URLReader.java revision 1590:1916a2c680d8 
1/*
2 * Copyright (c) 2010, 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 */
25
26package jdk.nashorn.api.scripting;
27
28import java.io.CharArrayReader;
29import java.io.IOException;
30import java.io.Reader;
31import java.net.URL;
32import java.nio.charset.Charset;
33import java.util.Objects;
34import jdk.nashorn.internal.runtime.Source;
35
36/**
37 * A Reader that reads from a URL. Used to make sure that the reader
38 * reads content from given URL and can be trusted to do so.
39 *
40 * @since 1.8u40
41 */
42public final class URLReader extends Reader {
43    // underlying URL
44    private final URL url;
45    // Charset used to convert
46    private final Charset cs;
47
48    // lazily initialized underlying reader for URL
49    private Reader reader;
50
51    /**
52     * Constructor
53     *
54     * @param url URL for this URLReader
55     * @throws NullPointerException if url is null
56     */
57    public URLReader(final URL url) {
58        this(url, (Charset)null);
59    }
60
61    /**
62     * Constructor
63     *
64     * @param url URL for this URLReader
65     * @param charsetName  Name of the Charset used to convert bytes to chars
66     * @throws NullPointerException if url is null
67     */
68    public URLReader(final URL url, final String charsetName) {
69        this(url, Charset.forName(charsetName));
70    }
71
72    /**
73     * Constructor
74     *
75     * @param url URL for this URLReader
76     * @param cs  Charset used to convert bytes to chars
77     * @throws NullPointerException if url is null
78     */
79    public URLReader(final URL url, final Charset cs) {
80        this.url = Objects.requireNonNull(url);
81        this.cs  = cs;
82    }
83
84    @Override
85    public int read(final char cbuf[], final int off, final int len) throws IOException {
86        return getReader().read(cbuf, off, len);
87    }
88
89    @Override
90    public void close() throws IOException {
91        getReader().close();
92    }
93
94    /**
95     * URL of this reader
96     * @return the URL from which this reader reads.
97     */
98    public URL getURL() {
99        return url;
100    }
101
102    /**
103     * Charset used by this reader
104     *
105     * @return the Charset used to convert bytes to chars
106     */
107    public Charset getCharset() {
108        return cs;
109    }
110
111    // lazily initialize char array reader using URL content
112    private Reader getReader() throws IOException {
113        synchronized (lock) {
114            if (reader == null) {
115                reader = new CharArrayReader(Source.readFully(url, cs));
116            }
117        }
118
119        return reader;
120    }
121}
122