Java example source code file (invoker.cs)

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Java - Java tags/keywords

callstaticvoidmethod, destroyjavavm, dllimport, error, findclass, freejavavminitargs, getstaticmethodid, invokemain, jni_createjavavm, jvm, makejavavminitargs, newobjectarray, string, the

The invoker.cs Java example source code

/*
 * Copyright (c) 2006, 2008, 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.
 */

/*
*/

using System;
using System.Runtime.InteropServices;

class jinvoker{

    public static int Main(string[] aArgs){
        
        // Print Hello to show we are in CLR
        Console.WriteLine("Hello from C#");
        if(aArgs.Length > 0)
            // invoke JVM
            return InvokeMain(aArgs[0]);
        else
            return -1;
    }

    // Link the JVM API functions and the wrappers

    [DllImport("jvm.dll")]      public unsafe static extern int  JNI_CreateJavaVM(void** ppVm, void** ppEnv, void* pArgs);
    [DllImport("jinvoker.dll")] public unsafe static extern int  MakeJavaVMInitArgs( void** ppArgs );
    [DllImport("jinvoker.dll")] public unsafe static extern void FreeJavaVMInitArgs( void* pArgs );
    [DllImport("jinvoker.dll")] public unsafe static extern int  FindClass( void* pEnv, String sClass, void** ppClass );
    [DllImport("jinvoker.dll")] public unsafe static extern int  GetStaticMethodID( void*  pEnv,
                                                                                    void*  pClass, 
                                                                                    String szName, 
                                                                                    String szArgs, 
                                                                                    void** ppMid);
	
    [DllImport("jinvoker.dll")] public unsafe static extern int NewObjectArray( void*  pEnv,
                                                                                int    nDimension,
                                                                                String sType,
                                                                                void** ppArray );

    [DllImport("jinvoker.dll")] public unsafe static extern int CallStaticVoidMethod( void* pEnv,
                                                                                      void* pClass,
                                                                                      void* pMid,
                                                                                      void* pArgs);

    [DllImport("jinvoker.dll")] public unsafe static extern int DestroyJavaVM( void* pJVM );

	public unsafe static int InvokeMain( String sClass ){
	    
        void*  pJVM;    // JVM struct
        void*  pEnv;    // JVM environment
        void*  pVMArgs; // VM args
        void*  pClass;  // Class struct of the executed method
        void*  pMethod; // The executed method struct
        void*  pArgs;   // The executed method arguments struct

        // Fill the pVMArgs structs
        MakeJavaVMInitArgs( &pVMArgs );

        // Create JVM
        int nRes = JNI_CreateJavaVM( &pJVM, &pEnv, pVMArgs );
        if( nRes == 0 ){
			
            // Find the executed method class 
            if(FindClass( pEnv, sClass, &pClass) == 0 )
				
                // Find the executed method
                if( GetStaticMethodID( pEnv, pClass, "main", "([Ljava/lang/String;)V", &pMethod ) == 0 )
					
                    // Create empty String[] array to pass to the main()
                    if( NewObjectArray( pEnv, 0, "java/lang/String", &pArgs ) == 0 ){

                        // Call main()
                        nRes = CallStaticVoidMethod( pEnv, pClass, pMethod, pArgs );
                        if( nRes != -1 )
                            Console.WriteLine("Result:"+nRes);
                        else
                            Console.WriteLine("Exception");
                        
                    }else{
                        Console.WriteLine("Error while making args array");
                        nRes = -100;
                    }
                else{
                    Console.WriteLine("can not find method main(String[])");
                    nRes = -101;
                }
            else{
                Console.WriteLine("can not find class:"+sClass);
                nRes = -102;
            }
			
            // Destroy the JVM
            DestroyJavaVM( pJVM );

        }else
            Console.WriteLine("Can not create Java VM");

        // Free the JVM args structs
        FreeJavaVMInitArgs(pVMArgs);
		
        return nRes;
    }
}