How Can I Package DLLs with a Third-Party JAR File for Use in a Java Application?

Packaging DLLs in JAR Files

You've acquired a third-party JAR library that comes with two corresponding DLL files. Your Java application relies on this library, and you seek to merge all the components (your code, the third-party JAR, and DLLs) into a single, convenient JAR file.

Packaging the DLLs

JAR files essentially function like ZIP archives. To include DLLs in your JAR, simply place them anywhere within its structure. However, simply packaging the DLLs is not sufficient. Before using them, you must extract them from the JAR and save them to a designated location on your hard drive.

Code Examples

Here's an exemplary Java code block that demonstrates this process:

// Package the DLLs in the JAR file
// ... (your code here)

// Extract and load the DLLs from the JAR
private static void loadFromJar() {
    // Determine the temporary directory path
    String path = "AC_" + new Date().getTime();

    // Extract the DLLs and load them into memory
    loadLib(path, "acwrapper");
    loadLib(path, "aamapi51");
    loadLib(path, "libeay32");
}

// Extract and load a specific DLL
private static void loadLib(String path, String name) {
    InputStream in = Foo.class.getResourceAsStream("/lib-bin/" + name + ".dll");
    File fileOut = new File(System.getProperty("java.io.tmpdir") + "/" + path + "/lib-bin/" + name + ".dll");

    OutputStream out = FileUtils.openOutputStream(fileOut);
    IOUtils.copy(in, out);
    in.close();
    out.close();

    System.load(fileOut.toString());
}

In this code, the DLLs are extracted to the temporary directory specified by "path" and then loaded into memory using System.load(). Keep in mind, you may need to adjust the exact file paths and resource paths based on your specific JAR structure and DLL locations.

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