FileObject.java

/*
 * Copyright (c) 2006, 2014, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
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 */

package javax.tools;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.Reader;
import java.io.Writer;
import java.net.URI;

/**
 * File abstraction for tools.  In this context, <em>file</em> means
 * an abstraction of regular files and other sources of data.  For
 * example, a file object can be used to represent regular files,
 * memory cache, or data in databases.
 *
 * <p>All methods in this interface might throw a SecurityException if
 * a security exception occurs.
 *
 * <p>Unless explicitly allowed, all methods in this interface might
 * throw a NullPointerException if given a {@code null} argument.
 *
 * @author Peter von der Ah&eacute;
 * @author Jonathan Gibbons
 * @since 1.6
 */
// 文件对象
public interface FileObject {
    
    /**
     * Returns an InputStream for this file object.
     *
     * @return an InputStream
     *
     * @throws IllegalStateException         if this file object was
     *                                       opened for writing and does not support reading
     * @throws UnsupportedOperationException if this kind of file
     *                                       object does not support byte access
     * @throws IOException                   if an I/O error occurred
     */
    // 打开输入流，准备读文件
    InputStream openInputStream() throws IOException;
    
    /**
     * Returns an OutputStream for this file object.
     *
     * @return an OutputStream
     *
     * @throws IllegalStateException         if this file object was
     *                                       opened for reading and does not support writing
     * @throws UnsupportedOperationException if this kind of
     *                                       file object does not support byte access
     * @throws IOException                   if an I/O error occurred
     */
    // 打开输出流，准备写文件
    OutputStream openOutputStream() throws IOException;
    
    /**
     * Returns a reader for this object.  The returned reader will
     * replace bytes that cannot be decoded with the default
     * translation character.  In addition, the reader may report a
     * diagnostic unless {@code ignoreEncodingErrors} is true.
     *
     * @param ignoreEncodingErrors ignore encoding errors if true
     *
     * @return a Reader
     *
     * @throws IllegalStateException         if this file object was
     *                                       opened for writing and does not support reading
     * @throws UnsupportedOperationException if this kind of
     *                                       file object does not support character access
     * @throws IOException                   if an I/O error occurred
     */
    // 打开字符输入流，准备读文件
    Reader openReader(boolean ignoreEncodingErrors) throws IOException;
    
    /**
     * Returns a Writer for this file object.
     *
     * @return a Writer
     *
     * @throws IllegalStateException         if this file object was
     *                                       opened for reading and does not support writing
     * @throws UnsupportedOperationException if this kind of
     *                                       file object does not support character access
     * @throws IOException                   if an I/O error occurred
     */
    // 打开字符输出流，准备写文件
    Writer openWriter() throws IOException;
    
    /**
     * Returns a URI identifying this file object.
     *
     * @return a URI
     */
    // 获取文件的UTI
    URI toUri();
    
    /**
     * Returns a user-friendly name for this file object.  The exact
     * value returned is not specified but implementations should take
     * care to preserve names as given by the user.  For example, if
     * the user writes the filename {@code "BobsApp\Test.java"} on
     * the command line, this method should return {@code
     * "BobsApp\Test.java"} whereas the {@linkplain #toUri toUri}
     * method might return {@code
     * file:///C:/Documents%20and%20Settings/UncleBob/BobsApp/Test.java}.
     *
     * @return a user-friendly name
     */
    // 获取文件名称（包括路径）
    String getName();
    
    /**
     * Returns the character content of this file object, if available.
     * Any byte that cannot be decoded will be replaced by the default
     * translation character.  In addition, a diagnostic may be
     * reported unless {@code ignoreEncodingErrors} is true.
     *
     * @param ignoreEncodingErrors ignore encoding errors if true
     *
     * @return a CharSequence if available; {@code null} otherwise
     *
     * @throws IllegalStateException         if this file object was
     *                                       opened for writing and does not support reading
     * @throws UnsupportedOperationException if this kind of
     *                                       file object does not support character access
     * @throws IOException                   if an I/O error occurred
     */
    // 获取文件内容（文件需以读模式打开）
    CharSequence getCharContent(boolean ignoreEncodingErrors) throws IOException;
    
    /**
     * Returns the time this file object was last modified.  The time is
     * measured in milliseconds since the epoch (00:00:00 GMT, January
     * 1, 1970).
     *
     * @return the time this file object was last modified; or 0 if
     * the file object does not exist, if an I/O error occurred, or if
     * the operation is not supported
     */
    // 返回文件最后一次修改的时间，返回0表示该文件不存在或存在I/O错误或不支持此操作
    long getLastModified();
    
    /**
     * Deletes this file object.  In case of errors, returns false.
     *
     * @return true if and only if this file object is successfully
     * deleted; false otherwise
     */
    // 尝试删除文件，返回值表示文件是否删除成功
    boolean delete();
    
}