content: /*
   * Copyright 2013-2023 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.cloud.commons.io;
  
  import java.io.File;
  import java.io.FileInputStream;
  import java.io.FileNotFoundException;
  import java.io.IOException;
  import java.io.InputStream;
  import java.nio.charset.Charset;
  
  /**
   * FileUtils. copy from apache commons-io.
   *
   * @author <a href="mailto:chenxilzx1@gmail.com">theonefx</a>
   */
  public final class FileUtils {
  
  	private FileUtils() {
  	}
  
  	// -----------------------------------------------------------------------
  	/**
  	 * Opens a {@link java.io.FileInputStream} for the specified file, providing better
  	 * error messages than simply calling <code>new FileInputStream(file)</code>.
  	 * <p>
  	 * At the end of the method either the stream will be successfully opened, or an
  	 * exception will have been thrown.
  	 * <p>
  	 * An exception is thrown if the file does not exist. An exception is thrown if the
  	 * file object exists but is a directory. An exception is thrown if the file exists
  	 * but cannot be read.
  	 * @param file the file to open for input, must not be {@code null}
  	 * @return a new {@link java.io.FileInputStream} for the specified file
  	 * @throws java.io.FileNotFoundException if the file does not exist
  	 * @throws IOException if the file object is a directory
  	 * @throws IOException if the file cannot be read
  	 * @since 1.3
  	 */
  	public static FileInputStream openInputStream(final File file) throws IOException {
  		if (file.exists()) {
  			if (file.isDirectory()) {
  				throw new IOException("File '" + file + "' exists but is a directory");
  			}
  			if (!file.canRead()) {
  				throw new IOException("File '" + file + "' cannot be read");
  			}
  		}
  		else {
  			throw new FileNotFoundException("File '" + file + "' does not exist");
  		}
  		return new FileInputStream(file);
  	}
  
  	// -----------------------------------------------------------------------
  	/**
  	 * Reads the contents of a file into a String. The file is always closed.
  	 * @param file the file to read, must not be {@code null}
  	 * @param encoding the encoding to use, {@code null} means platform default
  	 * @return the file contents, never {@code null}
  	 * @throws IOException in case of an I/O error
  	 */
  	public static String readFileToString(final File file, final Charset encoding)
  			throws IOException {
  		try (InputStream in = openInputStream(file)) {
  			return IOUtils.toString(in, Charsets.toCharset(encoding));
  		}
  	}
  
  	/**
  	 * Reads the contents of a file into a String. The file is always closed.
  	 * @param file the file to read, must not be {@code null}
  	 * @param encoding the encoding to use, {@code null} means platform default
  	 * @return the file contents, never {@code null}
  	 * @throws java.io.IOException in case of an I/O error
  	 * @throws java.nio.charset.UnsupportedCharsetException thrown instead of
  	 * {@link java.io .UnsupportedEncodingException} in version 2.2 if the encoding is not
  	 * supported.
  	 */
  	public static String readFileToString(final File file, final String encoding)
  			throws IOException {
  		return readFileToString(file, Charsets.toCharset(encoding));
  	}
  
  	/**
  	 * Reads the contents of a file into a String using the default encoding for the VM.
  	 * The file is always closed.
  	 * @param file the file to read, must not be {@code null}
  	 * @return the file contents, never {@code null}
  	 * @throws IOException in case of an I/O error
  	 * @deprecated 2.5 use {@link #readFileToString(File, String)} instead (and specify
  	 * the appropriate encoding)
  	 */
  	@Deprecated
  	public static String readFileToString(final File file) throws IOException {
  		return readFileToString(file, Charset.defaultCharset());
  	}
  
  }
  