Java 将字符串动态生成字节码的实现方法

  boolean result = task.call();
  if (result) {
   ClassLoader loader = Thread.currentThread().getClass()
     .getClassLoader();
   try {
    Class<?> clazz = loader.loadClass(className);
    Method method = clazz.getMethod(methodName, new Class<?>[] {});
    Object value = method.invoke(null, new Object[] {});
    return (Double)value;
   } catch (Exception e) {
    // throw new CalculationException("内部错误。");
   }
  } else {
   // / new CalculationException("错误的表达式。");
  }
  return 0;
}