.jsp 文件
<html>
<body>
<form method="post" action="index.jsp" />
<%
String integer = request.getParameter("integer");
%>
<%
int x = 0;
try { x = Integer.parseInt("integer"); }
catch (Exception e) { x = 0; }
%>
<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />
</form>
</body>
</html>
每次点击提交按钮时，如何添加或增加 x 输出？
Integer.parseInt("integer"); -> "integer" string is not a number therefore it will be a wrong format.
并且您每次都在初始化 x = 0 并且 x 没有增量
你可以试试这个：
<form method="post" action="" />
<%
String integer = request.getParameter("integer");
int x = integer != null ? Integer.parseInt(integer) : 0;
++x;
%>
<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />
<html>
<body>
<form method="post" action="index.jsp" />
<%
String integer = request.getParameter("integer");
%>
<%
int x = 0;
try { x = Integer.parseInt("integer"); }
catch (Exception e) { x = 0; }
x = x + 1;
%>
<input type="text" name="integer" value="<%=x%>"/>
<input type="submit" value="submit" />
</form>
</body>
</html>