How to Make a Jar File That Includes Dll Files

How to make a JAR file that includes DLL files?

Just package it anywhere in the jar. One thing you have to keep in mind though - before you can use the DLLs you need to actually extract these from the JAR and dump these on the hard disk somewhere otherwise you won't be able to load these

So basically - I did JNI project for the client where I will use such jar packaged within the war. However - before running any native methods I would get the DLL as a resource and write it to the disc into temp directory. Then I would run regular initialization code where my DLL is set to the same location I just wrote DLL to

Oh, and just in case: there's nothing special about packaging dll or any other file into jar. It's just like packaging stuff into zip

Here's some code I just digged out

public class Foo {
private static final String LIB_BIN = "/lib-bin/";
private final static Log logger = LogFactory.getLog(ACWrapper.class);
private final static String ACWRAPPER = "acwrapper";
private final static String AAMAPI = "aamapi51";
private final static String LIBEAU = "libeay32";

static {
    logger.info("Loading DLL");
    try {
        System.loadLibrary(ACWRAPPER);
        logger.info("DLL is loaded from memory");
    } catch (UnsatisfiedLinkError e) {
        loadFromJar();
    }
}

/**
 * When packaged into JAR extracts DLLs, places these into
 */
private static void loadFromJar() {
    // we need to put both DLLs to temp dir
    String path = "AC_" + new Date().getTime();
    loadLib(path, ACWRAPPER);
    loadLib(path, AAMAPI);
    loadLib(path, LIBEAU);
}

/**
 * Puts library to temp dir and loads to memory
 */
private static void loadLib(String path, String name) {
    name = name + ".dll";
    try {
        // have to use a stream
        InputStream in = ACWrapper.class.getResourceAsStream(LIB_BIN + name);
        // always write to different location
        File fileOut = new File(System.getProperty("java.io.tmpdir") + "/" + path + LIB_BIN + name);
        logger.info("Writing dll to: " + fileOut.getAbsolutePath());
        OutputStream out = FileUtils.openOutputStream(fileOut);
        IOUtils.copy(in, out);
        in.close();
        out.close();
        System.load(fileOut.toString());
    } catch (Exception e) {
        throw new ACCoreException("Failed to load required DLL", e);
    }
}
    // blah-blah - more stuff
}

Where to put my .dll to be accessed in my jar

Just package it anywhere in the jar. One thing you have to keep in mind though - before you can use the DLLs you need to actually extract these from the JAR and dump these on the hard disk somewhere otherwise you won't be able to load these

How to make a JAR file that includes DLL files?

How to make a executable jar file with .dll - RXTX

You have a few options. Try to copy the .dll files in the runtime folder and override the files at each start of your program. A second option is to copy the files in a fix folder and add the path of the folder to the environment variables in MS Windows. You can also override the files at each start.

Another possibility is to add the temporary folder to the MS Windows environment variables at runntime. But be careful with this solution, for more information read this post.

static {
    try {
        System.loadLibrary(RXTXSERIAL);
        System.loadLibrary(RXTXPARALLEL);
    } catch (UnsatisfiedLinkError exc) {
        initLibStructure();
    }
}

private static void initLibStructure() {

    try {
        //runntime Path
        String runPath = new File(".").getCanonicalPath();

        //create folder
        File dir = new File(runPath + "/" + LIB);
        dir.mkdir();

        //get environment variables and add the path of the 'lib' folder
        String currentLibPath = System.getProperty("java.library.path");
        System.setProperty("java.library.path",
                currentLibPath + ";" + dir.getAbsolutePath());

        Field fieldSysPath = ClassLoader.class
                .getDeclaredField("sys_paths");
        fieldSysPath.setAccessible(true);
        fieldSysPath.set(null, null);

        loadLib(runPath, RXTXPARALLEL);
        loadLib(runPath, RXTXSERIAL);

    } catch (Exception e) {
        e.printStackTrace();
    }
}

private static void loadLib(String path, String name) {
    name = name + ".dll";
    try {
        InputStream in = ResourceLoader.load(LIB + name);
        File fileOut = new File(path + "/" + LIB + name);

        OutputStream out = FileUtils.openOutputStream(fileOut);
        IOUtils.copy(in, out);
        in.close();
        out.close();
        System.load(fileOut.getAbsolutePath());
    } catch (Exception e) {
        e.printStackTrace();
    }
}

ANT Java-Jar task to include native DLL

You can't use DLL files when they're still packaged in the jar.

I suggest you create an application folder where your .jar will be located at and next to the .jar, put your DLL files there. In your application you will need to load your DLLs from that location.

Executable Jar with Dependency on dll

I would presume this has something to do with putting the dll's in your library

(In Eclipse, Properties->Java Build Path->Libraries).

When you export the jar, you also will have the option of exporting the library files into a folder.

If you decompile the Jar after that, you'll notice that there's a manifest file, and in it, paths to where your library files are (based on the export, which created a library folder for you, generally jarname_lib).

When you export, you have the option to save as ANT file, which you can then edit to change the export location of the library files to a folder name of your choice. You can then add this edited ANT file to your build so that it happens whenever you build the project:

(In Eclipse, Properties->Builders->New)

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