Java loading dll from jar

Java java load dll from resource code example

If your are using Eclispe then right click on your project->Then click on Build path-> then click on Add libraries after that click on user library Here you can import the dll Solution 3: The ‘n’ here is the problem as it would be a problem with any other java function declaration. Any further linker errors could be from dependency problems with finding other DLLs.

Loading DLL in Java

Where you specify the DLL filename in the library path, omit that. Additionally, your System.loadLibrary call should just be ‘mydll’. I can tell you (from experience) that if you put the DLL in the root of your project in Eclipse (i.e., D:\Eclipse Workspace\Proj), it should work. Any further linker errors could be from dependency problems with finding other DLLs. The exception is the same. Use something like Dependency Walker (http://www.dependencywalker.com/) to see if your DLL relies on anything else not on the system library path.

Edit: UnsatisfiedLinkError : Thrown if the Java Virtual Machine cannot find an appropriate native-language definition of a method declared native — it seems like you are using a JNI function which does not exist.

One problem you have is: System.load(«D:\mydll.dll»); should be System.load(«D:\\mydll.dll»); or System.load(«D:/mydll.dll»);

I have had more success with System.load, but loadlibrary is better designed for multiplatform. It figures out the extension for you.

Check out how to properly set up the native dependencies here. Additionally, make sure you use the correct JVM: in my case, the DLL was not found because it was a 32 bit DLL, but I used the x64 JVM!

Net — how to use .dll files in java code?, 0. Simple add the reference in you project. and the namespace at the top.. then you can access the all dll methods. If your are using Eclispe then right click on your project->Then click on Build path-> then click on Add libraries after that click on user library. Here you can import the dll. Share.

How to use .dll files in java code?

Try having a look at JNA, it provides a nice wrapper layer around native code.

Simple add the reference in you project. and the namespace at the top.. then you can access the all dll methods. If your are using Eclispe then right click on your project->Then click on Build path-> then click on Add libraries after that click on user library

Here you can import the dll

public native String eagleye_fmu(n); The ‘n’ here is the problem as it would be a problem with any other java function declaration.

This should be something like public native String eagleye_fmu(String); then you call the native function like any other function String result = eagleye_fmu(n);

This is all assuming you have the dll implemented properly

Java — Load .DLL with applet and use it on client, 1 Answer. Certainly. The applet will need to be digitally signed by the developer, and trusted by the end user (they click ‘OK’ when prompted). Put the natives in the root of a Jar and add it to the run-time class-path of the applet, using a reference in the archive attribute. Using the traditional method of deploying …

How to call dll files in java

Specify the lib path using below command

java -Djava.library.path=C:/Windows/System32/ 

Or use below hacking way inside code

System.setProperty( "java.library.path", "C:/Windows/System32/" ); Field fieldSysPath = ClassLoader.class.getDeclaredField("sys_paths"); fieldSysPath.setAccessible( true ); fieldSysPath.set( null, null ); 

Java — How to reference a .dll from a .jar file, It can depend on how the library is loaded in the java source code. Do you have access to this? Can you post the code? If the java code uses System.load(String) it will expect the full path to the dll. If it uses System.loadLibrary(String) it expects only the library name and will seach in the …

Loading dll using loadLibrary

Apparently, the loadLibrary() Documentation has managed to fool me a bit. In case of an UnsatisfiedLinkError it states

UnsatisfiedLinkError — if the library does not exist.

Therefore, I obviously assumed that loadLibrary() at no point was capable of seeing my specified library. That is, however, not the case as this exception can also mean that it found the according library in a wrong (incompatible with the VM) bitness.

As far as I understand it, the only check you can do to find out which UnsatisfiedLinkError you have exactly, is to break down the error message contained by the exception. What I ended up doing is along the lines of:

try < System.setProperty(JAVA_LIBPATH_PROPNAME, libpath); ForceReloadLibraryPath(); System.loadLibrary("AdsToJava"); >catch (UnsatisfiedLinkError ex) < // We simply did not find the dll if (ex.getMessage().equals("no MyLibrary in java.library.path")) < // Just alert that nothing was found >else if ( (ex.getMessage().endsWith("Can't load IA 32-bit .dll on a AMD 64-bit platform")) || (ex.getMessage().endsWith("Can't load AMD 64-bit .dll on a IA 32-bit platform")) ) < // Extract the path at which the dll whith the wrong bitness was found // and remove it from the search path and try again >> 

You could obviously also pre-check the search path prior to calling loadLibrary but as this method also works in cases where users copy the dlls allover the search path I thought this to be the most powerful option.

How to call external dll function from java code, You will need to use the Java Native Interface (JNI), which is a set of C/C++ functions that allow native code to interface with java code (i.e. receiving parameters from java function calls, returning results, etc). Write a wrapper C library that receive JNI calls and then call your external library. For instance, the …

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loading dll from a jar

We have seen that from WebStart we can load libraries which are in the package.
How does WebStart achieve this?

How can I load the .dll from the jar?
(I know that I can unpack all the jar file in a temporal directory and then load the library from there, but this is not a solution)

For start your DLL should be available in the PATH not in the CLASSPATH.

Experts Exchange is like having an extremely knowledgeable team sitting and waiting for your call. Couldn’t do my job half as well as I do without it!

