1 /*

     2  * Copyright (c) 2004, 2011, 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 sun.nio.cs;

    27 

    28 import java.nio.charset.Charset;

    29 import java.nio.charset.spi.CharsetProvider;

    30 import java.util.Iterator;

    31 import java.util.Map;

    32 

    33 

    34 /**

    35  * Abstract base class for fast charset providers.

    36  *

    37  * @author Mark Reinhold

    38  */

    39 

    40 public class FastCharsetProvider

    41     extends CharsetProvider

    42 {

    43 

    44     // Maps canonical names to class names

    45     private Map<String,String> classMap;

    46 

    47     // Maps alias names to canonical names

    48     private Map<String,String> aliasMap;

    49 

    50     // Maps canonical names to cached instances

    51     private Map<String,Charset> cache;

    52 

    53     private String packagePrefix;

    54 

    55     protected FastCharsetProvider(String pp,

    56                                   Map<String,String> am,

    57                                   Map<String,String> cm,

    58                                   Map<String,Charset> c)

    59     {

    60         packagePrefix = pp;

    61         aliasMap = am;

    62         classMap = cm;

    63         cache = c;

    64     }

    65 

    66     private String canonicalize(String csn) {

    67         String acn = aliasMap.get(csn);

    68         return (acn != null) ? acn : csn;

    69     }

    70 

    71     // Private ASCII-only version, optimized for interpretation during startup

    72     //

    73     private static String toLower(String s) {

    74         int n = s.length();

    75         boolean allLower = true;

    76         for (int i = 0; i < n; i++) {

    77             int c = s.charAt(i);

    78             if (((c - 'A') | ('Z' - c)) >= 0) {

    79                 allLower = false;

    80                 break;

    81             }

    82         }

    83         if (allLower)

    84             return s;

    85         char[] ca = new char[n];

    86         for (int i = 0; i < n; i++) {

    87             int c = s.charAt(i);

    88             if (((c - 'A') | ('Z' - c)) >= 0)

    89                 ca[i] = (char)(c + 0x20);

    90             else

    91                 ca[i] = (char)c;

    92         }

    93         return new String(ca);

    94     }

    95 

    96     private Charset lookup(String charsetName) {

    97 

    98         String csn = canonicalize(toLower(charsetName));

    99 

   100         // Check cache first

   101         Charset cs = cache.get(csn);

   102         if (cs != null)

   103             return cs;

   104 

   105         // Do we even support this charset?

   106         String cln = classMap.get(csn);

   107         if (cln == null)

   108             return null;

   109 

   110         if (cln.equals("US_ASCII")) {

   111             cs = new US_ASCII();

   112             cache.put(csn, cs);

   113             return cs;

   114         }

   115 

   116         // Instantiate the charset and cache it

   117         try {

   118             @SuppressWarnings("deprecation")

   119             Object o= Class.forName(packagePrefix + "." + cln,

   120                                     true,

   121                                     this.getClass().getClassLoader()).newInstance();

   122             cs = (Charset)o;

   123             cache.put(csn, cs);

   124             return cs;

   125         } catch (ClassNotFoundException |

   126                  IllegalAccessException |

   127                  InstantiationException x) {

   128             return null;

   129         }

   130     }

   131 

   132     public final Charset charsetForName(String charsetName) {

   133         synchronized (this) {

   134             return lookup(canonicalize(charsetName));

   135         }

   136     }

   137 

   138     public final Iterator<Charset> charsets() {

   139 

   140         return new Iterator<Charset>() {

   141 

   142                 Iterator<String> i = classMap.keySet().iterator();

   143 

   144                 public boolean hasNext() {

   145                     return i.hasNext();

   146                 }

   147 

   148                 public Charset next() {

   149                     String csn = i.next();

   150                     return lookup(csn);

   151                 }

   152 

   153                 public void remove() {

   154                     throw new UnsupportedOperationException();

   155                 }

   156 

   157             };

   158 

   159     }

   160 

   161 }