URLReader.java revision 1177:8e86c58cbb00 
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 */
42@jdk.Exported
43public final class URLReader extends Reader {
44    // underlying URL
45    private final URL url;
46    // Charset used to convert
47    private final Charset cs;
48
49    // lazily initialized underlying reader for URL
50    private Reader reader;
51
52    /**
53     * Constructor
54     *
55     * @param url URL for this URLReader
56     * @throws NullPointerException if url is null
57     */
58    public URLReader(final URL url) {
59        this(url, (Charset)null);
60    }
61
62    /**
63     * Constructor
64     *
65     * @param url URL for this URLReader
66     * @param charsetName  Name of the Charset used to convert bytes to chars
67     * @throws NullPointerException if url is null
68     */
69    public URLReader(final URL url, final String charsetName) {
70        this(url, Charset.forName(charsetName));
71    }
72
73    /**
74     * Constructor
75     *
76     * @param url URL for this URLReader
77     * @param cs  Charset used to convert bytes to chars
78     * @throws NullPointerException if url is null
79     */
80    public URLReader(final URL url, final Charset cs) {
81        Objects.requireNonNull(url);
82        this.url = url;
83        this.cs  = cs;
84    }
85
86    @Override
87    public int read(final char cbuf[], final int off, final int len) throws IOException {
88        return getReader().read(cbuf, off, len);
89    }
90
91    @Override
92    public void close() throws IOException {
93        getReader().close();
94    }
95
96    /**
97     * URL of this reader
98     * @return the URL from which this reader reads.
99     */
100    public URL getURL() {
101        return url;
102    }
103
104    /**
105     * Charset used by this reader
106     *
107     * @return the Chartset used to convert bytes to chars
108     */
109    public Charset getCharset() {
110        return cs;
111    }
112
113    // lazily initialize char array reader using URL content
114    private Reader getReader() throws IOException {
115        synchronized (lock) {
116            if (reader == null) {
117                reader = new CharArrayReader(Source.readFully(url, cs));
118            }
119        }
120
121        return reader;
122    }
123}
124