| /* Licensed to the Apache Software Foundation (ASF) under one or more |
| * contributor license agreements. See the NOTICE file distributed with |
| * this work for additional information regarding copyright ownership. |
| * The ASF licenses this file to You 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 java.io; |
| |
| import java.util.Formatter; |
| |
| /** |
| * Provides access to the console, if available. The system-wide instance can |
| * be accessed via {@link java.lang.System#console}. |
| * @since 1.6 |
| */ |
| public final class Console implements Flushable { |
| private static final Object CONSOLE_LOCK = new Object(); |
| |
| private static final Console console = makeConsole(); |
| private static native boolean isatty(int fd); |
| |
| private final ConsoleReader reader; |
| private final PrintWriter writer; |
| |
| /** |
| * Secret accessor for {@code System.console}. |
| * @hide |
| */ |
| public static Console getConsole() { |
| return console; |
| } |
| |
| private static Console makeConsole() { |
| if (!isatty(0) || !isatty(1)) { |
| return null; |
| } |
| try { |
| return new Console(); |
| } catch (IOException ex) { |
| throw new AssertionError(ex); |
| } |
| } |
| |
| private Console() throws IOException { |
| this.reader = new ConsoleReader(System.in); |
| this.writer = new ConsoleWriter(System.out); |
| } |
| |
| public void flush() { |
| writer.flush(); |
| } |
| |
| /** |
| * Writes a formatted string to the console using |
| * the specified format string and arguments. |
| * |
| * @param format the format string (see {@link java.util.Formatter#format}) |
| * @param args |
| * the list of arguments passed to the formatter. If there are |
| * more arguments than required by {@code format}, |
| * additional arguments are ignored. |
| * @return the console instance. |
| */ |
| public Console format(String format, Object... args) { |
| Formatter f = new Formatter(writer); |
| f.format(format, args); |
| f.flush(); |
| return this; |
| } |
| |
| /** |
| * Equivalent to {@code format(format, args)}. |
| */ |
| public Console printf(String format, Object... args) { |
| return format(format, args); |
| } |
| |
| /** |
| * Returns the {@link Reader} associated with this console. |
| */ |
| public Reader reader() { |
| return reader; |
| } |
| |
| /** |
| * Reads a line from the console. |
| * |
| * @return the line, or null at EOF. |
| */ |
| public String readLine() { |
| try { |
| return reader.readLine(); |
| } catch (IOException e) { |
| throw new IOError(e); |
| } |
| } |
| |
| /** |
| * Reads a line from this console, using the specified prompt. |
| * The prompt is given as a format string and optional arguments. |
| * Note that this can be a source of errors: if it is possible that your |
| * prompt contains {@code %} characters, you must use the format string {@code "%s"} |
| * and pass the actual prompt as a parameter. |
| * |
| * @param format the format string (see {@link java.util.Formatter#format}) |
| * @param args |
| * the list of arguments passed to the formatter. If there are |
| * more arguments than required by {@code format}, |
| * additional arguments are ignored. |
| * @return the line, or null at EOF. |
| */ |
| public String readLine(String format, Object... args) { |
| synchronized (CONSOLE_LOCK) { |
| format(format, args); |
| return readLine(); |
| } |
| } |
| |
| /** |
| * Reads a password from the console. The password will not be echoed to the display. |
| * |
| * @return a character array containing the password, or null at EOF. |
| */ |
| public char[] readPassword() { |
| synchronized (CONSOLE_LOCK) { |
| int previousState = setEcho(false, 0); |
| try { |
| String password = readLine(); |
| writer.println(); // We won't have echoed the user's newline. |
| return (password == null) ? null : password.toCharArray(); |
| } finally { |
| setEcho(true, previousState); |
| } |
| } |
| } |
| |
| private static int setEcho(boolean on, int previousState) { |
| try { |
| return setEchoImpl(on, previousState); |
| } catch (IOException ex) { |
| throw new IOError(ex); |
| } |
| } |
| private static native int setEchoImpl(boolean on, int previousState) throws IOException; |
| |
| /** |
| * Reads a password from the console. The password will not be echoed to the display. |
| * A formatted prompt is also displayed. |
| * |
| * @param format the format string (see {@link java.util.Formatter#format}) |
| * @param args |
| * the list of arguments passed to the formatter. If there are |
| * more arguments than required by {@code format}, |
| * additional arguments are ignored. |
| * @return a character array containing the password, or null at EOF. |
| */ |
| public char[] readPassword(String format, Object... args) { |
| synchronized (CONSOLE_LOCK) { |
| format(format, args); |
| return readPassword(); |
| } |
| } |
| |
| /** |
| * Returns the {@link Writer} associated with this console. |
| */ |
| public PrintWriter writer() { |
| return writer; |
| } |
| |
| private static class ConsoleReader extends BufferedReader { |
| public ConsoleReader(InputStream in) throws IOException { |
| super(new InputStreamReader(in, System.getProperty("file.encoding")), 256); |
| lock = CONSOLE_LOCK; |
| } |
| |
| @Override |
| public void close() { |
| // Console.reader cannot be closed. |
| } |
| } |
| |
| private static class ConsoleWriter extends PrintWriter { |
| public ConsoleWriter(OutputStream out) { |
| super(out, true); |
| lock = CONSOLE_LOCK; |
| } |
| |
| @Override |
| public void close() { |
| // Console.writer cannot be closed. |
| flush(); |
| } |
| } |
| } |