content: /*
   * Copyright 2002-2019 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
   *
   *      https://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.alibaba.nacos.common.packagescan.resource;
  
  import com.alibaba.nacos.common.packagescan.util.AbstractAssert;
  import com.alibaba.nacos.common.utils.StringUtils;
  
  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.channels.FileChannel;
  import java.nio.channels.ReadableByteChannel;
  import java.nio.channels.WritableByteChannel;
  import java.nio.file.FileSystem;
  import java.nio.file.Files;
  import java.nio.file.NoSuchFileException;
  import java.nio.file.Path;
  import java.nio.file.StandardOpenOption;
  
  /**
   * Copy from https://github.com/spring-projects/spring-framework.git, with less modifications
   * {@link Resource} implementation for {@code java.io.File} and
   * {@code java.nio.file.Path} handles with a file system target.
   * Supports resolution as a {@code File} and also as a {@code URL}.
   * Implements the extended {@link WritableResource} interface.
   *
   * <p>Note: As of Spring Framework 5.0, this {@link Resource} implementation uses
   * NIO.2 API for read/write interactions. As of 5.1, it may be constructed with a
   * {@link Path} handle in which case it will perform all file system
   * interactions via NIO.2, only resorting to {@link File} on {@link #getFile()}.
   *
   * @author Juergen Hoeller
   * @see #FileSystemResource(String)
   * @see #FileSystemResource(File)
   * @see #FileSystemResource(Path)
   * @see File
   * @see Files
   * @since 28.12.2003
   */
  public class FileSystemResource extends AbstractResource implements WritableResource {
  
      private final String path;
  
      private final File file;
  
      private final Path filePath;
  
      /**
       * Create a new {@code FileSystemResource} from a file path.
       *
       * <p>Note: When building relative resources via {@link #createRelative},
       * it makes a difference whether the specified resource base path here
       * ends with a slash or not. In the case of "C:/dir1/", relative paths
       * will be built underneath that root: e.g. relative path "dir2" &rarr;
       * "C:/dir1/dir2". In the case of "C:/dir1", relative paths will apply
       * at the same directory level: relative path "dir2" &rarr; "C:/dir2".
       *
       * @param path a file path
       * @see #FileSystemResource(Path)
       */
      public FileSystemResource(String path) {
          AbstractAssert.notNull(path, "Path must not be null");
          this.path = StringUtils.cleanPath(path);
          this.file = new File(path);
          this.filePath = this.file.toPath();
      }
  
      /**
       * Create a new {@code FileSystemResource} from a {@link File} handle.
       *
       * <p>Note: When building relative resources via {@link #createRelative},
       * the relative path will apply <i>at the same directory level</i>:
       * e.g. new File("C:/dir1"), relative path "dir2" &rarr; "C:/dir2"!
       * If you prefer to have relative paths built underneath the given root directory,
       * use the {@link #FileSystemResource(String) constructor with a file path}
       * to append a trailing slash to the root path: "C:/dir1/", which indicates
       * this directory as root for all relative paths.
       *
       * @param file a File handle
       * @see #FileSystemResource(Path)
       * @see #getFile()
       */
      public FileSystemResource(File file) {
          AbstractAssert.notNull(file, "File must not be null");
          this.path = StringUtils.cleanPath(file.getPath());
          this.file = file;
          this.filePath = file.toPath();
      }
  
      /**
       * Create a new {@code FileSystemResource} from a {@link Path} handle,
       * performing all file system interactions via NIO.2 instead of {@link File}.
       *
       *  <p>In contrast to {@link PathResource}, this variant strictly follows the
       * general {@link FileSystemResource} conventions, in particular in terms of
       * path cleaning and {@link #createRelative(String)} handling.
       *
       * <p>Note: When building relative resources via {@link #createRelative},
       * the relative path will apply <i>at the same directory level</i>:
       * e.g. Paths.get("C:/dir1"), relative path "dir2" &rarr; "C:/dir2"!
       * If you prefer to have relative paths built underneath the given root directory,
       * use the {@link #FileSystemResource(String) constructor with a file path}
       * to append a trailing slash to the root path: "C:/dir1/", which indicates
       * this directory as root for all relative paths. Alternatively, consider
       * using {@link PathResource#PathResource(Path)} for {@code java.nio.path.Path}
       * resolution in {@code createRelative}, always nesting relative paths.
       *
       * @param filePath a Path handle to a file
       * @see #FileSystemResource(File)
       * @since 5.1
       */
      public FileSystemResource(Path filePath) {
          AbstractAssert.notNull(filePath, "Path must not be null");
          this.path = StringUtils.cleanPath(filePath.toString());
          this.file = null;
          this.filePath = filePath;
      }
  
      /**
       * Create a new {@code FileSystemResource} from a {@link FileSystem} handle,
       * locating the specified path.
       *
       * <p>This is an alternative to {@link #FileSystemResource(String)},
       * performing all file system interactions via NIO.2 instead of {@link File}.
       *
       * @param fileSystem the FileSystem to locate the path within
       * @param path       a file path
       * @see #FileSystemResource(File)
       * @since 5.1.1
       */
      public FileSystemResource(FileSystem fileSystem, String path) {
          AbstractAssert.notNull(fileSystem, "FileSystem must not be null");
          AbstractAssert.notNull(path, "Path must not be null");
          this.path = StringUtils.cleanPath(path);
          this.file = null;
          this.filePath = fileSystem.getPath(this.path).normalize();
      }
  
      /**
       * Return the file path for this resource.
       */
      public final String getPath() {
          return this.path;
      }
  
