1 /*

     2  * Copyright (c) 2012, Oracle and/or its affiliates. All rights reserved.

     3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.

     4  *

     5  * This code is free software; you can redistribute it and/or modify it

     6  * under the terms of the GNU General Public License version 2 only, as

     7  * published by the Free Software Foundation.  Oracle designates this

     8  * particular file as subject to the "Classpath" exception as provided

     9  * by Oracle in the LICENSE file that accompanied this code.

    10  *

    11  * This code is distributed in the hope that it will be useful, but WITHOUT

    12  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or

    13  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License

    14  * version 2 for more details (a copy is included in the LICENSE file that

    15  * accompanied this code).

    16  *

    17  * You should have received a copy of the GNU General Public License version

    18  * 2 along with this work; if not, write to the Free Software Foundation,

    19  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.

    20  *

    21  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA

    22  * or visit www.oracle.com if you need additional information or have any

    23  * questions.

    24  */

    25 package com.sun.tools.sjavac.comp;

    26 

    27 import java.io.*;

    28 import javax.tools.JavaFileObject;

    29 

    30 /**

    31  * The SmartWriter will cache the written data and when the writer is closed,

    32  * then it will compare the cached data with the old_content string.

    33  * If different, then it will write all the new content to the file.

    34  * If not, the file is not touched.

    35  *

    36  *  <p><b>This is NOT part of any supported API.

    37  * If you write code that depends on this, you do so at your own

    38  * risk.  This code and its internal interfaces are subject to change

    39  * or deletion without notice.</b></p>

    40  */

    41 public class SmartWriter extends Writer {

    42 

    43     String name;

    44     JavaFileObject file;

    45     String oldContent;

    46     StringWriter newContent = new StringWriter();

    47     PrintWriter stdout;

    48     boolean closed;

    49     public SmartWriter(JavaFileObject f, String s, String n, PrintWriter pw) {

    50         name = n;

    51         file = f;

    52         oldContent = s;

    53         newContent = new StringWriter();

    54         stdout = pw;

    55         closed = false;

    56     }

    57 

    58     public void write(char[] chars, int i, int i1)

    59     {

    60         newContent.write(chars, i, i1);

    61     }

    62 

    63     public void close() throws IOException {

    64         if (closed) return;

    65         closed = true;

    66         String s = newContent.toString();

    67         if (!oldContent.equals(s)) {

    68             int p = file.getName().lastIndexOf(File.separatorChar);

    69             try (Writer writer = file.openWriter()) {

    70                 writer.write(s);

    71             }

    72             stdout.println("Writing "+file.getName().substring(p+1));

    73         }

    74     }

    75 

    76     public void flush() throws IOException {

    77     }

    78 }