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 jdk.nashorn.internal.runtime.Source;
  34 
  35 /**
  36  * A Reader that reads from a URL. Used to make sure that the reader
  37  * reads content from given URL and can be trusted to do so.
  38  *
  39  * @since 1.8u40
  40  */
  41 @jdk.Exported
  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         // null check
  81         url.getClass();
  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 }