检测 Java 是否运行在64bit 的JVM上的方法

   public static boolean is64BitVM() {  
      String bits = System.getProperty("sun.arch.data.model");  
      if (bits != null) {  
         return bits.equals("64");  
      } else {  
         // probably sun.arch.data.model isn't available  
         // maybe not a Sun JVM?  
         // try with the vm.name property  
         return System.getProperty("java.vm.name").contains("64");  
      }   
    }