![]() Note: The following code works only on Windows platforms. The program below loads the Kernel32.dll and uses it to call the Beep and Sleep functions. Import import /** Simple example of native C POSIX library declaration and usage. Note: The following code is portable and works the same on Windows and POSIX ( Linux / Unix / macOS) platforms. The following program loads the local C standard library implementation and uses it to call the printf function. If the alignment details are not given in the documentation of the native library, the correct alignment must be determined by trial and error during implementation of the Java wrapper. JNA defaults to an OS platform specific setting, that can be overridden by a library specific custom alignment. Native libraries have no standardized memory byte alignment flavor. Memory byte alignment for data structures Note: The meaning of TCHAR changes between char and wchar_t according to some preprocessor definitions. Very often the Java code seeks to directly access functions inside of the WIN32 API. The following table shows an overview of types mapping between Java and native code and supported by the JNA library. Java Native Access (JNA) and Java Native Interface (JNI) are two frameworks that allow Java to directly call C-style functions located in executable libraries, such as Windows Dynamic Link Libraries (DLLs). It is also possible to tweak and recompile the native build configurations to make it work on most other platforms that run Java. JNA is built and tested on macOS, Microsoft Windows, FreeBSD / OpenBSD, Solaris, Linux, AIX, Windows Mobile, and Android. This makes it quite easy to take advantage of native platform features without incurring the high development overhead of configuring and building JNI code. The developer uses a Java interface to describe functions and structures in the target native library. The JNA library uses native functions allowing code to load a library by name and retrieve a pointer to a function within that library, and uses libffi library to invoke it, all without static bindings, header files, or any compile phase. The JNA library uses a small native library called foreign function interface library ( libffi) to dynamically invoke native code. 3 Memory byte alignment for data structures.
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