关于异常的工具类

public class Exceptions {

   /**
    * 将CheckedException转换为UncheckedException.
    */
   public static RuntimeException unchecked(Exception e) {
      if (e instanceof RuntimeException) {
         return (RuntimeException) e;
      } else {
         return new RuntimeException(e);
      }
   }

   /**
    * 将ErrorStack转化为String.
    */
   public static String getStackTraceAsString(Throwable e) {
      if (e == null){
         return "";
      }
      StringWriter stringWriter = new StringWriter();
      e.printStackTrace(new PrintWriter(stringWriter));
      return stringWriter.toString();
   }

   /**
    * 判断异常是否由某些底层的异常引起.
    */
   public static boolean isCausedBy(Exception ex, Class<? extends Exception>... causeExceptionClasses) {
      Throwable cause = ex.getCause();
      while (cause != null) {
         for (Class<? extends Exception> causeClass : causeExceptionClasses) {
            if (causeClass.isInstance(cause)) {
               return true;
            }
         }
         cause = cause.getCause();
      }
      return false;
   }

   /**
    * 在request中获取异常类
    * @param request
    * @return 
    */
   public static Throwable getThrowable(HttpServletRequest request){
      Throwable ex = null;
      if (request.getAttribute("exception") != null) {
         ex = (Throwable) request.getAttribute("exception");
      } else if (request.getAttribute("javax.servlet.error.exception") != null) {
         ex = (Throwable) request.getAttribute("javax.servlet.error.exception");
      }
      return ex;
   }
   
}