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21 
22 
23 package com.sun.star.lib.util;
24 
25 import java.io.File;
26 import java.net.URL;
27 import java.net.URLClassLoader;
28 
29 /** Helper functions to locate and load native files.
30 
31     The methods in this class are designed to find the requested resources in as
32     many cases as possible.  They search various places, roughly from most
33     specific to most general.  This works well if a component is known to bring
34     with it a certain resource, and that resource has to be found.  However, it
35     might not work very well in cases where you want to check whether a
36     component brings with it a certain resource or not: a similarly named
37     resource from another component might be found by the eager search
38     algorithm.
39  */
40 public final class NativeLibraryLoader {
41     /** Load a system library, using a given class loader to locate the library.
42 
43         This is similar to System.loadLibrary.
44 
45         @param loader a class loader; may be null
46 
47         @param libname the library name; how this name is mapped to a system
48         library name is system dependent
49      */
loadLibrary(ClassLoader loader, String libname)50     public static void loadLibrary(ClassLoader loader, String libname) {
51         String syslibname = System.mapLibraryName(libname);
52 
53         File path = getResource(loader, System.mapLibraryName(libname));
54         if (path == null) {
55             // check special jni lib extension on Mac
56             if (syslibname.contains("dylib")) {
57                 syslibname = syslibname.replace("dylib", "jnilib");
58             }
59             path = getResource(loader, syslibname);
60         }
61 
62         if (path == null) {
63             // If the library cannot be found as a class loader resource, try
64             // the global System.loadLibrary as a last resort:
65             System.loadLibrary(libname);
66         } else {
67             System.load(path.getAbsolutePath());
68         }
69     }
70 
71     /** Locate a system resource, using a given class loader.
72 
73         This is similar to ClassLoader.getResource, but only works for local
74         resources (local files), and adds additional functionality for
75         URLClassLoaders.
76 
77         @param loader a class loader; may be null
78 
79         @param name a resource name (that is, the name of a file)
80 
81         @return a File locating the resource, or null if the resource was not
82         found
83      */
getResource(ClassLoader loader, String name)84     public static File getResource(ClassLoader loader, String name) {
85         if (loader != null) {
86             File path = UrlToFileMapper.mapUrlToFile(loader.getResource(name));
87             if (path != null) {
88                 return path;
89             }
90         }
91         // URLClassLoaders work on lists of URLs, which are typically URLs
92         // locating JAR files (scheme://auth/dir1/dir2/some.jar).  The following
93         // code looks for resource name beside the JAR file
94         // (scheme://auth/dir1/dir2/name) and one directory up
95         // (scheme://auth/dir1/name).  The second step is important in a typical
96         // OOo installation, where the JAR files are in the program/classes
97         // directory while the shared libraries are in the program directory.
98         if (loader instanceof URLClassLoader) {
99             URL[] urls = ((URLClassLoader) loader).getURLs();
100             for (int i = 0; i < urls.length; ++i) {
101                 File path = UrlToFileMapper.mapUrlToFile(urls[i]);
102                 if (path != null) {
103                     File dir = path.isDirectory() ? path : path.getParentFile();
104                     if (dir != null) {
105                         path = new File(dir, name);
106                         if (path.exists()) {
107                             return path;
108                         }
109                         dir = dir.getParentFile();
110                         if (dir != null) {
111                             path = new File(dir, name);
112                             if (path.exists()) {
113                                 return path;
114                             }
115                         }
116                     }
117                 }
118             }
119         }
120         return null;
121     }
122 
NativeLibraryLoader()123     private NativeLibraryLoader() {} // do not instantiate
124 }
125