CPP calls JAVA function Demo through JNI

First, let's take a look at the two functions in our JAVA file. Both functions are very simple. Note that they are static.

package mm.nn.oo;  public class CJava {   public static String GetStr() {    return "THIS STRING IS FROM JAVA!!!";   }     public static int Add(int m, int n) {    return m + n;   }  }  

Then generate the corresponding. put the CLASS file in the directory mm \ nn \ n \ oo corresponding to the package name, and wait for it to be called by CPP. create a CPP project and add the JNI directory in "property =" configuration property = "VC ++": $ (JAVA_HOME) \ include \ win32 and $ (JAVA_HOME) \ include. add the library directory required to create a java vm in the library Directory: % JAVA_HOME % \ lib. then our CPP Code looks like this:

# Include
 
  
# Include
  
   
# Pragma comment (lib, "jvm") int main () {JavaVM * pJvm; // Virtual Machine pointer JNIEnv * pEnv; // environment pointer JavaVMInitArgs VM_Args; JavaVMOption Options [3]; VM_Args.version = JNI_VERSION_1_2; // this field must be set to this value Options [0]. optionString = "-Djava. compiler = NONE "; // disable loading Options by JIT compiler [1]. optionString = "-Djava. class. path =. ";//. CLASS File Path Options [2]. optionString = "-verbose: jni"; // The information used for tracking runtime VM_Args.version = JNI_VERSION_1_2; // the version number VM_Arg S. nOptions = 3; VM_Args.options = Options; VM_Args.ignoreUnrecognized = JNI_TRUE; if (JNI_CreateJavaVM (& pJvm, (void **) & pEnv, & VM_Args )! = JNI_ERR) {jclass JCls = pEnv-> FindClass ("mm/nn/oo/CJava"); system ("CLS "); printf ("************************************* * *********** \ n "); if (JCls! = 0) {jmethodID pMID = pEnv-> GetStaticMethodID (JCls, "Add", "(II) I"); if (pMID! = 0) {printf ("% I \ n", pEnv-> CallStaticIntMethod (JCls, pMID, 5, 5);} pMID = pEnv-> GetStaticMethodID (JCls, "GetStr ", "() Ljava/lang/String;"); if (pMID! = 0) {jstring TempStr = (jstring) pEnv-> CallStaticObjectMethod (JCls, pMID); const char * pTemp = pEnv-> GetStringUTFChars (TempStr, 0 ); printf ("% s \ n", pTemp); pEnv-> ReleaseStringUTFChars (TempStr, pTemp);} pEnv-> DeleteLocalRef (JCls);} pJvm-> DestroyJavaVM (); // release Virtual Machine}
  
 

Well, it's so simple. The final project download portal attached to this Demo: http://t.cn/8syetyV
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