Java example source code file (jinvoker.cpp)

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Java - Java tags/keywords

callstaticvoidmethod, classpath, destroyjavavm, findclass, freejavavminitargs, getstaticmethodid, javavminitargs, javavminitargs\*, javavmoption, jni_true, jnienv, makejavavminitargs, newobjectarray, null

The jinvoker.cpp Java example source code

/*
 * Copyright (c) 2006, 2011, Oracle and/or its affiliates. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 *   - Redistributions of source code must retain the above copyright
 *     notice, this list of conditions and the following disclaimer.
 *
 *   - Redistributions in binary form must reproduce the above copyright
 *     notice, this list of conditions and the following disclaimer in the
 *     documentation and/or other materials provided with the distribution.
 *
 *   - Neither the name of Oracle nor the names of its
 *     contributors may be used to endorse or promote products derived
 *     from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS
 * IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO,
 * THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE COPYRIGHT OWNER OR
 * CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
 * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF
 * LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 */

/*
 * This source code is provided to illustrate the usage of a given feature
 * or technique and has been deliberately simplified. Additional steps
 * required for a production-quality application, such as security checks,
 * input validation and proper error handling, might not be present in
 * this sample code.
 */


#include <memory.h>
#include <stdlib.h>
#include "jinvokerExp.h"

static int g_nExitCode = 0;

void system_exit(jint nCode){
    g_nExitCode = nCode;
}

/*
Allocating and providing the JVM init argumets.
By MakeJavaVMInitArgs() it is provided two options: providing CLASSPATH
environment variable value and function java.lang.System.exit()
redefinition in order to get the exit code.
See the description of the JNI API in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/invocation.html#wp9502
*/

int MakeJavaVMInitArgs( void** ppArgs ){

    int nOptSize = 2;
    JavaVMInitArgs* pArgs    = new JavaVMInitArgs();
    JavaVMOption*   pOptions = new JavaVMOption[nOptSize];

    //provide CLASSPATH value to java.class.path

    char* szClassPath = getenv("CLASSPATH");
    if( szClassPath == NULL )
        szClassPath = ".";

    pOptions[0].optionString = new char[strlen("-Djava.class.path=")+
                                        strlen(szClassPath)+1];
    sprintf( pOptions[0].optionString, "-Djava.class.path=%s", szClassPath );

    //redefine java.lang.System.exit()

    pOptions[1].optionString = "exit";
    pOptions[1].extraInfo    = system_exit;

    //Fill the arguments

    memset(pArgs, 0, sizeof(JavaVMInitArgs));
    pArgs->version = 0x00010002;
    pArgs->options = pOptions;
    pArgs->nOptions = nOptSize;
    pArgs->ignoreUnrecognized = JNI_TRUE;

    *ppArgs = pArgs;

    return 0;
}

/*
Free the allocated JVM init argumets
*/

void FreeJavaVMInitArgs( void* pArgs ){
    delete ((JavaVMInitArgs*)pArgs)->options[0].optionString;
    delete ((JavaVMInitArgs*)pArgs)->options;
    delete pArgs;
}

/*
Static wrapper on FindClass() JNI function.
See the description in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/functions.html#wp16027
*/

int FindClass( JNIEnv*     pEnv,
               const char* szClass,
               jclass*     pClass ){

    *pClass = pEnv->FindClass( szClass );

    if(pEnv->ExceptionCheck() == JNI_TRUE){
        pEnv->ExceptionDescribe();
        return -1;
    }
    if(*pClass != NULL)
        return 0;
    else
        return -2;

}

/*
Static wrapper on GetStaticMethodID() JNI function.
See the description in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/functions.html#wp20949
*/

int GetStaticMethodID(JNIEnv*     pEnv,
                      jclass      pClass,
                      const char* szName,
                      const char* szArgs,
                      jmethodID*  pMid){

    *pMid = pEnv->GetStaticMethodID( pClass, szName, szArgs);

    if(pEnv->ExceptionCheck() == JNI_TRUE){
        pEnv->ExceptionDescribe();
        return -1;
    }

    if( *pMid != NULL )
        return 0;
    else
        return -2;
}

/*
Static wrapper on NewObjectArray() JNI function.
See the description in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/functions.html#wp21619
*/

int NewObjectArray( JNIEnv*       pEnv,
                    int           nDimension,
                    const char*   szType,
                    jobjectArray* pArray ){

    *pArray = pEnv->NewObjectArray( nDimension, pEnv->FindClass( szType ), NULL);

    if(pEnv->ExceptionCheck() == JNI_TRUE){
        pEnv->ExceptionDescribe();
        return -1;
    }

    if( pArray != NULL )
        return 0;
    else
        return -2;

}

/*
Static wrapper on CallStaticVoidMethod() JNI function.
See the description in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/functions.html#wp4796
*/

int CallStaticVoidMethod( JNIEnv*   pEnv,
                          jclass    pClass,
                          jmethodID pMid,
                          void*     pArgs){

    g_nExitCode = 0;
    pEnv->CallStaticVoidMethod( pClass, pMid, pArgs);
    if( pEnv->ExceptionCheck() == JNI_TRUE ){
        pEnv->ExceptionDescribe();
        return -1;
    }else
        return g_nExitCode;
}

/*
Static wrapper on DestroyJavaVM() JNI function.
See the description in
http://jre.sfbay/java/re/jdk/6/promoted/latest/docs/technotes/guides/jni/spec/invocation.html#destroy_java_vm
*/

int DestroyJavaVM( JavaVM* pJVM ){
    pJVM->DestroyJavaVM();
    return 0;
}