java lang UnsatisfiedLinkError no dll in java library path

Question

How can I load a custom dll file in my web application  I ve tried the following   Copied all required dlls in system32 folder and tried to load one of them in Servlet constructor System loadLibrary Copied required dlls into tomcat home shared lib and tomcat home common lib  All these dlls are in WEB-INF lib of the web-application

User · Answer

In the case where the problem is that System.loadLibrary cannot find the DLL in question, one common misconception (reinforced by Java's error message) is that the system property java.library.path is the answer. If you set the system property java.library.path to the directory where your DLL is located, then System.loadLibrary will indeed find your DLL. However, if your DLL in turn depends on other DLLs, as is often the case, then java.library.path cannot help, because the loading of the dependent DLLs is managed entirely by the operating system, which knows nothing of java.library.path. Thus, it is almost always better to bypass java.library.path and simply add your DLL's directory to LD_LIBRARY_PATH (Linux), DYLD_LIBRARY_PATH (MacOS), or Path (Windows) prior to starting the JVM.

(Note: I am using the term "DLL" in the generic sense of DLL or shared library.)

User · Answer

The original answer by Adam Batkin will lead you to a solution  but if you redeploy your webapp  without restarting your web container   you should run into the following error   java lang UnsatisfiedLinkError  Native Library  foo  already loaded in another classloader    at java lang ClassLoader loadLibrary0 ClassLoader java 1715     at java lang ClassLoader loadLibrary ClassLoader java 1646     at java lang Runtime load0 Runtime java 787     at java lang System load System java 1022    This happens because the ClassLoader that originally loaded your DLL still references this DLL   However  your webapp is now running with a new ClassLoader  and because the same JVM is running and a JVM won t allow 2 references to the same DLL  you can t reload it   Thus  your webapp can t access the existing DLL and can t load a new one   So     you re stuck     Tomcat s ClassLoader documentation outlines why your reloaded webapp runs in a new isolated ClassLoader and how you can work around this limitation  at a very high level    The solution is to extend Adam Batkin s solution a little      package awesome      public class Foo            static               System loadLibrary  foo                          required to work with JDK 6 and JDK 7         public static void main String   args                       Then placing a jar containing JUST this compiled class into the TOMCAT HOME lib folder   Now  within your webapp  you just have to force Tomcat to reference this class  which can be done as simply as this     Class forName  awesome Foo      Now your DLL should be loaded in the common classloader  and can be referenced from your webapp even after being redeployed   Make sense   A working reference copy can be found on google code  static-dll-bootstrapper

User · Answer

For those who are looking for java lang UnsatisfiedLinkError  no pdf java in java library path  I was facing same exception  I tried everything and important things to make it work are    Correct version of pdf lib jar   In my case it was wrong version jar kept in server runtime   Make a folder and keep the pdflib jar in it and add the folder in your PATH variable   It worked with tomcat 6

User · Answer

First  you ll want to ensure the directory to your native library is on the java library path  See how to do that here  Then  you can call System loadLibrary nativeLibraryNameWithoutExtension  - making sure to not include the file extension in the name of your library

User · Answer

I had the same problem and the error was due to a rename of the dll  It could happen that the library name is also written somewhere inside the dll  When I put back its original name I was able to load using System loadLibrary

User · Answer

Poor me   spent a whole day behind this Writing it down here if any body replicates this issue   I was trying to load as Adam suggested but then got caught with AMD64 vs IA 32 exception If in any case after working as per Adam s no doubt the best pick  walkthrough try to have a 64 bit version of latest jre Make sure your JRE AND JDK are 64 bit and you have correctly added it to your classpath   My working example goes here unstatisfied link error

User · Answer

It is simple just write java -XshowSettings properties on your command line in windows and then paste all the files in the path shown by the java library path

User · Answer

I m using Mac OS X Yosemite and Netbeans 8 02  I got the same error and the simple solution I have found is like above  this is useful when you need to include native library in the project  So do the next for Netbeans   1 - Right click on the Project 2 - Properties 3 - Click on RUN 4 - VM Options  java -Djava library path  your path  5 - for example in my case  java -Djava library path  lt  Users Lexynux NetBeansProjects NAO libs gt  6 - Ok   I hope it could be useful for someone  The link where I found the solution is here  java library path     What is it and how to use

User · Answer

In order for System loadLibrary   to work  the library  on Windows  a DLL  must be in a directory somewhere on your PATH or on a path listed in the java library path system property  so you can launch Java like java -Djava library path  path to dir    Additionally  for loadLibrary    you specify the base name of the library  without the  dll at the end  So  for  path to something dll  you would just use System loadLibrary  something     You also need to look at the exact UnsatisfiedLinkError that you are getting  If it says something like   Exception in thread  main  java lang UnsatisfiedLinkError  no foo in java library path   then it can t find the foo library  foo dll  in your PATH or java library path  If it says something like   Exception in thread  main  java lang UnsatisfiedLinkError  com example program ClassName foo  V   then something is wrong with the library itself in the sense that Java is not able to map a native Java function in your application to its actual native counterpart   To start with  I would put some logging around your System loadLibrary   call to see if that executes properly  If it throws an exception or is not in a code path that is actually executed  then you will always get the latter type of UnsatisfiedLinkError explained above   As a sidenote  most people put their loadLibrary   calls into a static initializer block in the class with the native methods  to ensure that it is always executed exactly once   class Foo        static           System loadLibrary  foo               public Foo

User · Answer

For windows I found that when i loaded the filles jd2xsx dll calls  amp  ftd2xx dll  into the windowws system32 folder this resolved the issues   I then had an issue with my newer fd2xx dll having to do with parameters which is why I had to load the older version of this dll   I will have to ferrit this out later   Note   the jd2xsx dll calls the ftd2xx dll so just setting the path for the jd2xx dll might not work

User · Answer

You can use System load   to provide an absolute path which is what you want  rather than a file in the standard library folder for the respective OS   If you want native applications that already exist  use System loadLibrary String filename   If you want to provide your own you re probably better with load     You should also be able to use loadLibrary with the java library path set correctly  See ClassLoader java for implementation source showing both paths being checked  OpenJDK

User · Answer

If you believe that you added a path of native lib to  PATH   try testing with   System out println System getProperty  java library path       It should show you actually if your dll is on  PATH    Restart the IDE Idea  which appeared to work for me after I setup the env variable by adding it to the  PATH

User · Answer

If you need to load a file that s relative to some directory where you already are  like in the current directory   here s an easy solution   File f   if  System getProperty  sun arch data model   equals  32             32-bit JVM     f   new File  mylibfile32 so      else          64-bit JVM     f   new File  mylibfile64 so      System load f getAbsolutePath

User · Answer

Changing  java library path  variable at runtime is not enough because it is read only once by JVM  You have to reset it like   System setProperty  java library path   path     set sys paths to null final Field sysPathsField   ClassLoader class getDeclaredField  sys paths    sysPathsField setAccessible true   sysPathsField set null  null     Please  take a loot at  Changing Java Library Path at Runtime

[java] java.lang.UnsatisfiedLinkError no *****.dll in java.library.path

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