1 files changed, 93 insertions, 0 deletions
diff --git a/java/src/com/zerotier/sdk/NativeUtils.java b/java/src/com/zerotier/sdk/NativeUtils.java
new file mode 100644
index 00000000..07e1ef5b
--- /dev/null
+++ b/java/src/com/zerotier/sdk/NativeUtils.java
@@ -0,0 +1,93 @@
+package com.zerotier.sdk;
+
+import java.io.File;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.OutputStream;
+ 
+/**
+ * Simple library class for working with JNI (Java Native Interface)
+ * 
+ * @see http://adamheinrich.com/2012/how-to-load-native-jni-library-from-jar
+ *
+ * @author Adam Heirnich <adam@adamh.cz>, http://www.adamh.cz
+ */
+public class NativeUtils {
+ 
+    /**
+     * Private constructor - this class will never be instanced
+     */
+    private NativeUtils() {
+    }
+ 
+    /**
+     * Loads library from current JAR archive
+     * 
+     * The file from JAR is copied into system temporary directory and then loaded. The temporary file is deleted after exiting.
+     * Method uses String as filename because the pathname is "abstract", not system-dependent.
+     * 
+     * @param filename The filename inside JAR as absolute path (beginning with '/'), e.g. /package/File.ext
+     * @throws IOException If temporary file creation or read/write operation fails
+     * @throws IllegalArgumentException If source file (param path) does not exist
+     * @throws IllegalArgumentException If the path is not absolute or if the filename is shorter than three characters (restriction of {@see File#createTempFile(java.lang.String, java.lang.String)}).
+     */
+    public static void loadLibraryFromJar(String path) throws IOException {
+ 
+        if (!path.startsWith("/")) {
+            throw new IllegalArgumentException("The path has to be absolute (start with '/').");
+        }
+ 
+        // Obtain filename from path
+        String[] parts = path.split("/");
+        String filename = (parts.length > 1) ? parts[parts.length - 1] : null;
+ 
+        // Split filename to prexif and suffix (extension)
+        String prefix = "";
+        String suffix = null;
+        if (filename != null) {
+            parts = filename.split("\\.", 2);
+            prefix = parts[0];
+            suffix = (parts.length > 1) ? "."+parts[parts.length - 1] : null; // Thanks, davs! :-)
+        }
+ 
+        // Check if the filename is okay
+        if (filename == null || prefix.length() < 3) {
+            throw new IllegalArgumentException("The filename has to be at least 3 characters long.");
+        }
+ 
+        // Prepare temporary file
+        File temp = File.createTempFile(prefix, suffix);
+        temp.deleteOnExit();
+ 
+        if (!temp.exists()) {
+            throw new FileNotFoundException("File " + temp.getAbsolutePath() + " does not exist.");
+        }
+ 
+        // Prepare buffer for data copying
+        byte[] buffer = new byte[1024];
+        int readBytes;
+ 
+        // Open and check input stream
+        InputStream is = NativeUtils.class.getResourceAsStream(path);
+        if (is == null) {
+            throw new FileNotFoundException("File " + path + " was not found inside JAR.");
+        }
+ 
+        // Open output stream and copy data between source file in JAR and the temporary file
+        OutputStream os = new FileOutputStream(temp);
+        try {
+            while ((readBytes = is.read(buffer)) != -1) {
+                os.write(buffer, 0, readBytes);
+            }
+        } finally {
+            // If read/write fails, close streams safely before throwing an exception
+            os.close();
+            is.close();
+        }
+ 
+        // Finally, load the library
+        System.load(temp.getAbsolutePath());
+    }
+}
+\ No newline at end of file