Perhaps your dll is referencing other libraries which need to be loaded first.

Try to know which dlls your dll is referencing first, and load them before making System.loadLibrary(«test») ;

stranxe the DLL hasn’t got anything to do with the CLASSPATH as it is not a class. You need to put it somewhere where the PATH points at.

Also take a look at the link I posted, it gives some clues.

Thank you for all your comments.
I have also seen the link girionis sent me.

The dll I am trying to load is extremely simple, I have done it myself, it doesn’t need any other dll and it just prints «hello world».
If I put the dll in the current directory, instead of inside the .jar, it works fine.

This question is very simple and have been asked a lot of times before, in the news. However, the answer seems more difficult.
Some people just say that it is not possible to load a dll from a jar. I don’t want to hear this answer, unless you can show me that it is written somewhere by the java developers.

So again, any idea how to load a dll from a jar?

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Java loading dll from jar

There are several ways to make it possible for the Java runtime to find and load a dynamic library (DLL) at runtime. I will list them briefly here, followed by examples and further explanation below.

1. Call System.load to load the DLL from an explicitly specified absolute path.
2. Copy the DLL to one of the paths already listed in java.library.path
3. Modify the PATH environment variable to include the directory where the DLL is located.
4. Specify the java.library.path on the command line by using the -D option.
5. If using Eclipse, set the java.library.path in Eclipse for development/debugging.

Note: To help resolve an UnsatisfiedLinkError Runtime Error, see How to Handle the UnsatisfiedLinkError Runtime Error in Java

1. Call System.load to load the DLL from an explicitly specified absolute path.

This choice removes all uncertainty, but embeds a hard-coded path within your Java application. Example:

import com.chilkatsoft.CkZip; public class Test < static < try < System.load("C:/chilkatJava/chilkat.dll"); > catch (UnsatisfiedLinkError e) < System.err.println("Native code library failed to load.\n" + e); System.exit(1); >> public static void main(String argv[]) < CkZip zip = new CkZip(); System.out.println(zip.version()); >>

2. Copy the DLL to one of the paths already listed in java.library.path

To see the current value of the PATH environment variable, open a MS-DOS prompt and type:

Another way of viewing the java.library.path is to run this Java code:

String property = System.getProperty(«java.library.path»); StringTokenizer parser = new StringTokenizer(property, «;»); while (parser.hasMoreTokens())

Note: The java.library.path is initialized from the PATH environment variable. The directories may be listed in a different order, and the current directory «.» should be present in java.library.path, but may not be listed in the PATH environment variable.

The loadLibrary method may be used when the directory containing the DLL is in java.library.path. To load «chilkat.dll», call System.loadLibrary(«chilkat»), as shown here:

import com.chilkatsoft.CkZip; public class Test < static < try < System.loadLibrary("chilkat"); > catch (UnsatisfiedLinkError e) < System.err.println("Native code library failed to load.\n" + e); System.exit(1); >> public static void main(String argv[]) < CkZip zip = new CkZip(); System.out.println(zip.version()); >>

3. Modify the PATH environment variable to include the directory where the DLL is located.

Do this by modifying the PATH environment variable from the Windows Control Panel.

1. Start -> Control Panel -> System -> Advanced
2. Click on Environment Variables, under System Variables, find PATH, and click on it.
3. In the Edit windows, modify PATH by adding the location of the class to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the location of the class as the value.
4. Close the window.
5. Reopen Command prompt window, and run your java code.

1. Right click «My Computer» icon
2. Choose «Properties» from context menu
3. Click «Advanced» tab («Advanced system settings» link in Vista)
4. In the Edit windows, modify PATH by adding the location of the class to the value for PATH. If you do not have the item PATH, you may select to add a new variable and add PATH as the name and the location of the class as the value.
5. Reopen Command prompt window, and run your java code.

Important: Setting the PATH environment variable from a MS-DOS command prompt has no effect on java.library.path. For example, this does not work:

set PATH=c:\chilkatJava;%PATH% java Test

Also, modifying the java.library.path from within Java code does not work either:

static < try < // Adding a directory to java.library.path here will not change anything. // System.loadLibrary will still look in the directories listed in java.library.path // as it existed at the very start of the program. // The extra directory path added to java.library.path will not // be searched by loadLibrary. String libpath = System.getProperty("java.library.path"); libpath = libpath + ";C:/chilkatJava"; System.setProperty("java.library.path",libpath); System.loadLibrary("chilkat"); >catch (UnsatisfiedLinkError e) < System.err.println("Native code library failed to load.\n" + e); System.exit(1); >>

4. Specify the java.library.path on the command line by using the -D option.

java -Djava.library.path=c:\chilkatJava TestApp

5. If using Eclipse, set the java.library.path in Eclipse for development/debugging.

1. Open Project->Properties, select «Java Build Path», click on the «Add External JARs. » button and add the «chilkat.jar»
2. (still within the Project Properties dialog) Click on the «Run/Debug Settings», select your Java class, then click on the «Edit. » button. Select the «Arguments» tab, then add -Djava.library.path=»C:\chilkatJava;$» where «C:\chilkatJava» is the directory path containing the «chilkat.dll» file.

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