Extracted the strategy for finding native library out of Native.

src/main/java/net/rubygrapefruit/platform/internal/NativeLibraryLocator.java

@@ -0,0 +1,63 @@
+package net.rubygrapefruit.platform.internal;
+
+import net.rubygrapefruit.platform.NativeException;
+
+import java.io.*;
+import java.net.URL;
+
+public class NativeLibraryLocator {
+    private final File extractDir;
+
+    public NativeLibraryLocator(File extractDir) {
+        this.extractDir = extractDir;
+    }
+
+    public File find(String libraryName) throws IOException {
+        File libFile;
+        URL resource = getClass().getClassLoader().getResource(libraryName);
+        if (resource != null) {
+            File libDir = extractDir;
+            if (libDir == null) {
+                libDir = File.createTempFile("native-platform", "dir");
+                libDir.delete();
+                libDir.mkdirs();
+            }
+            libFile = new File(libDir, libraryName);
+            libFile.deleteOnExit();
+            copy(resource, libFile);
+            return libFile;
+        }
+
+        libFile = new File("build/binaries/" + libraryName);
+        if (libFile.isFile()) {
+            return libFile;
+        }
+
+        return null;
+    }
+
+    private static void copy(URL source, File dest) {
+        try {
+            InputStream inputStream = source.openStream();
+            try {
+                OutputStream outputStream = new FileOutputStream(dest);
+                try {
+                    byte[] buffer = new byte[4096];
+                    while (true) {
+                        int nread = inputStream.read(buffer);
+                        if (nread < 0) {
+                            break;
+                        }
+                        outputStream.write(buffer, 0, nread);
+                    }
+                } finally {
+                    outputStream.close();
+                }
+            } finally {
+                inputStream.close();
+            }
+        } catch (IOException e) {
+            throw new NativeException(String.format("Could not extract native JNI library."), e);
+        }
+    }
+}