PRB: Getting "Unsatisfied Link Error" When Using J/Direct

SYMPTOMS

The following error message is generated when trying to run a Java
application or applet that uses J/Direct:

Error: Java.lang.unsatisified link error...

CAUSE

This error can occur if an old version of the Java Language Compiler (JVC)
is used. Make sure you are using Jvc.exe version 4337 or later. Version
4337 is shipped with the Microsoft SDK 2.0 for Java. Since J/Direct
requires the use of compile-time directives like @dll.import (to import
native methods from a DLL) it requires the latest version of Jvc.exe, which
can recognize these compile-time directives.


NOTE: Microsoft virtual machine build 2252 (or higher) is required for
J/Direct.

RESOLUTION

After you have installed the SDK for Java 2.0 or later, if you are trying
to build your Java applet or application that uses J/Direct from within the
Developer Studio, then add the SDK-Java\Bin directory to the Visual J++
executable files path as follows:

  1. From the Tools menu, point to Options and click the Directories tab.
  2. Under the Platform menu, make sure "Java Virtual Machine" is selected.
  3. Under "Show directories for," choose "Executable files."
  4. Include the directory "C:\SDK-Java\Bin" and click the up arrow until it
    is the first directory listed in the list box.
Or you can use the following steps instead:

  1. Back up your current Visual J++'s copy of Jvc.exe. You can locate this
    file in C:\Program Files\DevStudio\SharedIDE\bin.
  2. Then copy the following files from your SDK-Java\Bin directory
    (C:\SDK-Java\Bin) to C:\Program Files\DevStudio\SharedIDE\bin:


    • Jvc.exe
    • Jps.dll
    • Msjvc.dll.

STATUS

This behavior is by design.

MORE INFORMATION

The following is a check-list that you can use to trouble-shoot this
problem if you are still seeing this error after upgrading to the Jvc.exe
version 4337 or later.

  1. Make sure your DLL is visible on the system path. DLLs are searched for
    in the following locations (in order):

    1. The directory from which the application (typically jview) is loaded
    2. The current directory
    3. The Windows system directory
    4. The Windows directory
    5. The directories listed in the PATH environment variable
  2. The Microsoft virtual machine will not attempt to load the DLL until a
    method requiring it is actually called. Therefore, do not assume that
    the DLL load was successful simply because the Java class loaded
    successfully. Check the method qualifiers. Methods declared with the
    @dll.import directive must be native and static. They can have any level
    of access (public, private, and so on) supported by the Java language.
  3. Make sure that your method name matches the DLL export name exactly,
    including capitalization. The DLL linking mechanism in Win32 is
    case-sensitive.
  4. If you still have trouble linking to a method, use a utility such as
    dumpbin /exports (shipped with Visual C++) to verify that the DLL
    exports the method by the name you are using. Some DLLs may require you
    to link to exports by ordinal (an integer) rather than a name. In such a
    case, use the entrypoint override on the method using the "#ordinal"
    syntax as in the following example:

          // This method is exported as ordinal #34.      /** @dll.import("MyDll",entrypoint="#34") */       public static native void MySample();
  5. Be aware that some so-called functions are actually C macros and the
    actual DLL export name may be quite different from the name of the
    macro.
  6. Having a single @dll.import directive within a class definition, before
    all the method declarations inside that class, may also result in an
    UnsatisfiedLinkError. So try specifying the @dll.import prior to the
    class definition to set a library name for all native methods declared
    in that class. For example:

          /** @dll.import("KERNEL32") */       class Test     {         public static native int GetEnvironmentStrings();         public static native int GetEnvironmentVariable(String name,                                                     StringBuffer value,                                                     int ccbValue);      }
This is equivalent to specifying @dll.import for each method. Also using
the @dll.import directive at the class level saves space in the .class file
and eliminates redundant information.

REFERENCES

For more information about J/Direct, visit the following page on the
Microsoft Web site:

For more information on Updating the Visual J++ 1.x compiler, please see
the SDK for Java documentation and the following article in the Microsoft
Knowledge Base:

177165 INFO: Use New Java 1.1 Language Features with Visual J++ 1.1
For the latest Knowledge Base articles and other support information on
Visual J++ and the SDK for Java, see the following pages on the Microsoft
Technical Support site:

Propiedades

Id. de artículo: 180713 - Última revisión: 02/14/2017 - Revisión: 1

Microsoft Software Development Kit for Java 2.02, Microsoft Software Development Kit for Java 2.02, Microsoft Software Development Kit for Java 3.1, Microsoft Software Development Kit for Java 2.01, Microsoft Software Development Kit for Java 2.02, Microsoft Software Development Kit for Java 2.02, Microsoft Software Development Kit for Java 3.0, Microsoft Virtual Machine for Java, Microsoft Visual J++ 1.0 Standard Edition, Microsoft Visual J++ 1.1 Standard Edition

Comentarios