java - jsp中检查参数是否有效

Question

我只想检查传递给jsp的参数是否为空或不使用httpcontext，所以我怎么能做到这一点

case_yr = Integer.parseInt(request.getParameter("case_yr"));
sub_type_int =Integer.parseInt(request.getParameter("sub_type_int"));
String case_num = request.getParameter("case_num");
String lang_mode = request.getParameter("lang_mode");
String mobile_no = request.getParameter("caller_id");
String dialled_id = request.getParameter("dialled_id");

我想上面的值是否有效我正在将值从 xml 页面提交到 jsp 页面并在 jsp 中使用request.getparameter()

所以请告诉如何检查值是否为空，并且没有 sevlet 只有 vxml 页面和 jsp 页面

Answer 1

You can use following code to check for valid parameter.

String value = request.getParameter("case_yr")
if(value != null)
   case_yr = Integer.parseInt(value );

String value1 = request.getParameter("sub_type_int");
if(value1 != null)
   sub_type_int =Integer.parseInt(value1 );

Answer 2

Use JSTL

<c:if test="${not empty case_num}">
    case_num is NOT empty or null.
</c:if>

Answer 3

如果您想检查请求属性是否是null，只需检查它们是否是null这种方式

String case_num = request.getParameter("case_num");
if(case_num!=null){
    //do your logic
 }
 else {
  System.out.println("case_num is null");
  }
 int number ;
String num = request.getParameter(num);
 if(num!=null){
     number = Integer.parseInt(num);
   }
 else {
  System.out.println("case_num is null");
  }