Java tutorial
/* * Licensed to the Apache Software Foundation (ASF) under one * or more contributor license agreements. See the NOTICE file * distributed with this work for additional information * regarding copyright ownership. The ASF licenses this file * to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance * with the License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, * software distributed under the License is distributed on an * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY * KIND, either express or implied. See the License for the * specific language governing permissions and limitations * under the License. * */ package org.apache.openaz.xacml.admin.util; import java.io.IOException; import com.vaadin.server.FileDownloader; import com.vaadin.server.StreamResource; import com.vaadin.server.StreamResource.StreamSource; import com.vaadin.server.VaadinRequest; import com.vaadin.server.VaadinResponse; import com.vaadin.ui.UI; public class OnDemandFileDownloader extends FileDownloader { private static final long serialVersionUID = 1L; private final OnDemandStreamResource resource; public interface OnDemandStreamResource extends StreamSource { String getFilename(); } public OnDemandFileDownloader(OnDemandStreamResource resource) { super(new StreamResource(resource, "")); this.resource = resource; if (this.resource == null) { throw new NullPointerException("Can't send null resource"); } } @Override public boolean handleConnectorRequest(VaadinRequest request, VaadinResponse response, String path) throws IOException { this.getResource().setFilename(this.resource.getFilename()); return super.handleConnectorRequest(request, response, path); } private StreamResource getResource() { StreamResource resource = null; UI.getCurrent().getSession().lock(); try { resource = (StreamResource) this.getResource("dl"); } finally { UI.getCurrent().getSession().unlock(); } return resource; } }