext>() {
            @Override
            public JAXBContext load(Class clazz) throws Exception {
              return getNewJAXBContext(clazz);
            }
          });

  public JAXBContext getContext(Class clazz) {
    try {
      return cache.get(clazz);
    } catch (ExecutionException e) {
      throw propagate(getRootCause(e));
    }
  }
  
  @VisibleForTesting
  JAXBContext getNewJAXBContext(Class clazz) throws JAXBException {
    return JAXBContext.newInstance(clazz);
  }

}