使用java调用dll时出现Unable to load library报错如何解决

public class OtherAdapter {
static
 {
  //System.loadLibrary("Connector");//载入需要调用的dll Connector.dll
  System.load("d://Connector.dll");//载入dll Connector.dll
 }
 
 //用native关键字修饰将被其它语言实现的方法
 //dll文件中对应的函数声明
 public native static int _PWLogon(String lpszDS,String lpszUser,String lpszPWD);
 //函数声明
 public native static void _PWLogout();
 public native static String _GetPWLastError();
 public native static String _GetPWFolders(long lParentFolderno);
 public native static String _GetPWDocuments(long lFolderno);
 public native static String _GetPWFiles(long lFolderno,long lDocno);
   
 //public native static String pirntStr(String msg);//函数声明
 public static void main(String[] args){
  //本地方法的调用
  int rs=_PWLogon("服务器","账号","密码");
  System.out.println("用户登录状态："+rs);
    if(rs==1)
    {
     System.out.println("获取顶级目录："+_GetPWFolders(0));
      
     System.out.println("获取父子目录："+_GetPWDocuments(54));
      
     System.out.println("下载指定文件："+_GetPWFiles(54,2));
      
     _PWLogout();
    }
    else
    {
     System.out.println("获取错误信息："+_GetPWLastError());
    }
 }
}