Java tutorial
/* * Copyright 2002-2013 the original author or authors. * * 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.dianping.resource.io; import java.io.File; import java.io.FileNotFoundException; import java.io.IOException; import java.io.InputStream; import java.io.OutputStream; import java.net.URI; import java.net.URL; import java.nio.file.Files; import java.nio.file.OpenOption; import java.nio.file.Path; import java.nio.file.Paths; import com.dianping.resource.io.util.Assert; /** * {@link Resource} implementation for {@code java.nio.file.Path} handles. * Supports resolution as File, and also as URL. * Implements the extended {@link WritableResource} interface. * * @author Philippe Marschall * @since 4.0 * @see java.nio.file.Path */ public class PathResource extends AbstractResource implements WritableResource { private final Path path; /** * Create a new PathResource from a Path handle. * <p>Note: Unlike {@link FileSystemResource}, when building relative resources * via {@link #createRelative}, the relative path will be built <i>underneath</i> the * given root: * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"! * @param path a Path handle */ public PathResource(Path path) { Assert.notNull(path, "Path must not be null"); this.path = path.normalize(); } /** * Create a new PathResource from a Path handle. * <p>Note: Unlike {@link FileSystemResource}, when building relative resources * via {@link #createRelative}, the relative path will be built <i>underneath</i> the * given root: * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"! * @param path a path * @see java.nio.file.Paths#get(String, String...) */ public PathResource(String path) { Assert.notNull(path, "Path must not be null"); this.path = Paths.get(path).normalize(); } /** * Create a new PathResource from a Path handle. * <p>Note: Unlike {@link FileSystemResource}, when building relative resources * via {@link #createRelative}, the relative path will be built <i>underneath</i> the * given root: * e.g. Paths.get("C:/dir1/"), relative path "dir2" -> "C:/dir1/dir2"! * @see java.nio.file.Paths#get(java.net.URI) * @param uri a path URI */ public PathResource(URI uri) { Assert.notNull(uri, "URI must not be null"); this.path = Paths.get(uri).normalize(); } /** * Return the file path for this resource. */ public final String getPath() { return this.path.toString(); } /** * This implementation returns whether the underlying file exists. * @see org.springframework.core.io.PathResource#exists() */ @Override public boolean exists() { return Files.exists(this.path); } /** * This implementation checks whether the underlying file is marked as readable * (and corresponds to an actual file with content, not to a directory). * @see java.nio.file.Files#isReadable(java.nio.file.Path) * @see java.nio.file.Files#isDirectory(java.nio.file.Path, java.nio.file.LinkOption...) */ @Override public boolean isReadable() { return (Files.isReadable(this.path) && !Files.isDirectory(this.path)); } /** * This implementation opens a InputStream for the underlying file. * @see java.nio.file.spi.FileSystemProvider#newInputStream(java.nio.file.Path, java.nio.file.OpenOption...) */ @Override public InputStream getInputStream() throws IOException { if (!exists()) { throw new FileNotFoundException(getPath() + " (No such file or directory)"); } if (Files.isDirectory(this.path)) { throw new FileNotFoundException(getPath() + " (Is a directory)"); } return Files.newInputStream(this.path); } /** * This implementation returns a URL for the underlying file. * @see java.nio.file.Path#toUri() * @see java.net.URI#toURL() */ @Override public URL getURL() throws IOException { return this.path.toUri().toURL(); } /** * This implementation returns a URI for the underlying file. * @see java.nio.file.Path#toUri() */ @Override public URI getURI() throws IOException { return this.path.toUri(); } /** * This implementation returns the underlying File reference. */ @Override public File getFile() throws IOException { try { return this.path.toFile(); } catch (UnsupportedOperationException ex) { // only Paths on the default file system can be converted to a File // do exception translation for cases where conversion is not possible throw new FileNotFoundException(this.path + " cannot be resolved to " + "absolute file path"); } } /** * This implementation returns the underlying File's length. */ @Override public long contentLength() throws IOException { return Files.size(this.path); } /** * This implementation returns the underlying File's timestamp. * @see java.nio.file.Files#getLastModifiedTime(java.nio.file.Path, java.nio.file.LinkOption...) */ @Override public long lastModified() throws IOException { // we can not use the super class method since it uses conversion to a File and // only Paths on the default file system can be converted to a File return Files.getLastModifiedTime(path).toMillis(); } /** * This implementation creates a FileResource, applying the given path * relative to the path of the underlying file of this resource descriptor. * @see java.nio.file.Path#resolve(String) */ @Override public Resource createRelative(String relativePath) throws IOException { return new PathResource(this.path.resolve(relativePath)); } /** * This implementation returns the name of the file. * @see java.nio.file.Path#getFileName() */ @Override public String getFilename() { return this.path.getFileName().toString(); } @Override public String getDescription() { return "path [" + this.path.toAbsolutePath() + "]"; } // implementation of WritableResource /** * This implementation checks whether the underlying file is marked as writable * (and corresponds to an actual file with content, not to a directory). * @see java.nio.file.Files#isWritable(java.nio.file.Path) * @see java.nio.file.Files#isDirectory(java.nio.file.Path, java.nio.file.LinkOption...) */ @Override public boolean isWritable() { return Files.isWritable(this.path) && !Files.isDirectory(this.path); } /** * This implementation opens a OutputStream for the underlying file. * @see java.nio.file.spi.FileSystemProvider#newOutputStream(java.nio.file.Path, java.nio.file.OpenOption...) */ @Override public OutputStream getOutputStream() throws IOException { if (Files.isDirectory(this.path)) { throw new FileNotFoundException(getPath() + " (Is a directory)"); } return Files.newOutputStream(this.path); } /** * This implementation compares the underlying Path references. */ @Override public boolean equals(Object obj) { return (obj == this || (obj instanceof PathResource && this.path.equals(((PathResource) obj).path))); } /** * This implementation returns the hash code of the underlying Path reference. */ @Override public int hashCode() { return this.path.hashCode(); } }