SmartWriter.java revision 2571:10fc81ac75b4 
1/*
2 * Copyright (c) 2012, 2013, 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 */
25package com.sun.tools.sjavac.comp;
26
27import java.io.*;
28import 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 */
41public 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}
79