jurt/com/sun/star/lib/util/UrlToFileMapper.java

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  30 package com.sun.star.lib.util;
  31
  32 import java.io.File;
  33 import java.lang.reflect.Constructor;
  34 import java.lang.reflect.InvocationTargetException;
  35 import java.lang.reflect.Method;
  36 import java.net.URL;
  37 import java.net.URLDecoder;
  38 import java.net.URLEncoder;
  39
  40 /**
  41  * Maps Java URL representations to File representations, on any Java version.
  42  *
  43  * @since UDK 3.2.8
  44  */
  45 public final class UrlToFileMapper {
  46
  47     // java.net.URLEncoder.encode(String, String) and java.net.URI are only
  48     // available since Java 1.4:
  49     private static Method urlEncoderEncode;
  50     private static Constructor uriConstructor;
  51     private static Constructor fileConstructor;
  52     static {
  53         try {
  54             urlEncoderEncode = URLEncoder.class.getMethod(
  55                 "encode", new Class[] { String.class, String.class });
  56             Class uriClass = Class.forName("java.net.URI");
  57             uriConstructor = uriClass.getConstructor(
  58                 new Class[] { String.class });
  59             fileConstructor = File.class.getConstructor(
  60                 new Class[] { uriClass });
  61         } catch (ClassNotFoundException e) {
  62         } catch (NoSuchMethodException e) {
  63         }
  64     }
  65
  66     /**
  67      * Maps Java URL representations to File representations.
  68      *
  69      * @param url some URL, possibly null.
  70      * @return a corresponding File, or null on failure.
  71      */
  72     public static File mapUrlToFile(URL url) {
  73         if (url == null) {
  74             return null;
  75         } else if (fileConstructor == null) {
  76             // If java.net.URI is not available, hope that the following works
  77             // well:  First, check that the given URL has a certain form.
  78             // Second, use the URLDecoder to decode the URL path (taking care
  79             // not to change any plus signs to spaces), hoping that the used
  80             // default encoding is the proper one for file URLs.  Third, create
  81             // a File from the decoded path.
  82             return url.getProtocol().equalsIgnoreCase("file")
  83                 && url.getAuthority() == null && url.getQuery() == null
  84                 && url.getRef() == null
  85                 ? new File(URLDecoder.decode(
  86                                StringHelper.replace(url.getPath(), '+', "%2B")))
  87                 : null;
  88         } else {
  89             // If java.net.URI is avaliable, do
  90             //   URI uri = new URI(encodedUrl);
  91             //   try {
  92             //       return new File(uri);
  93             //   } catch (IllegalArgumentException e) {
  94             //       return null;
  95             //   }
  96             // where encodedUrl is url.toString(), but since that may contain
  97             // unsafe characters (e.g., space, " "), it is encoded, as otherwise
  98             // the URI constructor might throw java.net.URISyntaxException (in
  99             // Java 1.5, URL.toURI might be used instead).
 100             String encodedUrl = encode(url.toString());
 101             try {
 102                 Object uri = uriConstructor.newInstance(
 103                     new Object[] { encodedUrl });
 104                 try {
 105                     return (File) fileConstructor.newInstance(
 106                         new Object[] { uri });
 107                 } catch (InvocationTargetException e) {
 108                     if (e.getTargetException() instanceof
 109                         IllegalArgumentException) {
 110                         return null;
 111                     } else {
 112                         throw e;
 113                     }
 114                 }
 115             } catch (InstantiationException e) {
 116                 throw new RuntimeException("This cannot happen: " + e);
 117             } catch (IllegalAccessException e) {
 118                 throw new RuntimeException("This cannot happen: " + e);
 119             } catch (InvocationTargetException e) {
 120                 if (e.getTargetException() instanceof Error) {
 121                     throw (Error) e.getTargetException();
 122                 } else if (e.getTargetException() instanceof RuntimeException) {
 123                     throw (RuntimeException) e.getTargetException();
 124                 } else {
 125                     throw new RuntimeException("This cannot happen: " + e);
 126                 }
 127             }
 128         }
 129     }
 130
 131
 132
 133     private static String encode(String url) {
 134         StringBuffer buf = new StringBuffer();
 135         for (int i = 0; i < url.length(); ++i) {
 136             char c = url.charAt(i);
 137             // The RFC 2732 <uric> characters: !$&'()*+,-./:;=?@[]_~ plus digits
 138             // and letters; additionally, do not encode % again.
 139             if (c >= 'a' && c <= 'z' || c >= '?' && c <= '['
 140                 || c >= '$' && c <= ';' || c == '!' || c == '=' || c == ']'
 141                 || c == '_' || c == '~')
 142             {
 143                 buf.append(c);
 144             } else if (c == ' ') {
 145                 buf.append("%20");
 146             } else {
 147                 String enc;
 148                 try {
 149                     enc = (String) urlEncoderEncode.invoke(
 150                         null,
 151                         new Object[] { new Character(c).toString(), "UTF-8" });
 152                 } catch (IllegalAccessException e) {
 153                     throw new RuntimeException("This cannot happen: " + e);
 154                 } catch (InvocationTargetException e) {
 155                     throw new RuntimeException("This cannot happen: " + e);
 156                 }
 157                 buf.append(enc);
 158             }
 159         }
 160         return buf.toString();
 161     }
 162
 163     private UrlToFileMapper() {}
 164 }