//form表单部分
<form action="Check_Login.jsp" method="post" name="check_login_info" onSubmit="return check(this)">
<table width="100%" border="0" class="bodystyle">
<tr>
<td colspan="3"> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td width="35%" class="wahfengmid"><div align="right"></div></td>
<td width="58%"> </td>
<td width="7%"> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right" class="wahfengmid">管理帐号:</div></td>
<td>
<input name="usr_id" type="text" id="usr_id" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="24"></td>
<td> </td>
</tr>
<tr>
<td><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td><div align="right" class="wahfengmid">管理密码:</div></td>
<td>
<input name="usr_pwd" type="password" id="usr_pwd" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="24"></td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr>
<td><div align="right"><span class="wahfengmid">验 证 码:</span></div></td>
<td>
<div align="left">
<input name="my_check_t" type="text" id="my_check_t" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="10" maxlength="8">
<span class="unnamed1">
<%
int number=(int)(Math.random()*1000000)+1;
out.print(number);%>
<input name="my_check_h" type="hidden" id="my_check_h" value="<%=number%>">
</span> </div></td>
<td> </td>
</tr>
<tr>
<td colspan="3"> </td>
</tr>
<tr>
<td colspan="3"><div align="center" class="wahfengmid">
<p>
<input type="submit" name="Submit" value="点击进入管理系统" style="background-image: url('images/Button_bg.jpg'); font-weight: bold">
</p>
</div></td>
</tr>
</table>
</form><///判断页面
<%
String checkt,checkh;
checkt=request.getParameter("my_check_t");
checkh=request.getParameter("my_check_h");
if(checkt!=checkh);
{
out.print("<script>window.alert('验证码不正确');window.location.href='index.jsp'</script>");
}
%>
<form action="Check_Login.jsp" method="post" name="check_login_info" onSubmit="return check(this)">
<table width="100%" border="0" class="bodystyle">
<tr>
<td colspan="3"> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td width="35%" class="wahfengmid"><div align="right"></div></td>
<td width="58%"> </td>
<td width="7%"> </td>
</tr>
<tr>
<td class="wahfengmid"><div align="right" class="wahfengmid">管理帐号:</div></td>
<td>
<input name="usr_id" type="text" id="usr_id" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="24"></td>
<td> </td>
</tr>
<tr>
<td><div align="right"></div></td>
<td> </td>
<td> </td>
</tr>
<tr>
<td><div align="right" class="wahfengmid">管理密码:</div></td>
<td>
<input name="usr_pwd" type="password" id="usr_pwd" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="24"></td>
<td> </td>
</tr>
<tr>
<td> </td>
<td> </td>
<td> </td>
</tr>
<tr>
<td><div align="right"><span class="wahfengmid">验 证 码:</span></div></td>
<td>
<div align="left">
<input name="my_check_t" type="text" id="my_check_t" style="background-image: url('images/pwd_bg.jpg'); color: #FF0000" size="10" maxlength="8">
<span class="unnamed1">
<%
int number=(int)(Math.random()*1000000)+1;
out.print(number);%>
<input name="my_check_h" type="hidden" id="my_check_h" value="<%=number%>">
</span> </div></td>
<td> </td>
</tr>
<tr>
<td colspan="3"> </td>
</tr>
<tr>
<td colspan="3"><div align="center" class="wahfengmid">
<p>
<input type="submit" name="Submit" value="点击进入管理系统" style="background-image: url('images/Button_bg.jpg'); font-weight: bold">
</p>
</div></td>
</tr>
</table>
</form><///判断页面
<%
String checkt,checkh;
checkt=request.getParameter("my_check_t");
checkh=request.getParameter("my_check_h");
if(checkt!=checkh);
{
out.print("<script>window.alert('验证码不正确');window.location.href='index.jsp'</script>");
}
%>
==比较是指2个对象是同一个对象(指向同一块内存)