JNI的使用

最新推荐文章于 2025-08-12 21:03:53 发布

原创最新推荐文章于 2025-08-12 21:03:53 发布 · 448 阅读

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#jni #java

本文详细介绍了使用JNI(Java Native Interface)从Java调用本地C/C++代码的步骤：创建Java文件并调用C方法、从Java类文件生成头文件、使用GCC/G++编译器创建共享库、设置Java运行时库路径；并解释了本地程序如何接收参数、转换类型、执行操作及返回结果。

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JNI
1. create java file which call c method
2. generate *.h file from java class file
javap -cp . HelloJNI
3. create so file with gcc/g++ compiler
4. run java with -Djava.library.path=path_to_lib
The native programs:
3.1 Receive the arguments in JNI type (passed over by the Java program).
3.2 For reference JNI type, convert or copy the arguments to local native types, e.g., jstring to a C-string, jintArray to C’s int[], and so on. Primitive JNI types such as jint and jdouble do not need conversion and can be operated directly.
3.3 Perform its operations, in local native type.
3.4 Create the returned object in JNI type, and copy the result into the returned object.
3.5 Return.

jni example
https://www3.ntu.edu.sg/home/ehchua/programming/java/JavaNativeInterface.html
jni spec
http://docs.oracle.com/javase/7/docs/technotes/guides/jni/spec/jniTOC.html
jni tips
developer.android.com/training/articles/perf-jni.html