The number of elements in the array is also known (variable “numberOfResults”, see above). With the knowledge about the C-struct (sequence and data type of member variables), the java program can read and convert the memory content to create adequate objects. We map the return type of the function as a in Java. You can find a discussion of this issue here: in a C++ forumĬreate Java objects from an array of C-structs The Java program cannot free the memory itself, because the DLL uses a separate heap manager. Public interface ExampleDLL extends Library #define EXAMPLE_DLL extern "C" _declspec(dllexport)ĮXAMPLE_DLL char* returnDLLVersion() Java: Here are some technical details of interesting integration problems, depending on the signature of the DLL functions, that need to be invoked:ĭepending on the calling convention that the DLL expects, the wrapper interface needs to inherit from “” or “32.StdCallLibrary”. You basically create a Java interface to wrap the DLL functions to be invoked, but… If you use maven to build the project, just add the dependency: The JNA framework consists of a single jna.jar and can be downloaded here: Java Native Access (JNA) – downloads and documentation. The usual low-level way is to use JNI to access the DLL, but this is much more error-prone and less productive than using JNA. The DLL links the static link library and is a “Multi-threaded DLL” with “No Common Language Runtime support”.įrom the Java side, you have the choice between Java Native Interface (JNI) and Java Native Access (JNA). Java Native Access (JNA) The definitive JNA reference (including an overview and usage details) is in the JavaDoc.Please read the overview.Questions, comments, or exploratory conversations should begin on the mailing list, although you may find it easier to find answers to already-solved problems on StackOverflow. It could have been created with Microsoft Visual Studio C++. The project is in Java and I am trying to avoid directly including C code, so I have been using Java Native Access, which masks things like winapi. This blog post is about the interoperation of Java with a native DLL.
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