      /**
       * This implementation returns whether the underlying file exists.
       *
       * @see File#exists()
       */
      @Override
      public boolean exists() {
          return (this.file != null ? this.file.exists() : Files.exists(this.filePath));
      }
  
      /**
       * This implementation checks whether the underlying file is marked as readable
       * (and corresponds to an actual file with content, not to a directory).
       *
       * @see File#canRead()
       * @see File#isDirectory()
       */
      @Override
      public boolean isReadable() {
          return (this.file != null ? this.file.canRead() && !this.file.isDirectory() :
                  Files.isReadable(this.filePath) && !Files.isDirectory(this.filePath));
      }
  
      /**
       * This implementation opens a NIO file stream for the underlying file.
       *
       * @see java.io.FileInputStream
       */
      @Override
      public InputStream getInputStream() throws IOException {
          try {
              return Files.newInputStream(this.filePath);
          } catch (NoSuchFileException ex) {
              throw new FileNotFoundException(ex.getMessage());
          }
      }
  
      /**
       * This implementation checks whether the underlying file is marked as writable
       * (and corresponds to an actual file with content, not to a directory).
       *
       * @see File#canWrite()
       * @see File#isDirectory()
       */
      @Override
      public boolean isWritable() {
          return (this.file != null ? this.file.canWrite() && !this.file.isDirectory() :
                  Files.isWritable(this.filePath) && !Files.isDirectory(this.filePath));
      }
  
      /**
       * This implementation opens a FileOutputStream for the underlying file.
       *
       * @see java.io.FileOutputStream
       */
      @Override
      public OutputStream getOutputStream() throws IOException {
          return Files.newOutputStream(this.filePath);
      }
  
      /**
       * This implementation returns a URL for the underlying file.
       *
       * @see File#toURI()
       */
      @Override
      public URL getUrl() throws IOException {
          return (this.file != null ? this.file.toURI().toURL() : this.filePath.toUri().toURL());
      }
  
      /**
       * This implementation returns a URI for the underlying file.
       *
       * @see File#toURI()
       */
      @Override
      public URI getUri() throws IOException {
          return (this.file != null ? this.file.toURI() : this.filePath.toUri());
      }
  
      /**
       * This implementation always indicates a file.
       */
      @Override
      public boolean isFile() {
          return true;
      }
  
      /**
       * This implementation returns the underlying File reference.
       */
      @Override
      public File getFile() {
          return (this.file != null ? this.file : this.filePath.toFile());
      }
  
      /**
       * This implementation opens a FileChannel for the underlying file.
       *
       * @see FileChannel
       */
      @Override
      public ReadableByteChannel readableChannel() throws IOException {
          try {
              return FileChannel.open(this.filePath, StandardOpenOption.READ);
          } catch (NoSuchFileException ex) {
              throw new FileNotFoundException(ex.getMessage());
          }
      }
  
      /**
       * This implementation opens a FileChannel for the underlying file.
       *
       * @see FileChannel
       */
      @Override
      public WritableByteChannel writableChannel() throws IOException {
          return FileChannel.open(this.filePath, StandardOpenOption.WRITE);
      }
  
      /**
       * This implementation returns the underlying File/Path length.
       */
      @Override
      public long contentLength() throws IOException {
          if (this.file != null) {
              long length = this.file.length();
              if (length == 0L && !this.file.exists()) {
                  throw new FileNotFoundException(getDescription()
                          + " cannot be resolved in the file system for checking its content length");
              }
              return length;
          } else {
              try {
                  return Files.size(this.filePath);
              } catch (NoSuchFileException ex) {
                  throw new FileNotFoundException(ex.getMessage());
              }
          }
      }
  
      /**
       * This implementation returns the underlying File/Path last-modified time.
       */
      @Override
      public long lastModified() throws IOException {
          if (this.file != null) {
              return super.lastModified();
          } else {
              try {
                  return Files.getLastModifiedTime(this.filePath).toMillis();
              } catch (NoSuchFileException ex) {
                  throw new FileNotFoundException(ex.getMessage());
              }
          }
      }
  
      /**
       * This implementation creates a FileSystemResource, applying the given path
       * relative to the path of the underlying file of this resource descriptor.
       *
       * @see StringUtils#applyRelativePath(String, String)
       */
      @Override
      public Resource createRelative(String relativePath) {
          String pathToUse = StringUtils.applyRelativePath(this.path, relativePath);
          return (this.file != null ? new FileSystemResource(pathToUse) :
                  new FileSystemResource(this.filePath.getFileSystem(), pathToUse));
      }
  
      /**
       * This implementation returns the name of the file.
       *
       * @see File#getName()
       */
      @Override
      public String getFilename() {
          return (this.file != null ? this.file.getName() : this.filePath.getFileName().toString());
      }
  
      /**
       * This implementation returns a description that includes the absolute
       * path of the file.
       *
       * @see File#getAbsolutePath()
       */
      @Override
      public String getDescription() {
          return "file [" + (this.file != null ? this.file.getAbsolutePath() : this.filePath.toAbsolutePath()) + "]";
      }
  
  
      /**
       * This implementation compares the underlying File references.
       */
      @Override
      public boolean equals(Object other) {
          return (this == other || (other instanceof FileSystemResource
                  && this.path.equals(((FileSystemResource) other).path)));
      }
  
      /**
       * This implementation returns the hash code of the underlying File reference.
       */
      @Override
      public int hashCode() {
          return this.path.hashCode();
      }
  
  }
  