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

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   9  * $RCSfile: NativeLibraryLoader.java,v $
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  30 package com.sun.star.lib.util;
  31
  32 import java.io.File;
  33 import java.net.URL;
  34 import java.net.URLClassLoader;
  35
  36 /** Helper functions to locate and load native files.
  37
  38     The methods in this class are designed to find the requested resources in as
  39     many cases as possible.  They search various places, roughly from most
  40     specific to most general.  This works well if a component is known to bring
  41     with it a certain resource, and that resource has to be found.  However, it
  42     might not work very well in cases where you want to check whether a
  43     component brings with it a certain resource or not: a similarly named
  44     resource from another component might be found by the eager search
  45     algorithm.
  46  */
  47 public final class NativeLibraryLoader {
  48     /** Load a system library, using a given class loader to locate the library.
  49
  50         This is similar to System.loadLibrary.
  51
  52         @param loader a class loader; may be null
  53
  54         @param libname the library name; how this name is mapped to a system
  55         library name is system dependent
  56      */
  57     public static void loadLibrary(ClassLoader loader, String libname) {
  58         File path = getResource(loader, System.mapLibraryName(libname));
  59         if (path == null) {
  60             // If the library cannot be found as a class loader resource, try
  61             // the global System.loadLibrary as a last resort:
  62             System.loadLibrary(libname);
  63         } else {
  64             System.load(path.getAbsolutePath());
  65         }
  66     }
  67
  68     /** Locate a system resource, using a given class loader.
  69
  70         This is similar to ClassLoader.getResource, but only works for local
  71         resources (local files), and adds additional functionality for
  72         URLClassLoaders.
  73
  74         @param loader a class loader; may be null
  75
  76         @param name a resource name (that is, the name of a file)
  77
  78         @return a File locating the resource, or null if the resource was not
  79         found
  80      */
  81     public static File getResource(ClassLoader loader, String name) {
  82         if (loader != null) {
  83             File path = UrlToFileMapper.mapUrlToFile(loader.getResource(name));
  84             if (path != null) {
  85                 return path;
  86             }
  87         }
  88         // URLClassLoaders work on lists of URLs, which are typically URLs
  89         // locating JAR files (scheme://auth/dir1/dir2/some.jar).  The following
  90         // code looks for resource name beside the JAR file
  91         // (scheme://auth/dir1/dir2/name) and one directory up
  92         // (scheme://auth/dir1/name).  The second step is important in a typical
  93         // OOo installation, where the JAR files are in the program/classes
  94         // directory while the shared libraries are in the program directory.
  95         if (loader instanceof URLClassLoader) {
  96             URL[] urls = ((URLClassLoader) loader).getURLs();
  97             for (int i = 0; i < urls.length; ++i) {
  98                 File path = UrlToFileMapper.mapUrlToFile(urls[i]);
  99                 if (path != null) {
 100                     File dir = path.isDirectory() ? path : path.getParentFile();
 101                     if (dir != null) {
 102                         path = new File(dir, name);
 103                         if (path.exists()) {
 104                             return path;
 105                         }
 106                         dir = dir.getParentFile();
 107                         if (dir != null) {
 108                             path = new File(dir, name);
 109                             if (path.exists()) {
 110                                 return path;
 111                             }
 112                         }
 113                     }
 114                 }
 115             }
 116         }
 117         return null;
 118     }
 119
 120     private NativeLibraryLoader() {} // do not instantiate
 121 }