The process is almost the same, with just a few changes.
#Java native access code#
The number of elements in the array is also known (variable “numberOfResults”, see above). Not only can native code interface with Java, it can also draw on a Java Canvas, which is possible with the Java AWT Native Interface. 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: Similarly, J/Direct was easier to use than using the necessary intermediate native library and JNI, although at present JNA is an alternative. 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”. Java Native Access (JNA) is a community-developed library that provides Java programs easy access to native shared libraries without using the Java Native Interface. 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).
It could have been created with Microsoft Visual Studio C++.
This blog post is about the interoperation of Java with a native DLL.
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