Question

我正在做一个示例程序来从java调用c ++程序。我已经完成了Java JNI框架并遵循了一些示例。我正在AIX 5 powerpc系统中实现示例。这是我的java代码片段。

public class Helloworld {
  public native void helloCpp();
  public  native int getEmpId();
  public static void main(String[] args) {
    //System.loadLibrary("occidml");
    System.loadLibrary("JavaToCpp"); // shared object file.
    Helloworld hello=new Helloworld();
    System.out.println("calling c++ methods from java");
    hello.helloCpp();
    System.out.println("retrieve value from c++");
    int i_perf_obj=hello.getPerfObj();
    System.out.println("i_perf_obj value from c++ program"+i_perf_obj);
  }
}

通过编译从上面生成头文件。下面是带有OCCI数据库连接实现的c ++程序，它是从java调用的

#include <iostream>
#include "Helloworld.h"
#include <occi.h>

using namespace oracle::occi;
using namespace std;

JNIEXPORT void JNICALL Java_Helloworld_helloCpp
  (JNIEnv *, jobject)
{

  cout<<"Hello World form C++"<<endl;
  return;
}

JNIEXPORT jint JNICALL Java_Helloworld_getEmpId
  (JNIEnv *env , jobject obj)
{

  cout<<"In side c++ program";

  int empid=0;    
  cout<<"Calling OCCI method retreivePerfObj()";  

  Environment *env;
  Connection *conn;
  Statement *stmt;

  string user = "hr";
  string passwd = "admin";
  string db = "mydb:1521/mydb";

  env = Environment::createEnvironment(Environment::DEFAULT);
  cout<<"Environment Created"<<endl;
  cout<<"User:"<<user<<"\tPass:"<<passwd<<"\tDB:"<<db<<endl;
  conn = env->createConnection (user, passwd, db);
  cout<<"Connection Established"<<endl;
  string sqlStmt = "SELECT id FROM emp where emp_id=123";
  stmt = conn->createStatement (sqlStmt);
  ResultSet *rset = stmt->executeQuery ();
  try{
    while (rset->next ())
    {
      i_perf_obj=rset->getInt (1);
      cout << "i_perf_obj: "<<i_perf_obj<< "\t\t"<< endl;
    }
  }catch(SQLException ex)
  {
    cout<<"Exception thrown for displayAllRows"<<endl;
    cout<<"Error number: "<<  ex.getErrorCode() << endl;
    cout<<ex.getMessage() << endl;
  }

  stmt->closeResultSet (rset);
  conn->terminateStatement (stmt);
  cout << "Terminating the connection......" << endl;
  env->terminateConnection (conn);
  cout << "Connection Terminated" << endl;
  Environment::terminateEnvironment (env);
  cout << "Environment Terminated" << endl;

  cout<<"returning value from c++ program";
  return empid;
}


int main(){}

我使用以下命令编译了c ++程序。

   make buildocci OBJS=JavaToCpp.o EXE=JavaToCpp

    xlC -c -I/usr/appl/pmr/uat/oci-11.2.0.4.0/instantclient_11_2/sdk/include - 
    I/usr/java5/include -q64 -qlongdouble -I/usr/appl/pmr/uat/oci- 
    11.2.0.4.0/instantclient_11_2/sdk/include  JavaToCpp.cpp


    xlC -o JavaToCpp -q64 JavaToCpp.o -L/usr/appl/pmr/uat/oci-

    11.2.0.4.0/instantclient_11_2/ -locci -lclntsh

我生成了共享库，如下所示。

  xlC -q64 -G  -qmkshrobj JavaToCpp.o -o JavaToCpp.so

当我运行java程序时

java HelloWorld

我收到以下错误。

Exception in thread "main" java.lang.UnsatisfiedLinkError: 
   /usr/appl/pmr/uat/temp/jk225/JavaToCppDemo/JavaToCpp.so (Could not load module 
    /usr/appl/pmr/uat/temp/jk225/JavaToCppDemo/JavaToCpp.so.
    The module has an invalid magic number.)

    at java.lang.ClassLoader.loadLibraryWithPath(ClassLoader.java:995)
    at java.lang.System.load(System.java:441)
    at Helloworld.main(Helloworld.java:16)

任何人都可以帮我解决这个问题。

提前致谢。

使用JNI从java调用c ++程序时出现问题

0 个答案: