如何將JAR檔案內容提取到指定目錄？

<code class="java">// JAR file to extract
java.util.jar.JarFile jar = new java.util.jar.JarFile(jarFile);

// Extract all entries
java.util.Enumeration enumEntries = jar.entries();
while (enumEntries.hasMoreElements()) {
    // Get the entry
    java.util.jar.JarEntry file = (java.util.jar.JarEntry) enumEntries.nextElement();

    // Create a file object
    java.io.File f = new java.io.File(destDir + java.io.File.separator + file.getName());

    // If the entry is a directory, create it
    if (file.isDirectory()) {
        f.mkdir();
        continue;
    }

    // Otherwise, extract the file
    java.io.InputStream is = jar.getInputStream(file); // Input stream
    java.io.FileOutputStream fos = new java.io.FileOutputStream(f); // Output stream

    // Write the file contents
    while (is.available() > 0) {
        fos.write(is.read());
    }

    // Close streams
    fos.close();
    is.close();
}

// Close the JAR file
jar.close();</code>