<form name="form1" method="post" action="test_option.jsp">
<p>
<select name="select">
<option value="1">1111</option>
<option value="2">2222</option>
<option value="3">3333</option>
<option value="4">4444</option>
</select>
</p>
<p>
<input type="submit" name="Submit" value="Submit">
</p>
</form>
<%
String option=request.getParameter("select");
if ("1".equals(option))
out.println(option);
%>
<p>
<select name="select">
<option value="1">1111</option>
<option value="2">2222</option>
<option value="3">3333</option>
<option value="4">4444</option>
</select>
</p>
<p>
<input type="submit" name="Submit" value="Submit">
</p>
</form>
<%
String option=request.getParameter("select");
if ("1".equals(option))
out.println(option);
%>
改成
if (option.equal("1"))
String option=request.getParameter("select");
if (String 1.equals(option))
out.println(option);