Question

我正在使用JNI从C ++访问Java类，但只要我在java文件中调用某个方法，FindClass总是返回nil（参见java代码）。当我删除呼叫时，它可以正常工作。

./ testjnisamplecode

结果：在java代码中使用graph = new OrientGraphNoTx(odb); ...

No !

结果：在java代码中没有graph = new OrientGraphNoTx(odb); ...

Yes !

Initializing graph ..

使用命令行的Java，它工作正常：

java -cp "/mypath/orientdb/debug/orientdb-c/lib/*:." Inserter

结果：

Initializing graph .. 
Initialized ok ..

C ++

#include <string.h>
#include <stdio.h>
#include <jni.h>

void main()
{

  JavaVM *vm;
  JNIEnv *env;
  JavaVMInitArgs vm_args;

  JavaVMOption opts[2];
  opts[0].optionString = "-Djava.class.path=/mypath/orientdb/debug/orientdb-c:/mypath/orientdb/debug/orientdb-c/lib:/mypath/orientdb/debug/orientdb-c/lib/blueprints-core-2.5.0-SNAPSHOT.jar:/mypath/orientdb/debug/orientdb-c/lib/blueprints-orient-graph-2.5.0-SNAPSHOT.jar:.";
  opts[1].optionString = "-verbose:jni";   

  vm_args.version = JNI_VERSION_1_2;
  vm_args.nOptions = 0;
  vm_args.ignoreUnrecognized = 1;

  jmethodID mid;
  jint square;

  // Construct a VM
  jint res = JNI_CreateJavaVM(&vm, (void **)&env, &vm_args);

  // First get the class that contains the method you need to call
  jclass clazz = (*env)->FindClass(env, "Inserter");

  // TEST IF CLASS WAS FOUND
  if (clazz) {
    printf("Yes !\n");
  }
  else {
    printf("No !\n");
    exit(1);
  }

  // get init method
  jmethodID init = (*env)->GetMethodID(env, clazz, "<init>",
                                 "()V");

}

爪哇

import java.io.IOException;

import com.tinkerpop.blueprints.impls.orient.OrientGraphNoTx;
import com.orientechnologies.orient.core.db.graph.OGraphDatabase;
import com.tinkerpop.blueprints.TransactionalGraph;
//import com.tinkerpop.blueprints.impls.orient.OrientGraph;

import java.util.List;
import com.orientechnologies.orient.core.record.impl.ODocument;
import com.orientechnologies.orient.core.sql.query.OSQLSynchQuery;
import com.orientechnologies.orient.core.metadata.schema.OType;

public class Inserter
{
    private OGraphDatabase odb;
    private OrientGraphNoTx graph;

    public Inserter() 
    {
        System.out.println("Initializing graph .. ");

        odb = new OGraphDatabase("local:/home/vagrant/orientdb-graphed-1.5.1/databases/sitepoint-ruby-demo").open("admin","admin");

        //graph = new OrientGraphNoTx(odb);    // <----- THIS BREAKS C++ CODE

        //System.out.println("Initialized ok .. ");

    }

    public static void main(String[] args)
    {
        Inserter ins = new Inserter();
    }
}

我该如何解决这个问题？有什么想法吗？

Answer 1

我认为错过了classpath中的orientdb jar，是不够的蓝图api，你还需要包括orient-commons.jar和orientdb-core.jar（blueprints-orient-graph dependencies）

再见

JNI来自C ++，FindClass＆amp; amp;进口

1 个答案: