Java jni calls c/c ++ dll

 

Create a Test folder and create a java class Test. java. The Code is as follows:

Public class Test {

Static {

System. loadLibrary ("Test ");

}

Public native int test ();

Public static void main (String [] args ){

Test test = new Test ();

System. out. println (test. test ());

}

}

Go to cmd and enter this directory. After java Test. java is compiled, javah-jni Test generates Test. h

This is a C header file with the following content:

/* Do not edit this file-it is machine generated */

# Include <jni. h>

/* Header for class Test */

 

# Ifndef _ Included_Test

# Define _ Included_Test

# Ifdef _ cplusplus

Extern "C "{

# Endif

/*

* Class: Test

* Method: test

* Signature: () I

*/

JNIEXPORT jint JNICALL Java_Test_test

(JNIEnv *, jobject );

 

# Ifdef _ cplusplus

}

# Endif

# Endif

The preceding include <jni. h> can be changed to include "jni. h". The jni. h file is in the include folder of the jdk directory and can be copied to the current Test directory.

Then create the C code file. The Test. c code is as follows:

# Include "test. h"

 

JNIEXPORT jint JNICALL Java_Test_test

(JNIEnv * env, jobject obj)

{

Return 1;

}

Then use the cl command (cl is the C compiler compilation command) to compile Test. c. The command is as follows:

Cl-Id: \ jdk \ include \ win32-LD Test. c (myDll. lib)-FeTest. dll

(MyDll. lib) is the code library used in your C code file. In this example, it is useless and does not need to be imported. The path specified by-Id indicates the header file required by jni. h file location. -LD indicates that the dynamic link library (dll) is to be generated.

Finally, let's Test the java Test running Test. class in the Test directory.