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 

    26 package jdk.nashorn.api.scripting;

    27 

    28 import java.io.CharArrayReader;

    29 import java.io.IOException;

    30 import java.io.Reader;

    31 import java.net.URL;

    32 import java.nio.charset.Charset;

    33 import java.util.Objects;

    34 import 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 public 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 }