02. 将异常堆栈信息，返回给前台，便于排查问题.

@RequestMapping("UserController/register")
@ResponseBody
public Map<Object, Object> register(String email, String userName, String password) {
	HashMap<Object, Object> result = MethodReturn.returnMapDefault();
	try {
		// result = userService.register(email, userName, password);
		int a = 1 / 0;
	} catch (Exception e) {
		e.printStackTrace();
		/*********************************未便于展示，暂为封装******************************************/
		Map<Object, String> exceptionStatckTrace = new LinkedHashMap<>();
		exceptionStatckTrace.put(0, e.getClass().getName() + ": " + e.getMessage());
		StackTraceElement[] stackTrace = e.getStackTrace();
		int length = stackTrace.length;
		StackTraceElement obj = null;
		StringBuilder fileName = null;
		for (int i = 0; i < length; i++) {
			obj = stackTrace[i];
			fileName = new StringBuilder();
			if (obj.getFileName() != null) {
				fileName.append(obj.getFileName());
				if (obj.getLineNumber() != -1) {
					fileName.append(": " + obj.getLineNumber());
				}
			} else {
				fileName.append("Unknown Source");
			}
			exceptionStatckTrace.put(i + 1, obj.getClassName() + "." + obj.getMethodName() + "(" + fileName.toString() + ")");
		}
		/***************************************************************************/
		result.put("exception", exceptionStatckTrace);
	} finally {
		return result;
	}
}