Load dll at runtime java

Load dll at runtime java

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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How to use .dll files in java code?

Here is my code : The problem is that I have this error on compilation : I already tried to : Set arguments in Eclipse Moving at root of project and System32 folder Added the folder path in native library location in Eclipse Example : java -Djava.library.path=»path/to/directory/containing/the/dll» -jar appli.jar in the code, load the dll explicitly, with System.load.

How to use .dll files in java code?

I have a .dll file, which i have to use in java. This .dll file has a parameterised method, which should return type as string. When i am passing parameter to it, i get the message as Native methods do not specify a body

package com.letme.test; public class Eagleye_parser < String n = "E48A7 F7759 65EA7"; public Eagleye_parser() <>static < System.loadLibrary("Eagleye_parser"); >public native String eagleye_fmu(n);// here it is giving msg : Native methods do not specify a body > 

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

Eclipse — Loading .DLL in Java, 3. +25. The first problem was it couldn’t find the dll because it wasn’t in the path. The second problem is that it can’t find the dependencies on the dll … Code samplepublic class DllTest Feedback

Loading .DLL in Java

I want to call a .DLL method in Eclipse. Here is my code :

class TestJNI1 < public native void LireNoVersion(); public void a() < System.loadLibrary("tttt.dll"); LireNoVersion(); >> public GlobalAction()

The problem is that I have this error on compilation :

Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: Expecting an absolute path of the library: tttt.dll at java.lang.Runtime.load0(Unknown Source) at java.lang.System.load(Unknown Source) 

• Set arguments in Eclipse
• Moving at root of project and System32 folder
• Added the folder path in native library location in Eclipse
• Changing the %PATH% in windows
• Giving the absolute path as an argument
• Trying with «tttt.dll», «./tttt.dll» and «.tttt.dll»
• Call with System.loadLibrary(. ) and System.load(. )

I tried to print the java.library.path and get a path. I put the dll in this path and the error message is more confusing now :

Exception in thread "AWT-EventQueue-0" java.lang.UnsatisfiedLinkError: D:\My\Exact\Path\tttt.dll: Can't find dependent libraries 

Here is the code to print the path :

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

The first problem was it couldn’t find the dll because it wasn’t in the path.

The second problem is that it can’t find the dependencies on the dll that you are using. Your choices would seem to be

Give the absolute path of the file

 try < System.load("C:/myapplication/application.dll"); >catch (UnsatisfiedLinkError e) < System.err.println("Native code library failed to load.\n" + e); System.exit(1); >> 

Using the Library interface in the sun.jna package did the trick :

 import com.sun.jna.Library; import com.sun.jna.Native; public class DllTest < public interface IDLL extends Library < IDLL INSTANCE = (simpleDLL) Native.loadLibrary("tttt", IDLL.class); int LireNoVersion(); // DWORD LireNoVersion(); >public static void main(String[] args) < IDLL sdll = IDLL.INSTANCE; int nover = sdll.LireNoVersion(); System.out.println("version = " + nover + "\n"); >> 

Still don’t know why it didn’t worked before.

Check if a dll library is already loaded? (Java), static < System.loadLibrary ("LibFile"); >within the class declaration. When the class is loaded and initialized, the necessary native code …

How to configure .dll file in Java?

This jacob jar file comes with a .dll file. I have added Jacob jar file to my classpath. But when I execute my application a runtime error occurs as

"couldn't load jacob-1.15-M3-x86.dll file" 

How can I load this .dll file?

I had set the «path» environment varaible to the dir that contains my .dll file and loading that .dll file as follows

but the following error occured

 java.lang.UnsatisfiedLinkError: no jacob-1.15-M3-x86.dll in java.library.path at java.lang.ClassLoader.loadLibrary(ClassLoader.java:1734) at java.lang.Runtime.loadLibrary0(Runtime.java:823) at java.lang.System.loadLibrary(System.java:1028) at TemplateClass.TemplateClass.(TemplateClass.java:14) 

The ‘jacob-1.15-M3-x86.dll’ needs to be in a place where your the operating system can find it. You have a few options here:

• You can place the .dll file in the directory you started your application from. If you have a batch script to start your application, it would be that directory. If you are starting in some sort of application server, it would typically be the ‘bin’ directory.
• You can place the .dll file somewhere in the %PATH% environment variable. I may be easier to just update your PATH environment variable to include the directory that contains your .dll file.
• Another option is to place your .dll into the %SystemRoot%\system32 directory. Usually this is ‘C:\Windows\system32’. This option is not usually recommended unless it is a shared library like the MSCVRT runtime.

One other possible issue you might have. If the .dll is compiled as 32-bit, then you must be running in the 32-bit Java runtime. Likewise, if it is a 64-bit .dll it needs to be run in a 64-bit JRE.

Ah, that’s not a compilation error but a runtime error.

My guess would be that your DLL needs to be on the PATH . Not CLASSPATH , but PATH , because that’s where Windows looks for DLLs. Try either extending your PATH to include the location of your DLL, or do what many other people do: Dump the DLL into \Winnt\System\System32 or whatever the system directory is called on your box. Wherever all the other DLLs are, in other words.

The error message you post, thankfully, is pointing out the exact problem. You can solve it by putting the directory containing your DLL into java.library.path This Sun forum thread shows a nice example: http://forums.sun.com/thread.jspa?threadID=627890

Actually, that’s a lot less clean than it should be; this seems to be one of the «shadier» areas in Java. The thread wanders around a lot, I do advise you to read all the way through to see some problems and solutions. I think you’ll be able to succeed with a little trial and error.

• set the property java.library.path to the directory containing the dll. Example : java -Djava.library.path=»path/to/directory/containing/the/dll» -jar appli.jar
• in the code, load the dll explicitly, with System.load.

You need to set LD_LIBRARY_PATH. This will give you all the right steps to follow.

Accessing dll methods in java, I am trying to accessing dll methods in java which has been written in c#. From the following code i am trying to build dll which is generated …

How to call dll files in java

I need to call a DLL file advapi32.dll in java so that i can use its CryptEncrypt function for Encryption. Is it possible to access the functions of the dll files through JNI or is there any other better ways

advapi32.dll is found in system32 folder of windows

System.loadLibrary("advapi32"); 

Runtime.getRuntime().loadLibrary("C:/Windows/System32/crypt32.dll"); 

Runtime.getRuntime().loadLibrary() giving the following errors

Exception in thread "main" java.lang.UnsatisfiedLinkError: no C:/Windows/System32/crypt32.dll in java.library.path at java.lang.ClassLoader.loadLibrary(Unknown Source) at java.lang.Runtime.loadLibrary0(Unknown Source) at java.lang.Runtime.loadLibrary(Unknown Source) at mail.encrypt.main(encrypt.java:17) 

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 — Where to put DLL file?, One such way to do so is to put the path to the DLL in PATH environment variable. Other option is to add it to the VM arguments in the …

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