Java tutorial
/* * Copyright 2000-2018 Vaadin Ltd. * * Licensed 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 com.vaadin.server; import java.io.File; import java.io.FileInputStream; import java.io.FileNotFoundException; import com.vaadin.util.FileTypeResolver; /** * <code>FileResources</code> are files or directories on local filesystem. The * files and directories are served through URI:s to the client terminal and * thus must be registered to an URI context before they can be used. The * resource is automatically registered to the application when it is created. * * @author Vaadin Ltd. * @since 3.0 */ @SuppressWarnings("serial") public class FileResource implements ConnectorResource { /** * Default buffer size for this stream resource. */ private int bufferSize = 0; /** * File where the downloaded content is fetched from. */ private File sourceFile; /** * Default cache time for this stream resource. */ private long cacheTime = DownloadStream.DEFAULT_CACHETIME; /** * Creates a new file resource for providing given file for client * terminals. * * @param sourceFile * the file that should be served. */ public FileResource(File sourceFile) { if (sourceFile == null) { throw new IllegalArgumentException("File cannot be null"); } setSourceFile(sourceFile); } @Override public DownloadStream getStream() { try { final DownloadStream ds = new DownloadStream(new FileInputStream(sourceFile), getMIMEType(), getFilename()); ds.setParameter("Content-Length", String.valueOf(sourceFile.length())); ds.setBufferSize(getBufferSize()); ds.setCacheTime(getCacheTime()); return ds; } catch (final FileNotFoundException e) { throw new RuntimeException("File not found: " + sourceFile.getName(), e); } } /** * Gets the source file. * * @return the source File. */ public File getSourceFile() { return sourceFile; } /** * Sets the source file. * * @param sourceFile * the source file to set. */ private void setSourceFile(File sourceFile) { this.sourceFile = sourceFile; } @Override public String getFilename() { return sourceFile.getName(); } @Override public String getMIMEType() { return FileTypeResolver.getMIMEType(sourceFile); } /** * Gets the length of cache expiration time. This gives the adapter the * possibility cache streams sent to the client. The caching may be made in * adapter or at the client if the client supports caching. Default is * <code>DownloadStream.DEFAULT_CACHETIME</code>. * * @return Cache time in milliseconds. */ public long getCacheTime() { return cacheTime; } /** * Sets the length of cache expiration time. This gives the adapter the * possibility cache streams sent to the client. The caching may be made in * adapter or at the client if the client supports caching. Zero or negative * value disables the caching of this stream. * * @param cacheTime * the cache time in milliseconds. */ public void setCacheTime(long cacheTime) { this.cacheTime = cacheTime; } /** * Gets the size of the download buffer used for this resource. * * <p> * If the buffer size is 0, the buffer size is decided by the terminal * adapter. The default value is 0. * </p> * * @return the size of the buffer in bytes. */ public int getBufferSize() { return bufferSize; } /** * Sets the size of the download buffer used for this resource. * * @param bufferSize * the size of the buffer in bytes. */ public void setBufferSize(int bufferSize) { this.bufferSize = bufferSize; } }