* NativeLibraryLoader: Add method to extract a platform's natives

jme3-desktop/src/main/java/com/jme3/system/NativeLibraryLoader.java

@@ -40,6 +40,7 @@ import java.net.MalformedURLException;
 import java.net.URL;
 import java.net.URLConnection;
 import java.util.HashMap;
+import java.util.Map;
 import java.util.logging.Level;
 import java.util.logging.Logger;
 
@@ -278,6 +279,106 @@ public final class NativeLibraryLoader {
             }
         }
     }
+    
+    public static void extractNativeLibraries(Platform platform, File targetDir) throws IOException {
+        for (Map.Entry<NativeLibrary.Key, NativeLibrary> lib : nativeLibraryMap.entrySet()) {
+            if (lib.getValue().getPlatform() == platform) {
+                if (!targetDir.exists()) {
+                    targetDir.mkdirs();
+                }
+                extractNativeLibrary(platform, lib.getValue().getName(), targetDir);
+            }
+        }
+    }
+    
+    private static String mapLibraryName_emulated(String name, Platform platform) {
+        switch (platform) {
+            case MacOSX32:
+            case MacOSX64:
+                return name + ".dylib";
+            case Windows32:
+            case Windows64:
+                return name + ".dll";
+            default:
+                return name + ".so";
+        }
+    }
+    
+    public static void extractNativeLibrary(Platform platform, String name, File extractionDir) throws IOException {
+        NativeLibrary library = nativeLibraryMap.get(new NativeLibrary.Key(name, platform));
+        if (library == null) {
+            return;
+        }
+
+        String pathInJar = library.getPathInNativesJar();
+        if (pathInJar == null) {
+            return;
+        }
+        
+        String fileNameInJar;
+        if (pathInJar.contains("/")) {
+            fileNameInJar = pathInJar.substring(pathInJar.lastIndexOf("/") + 1);
+        } else {
+            fileNameInJar = pathInJar;
+        }
+        
+        URL url = Thread.currentThread().getContextClassLoader().getResource(pathInJar);
+        if (url == null) {
+            url = Thread.currentThread().getContextClassLoader().getResource(fileNameInJar);
+        }
+        
+        if (url == null) {
+            return;
+        }
+        
+        String loadedAsFileName;
+        if (library.isJNI()) {
+            String fileNameInJarWithoutExtension 
+                    = fileNameInJar.substring(0, fileNameInJar.lastIndexOf("."));
+            
+            if (platform.is64Bit() && !fileNameInJarWithoutExtension.endsWith("64")) {
+                fileNameInJarWithoutExtension += "64";
+            }
+            
+            String systemJniExtension;
+            String dummyLib = mapLibraryName_emulated("", platform);
+            if (dummyLib.contains(".")) {
+                systemJniExtension = dummyLib.substring(dummyLib.lastIndexOf("."));
+            } else {
+                systemJniExtension = "";
+            }
+            
+            loadedAsFileName = fileNameInJarWithoutExtension + systemJniExtension;
+        } else {
+            loadedAsFileName = fileNameInJar;
+        }
+        
+        URLConnection conn = url.openConnection();
+        InputStream in = conn.getInputStream();
+        
+        File targetFile = new File(extractionDir, loadedAsFileName);
+        OutputStream out = null;
+        try {
+            out = new FileOutputStream(targetFile);
+            int len;
+            while ((len = in.read(buf)) > 0) {
+                out.write(buf, 0, len);
+            }
+        } finally {
+            if (in != null) {
+                try {
+                    in.close();
+                } catch (IOException ex) {
+                }
+            }
+            if (out != null) {
+                try {
+                    out.close();
+                } catch (IOException ex) {
+                }
+            }
+        }
+    }
 
     /**
      * First extracts the native library and then loads it.