jsp如何限制多行文本域输入的字符个数源码，当要限制文本框的字数的时候常常会涉及的javascript脚本语言，大家也可以看到微博里的文本框字数是有限制的，那么如何使用jsp与js实现限制字数的功能呢？以下是相关的源码实例：
<%@ page contentType=”text/html; charset=gb2312″ language=”java” import=”java.sql.*” errorPage=”" %>
<html>
<head>
<meta http-equiv=”Content-Type” content=”text/html; charset=gb2312″>
<link href=”./Css/style.css” rel=”stylesheet”>
<title>限制多行文本域输入的字符个数</title>
</head>
<script language=”javascript”>
function check(){
if(form1.content.value==”"){
alert(“留言内容不允许为空！”);form1.content.focus();return;
}
form1.submit();
}
</script>
<SCRIPT language=JavaScript>
<!–
var LastCount =0;
function CountStrByte(Message,Total,Used,Remain){ //字节统计
var ByteCount = 0;
var StrValue = Message.value;
var StrLength = Message.value.length;
var MaxValue = Total.value;
if(LastCount != StrLength) { // 在此判断，减少循环次数
for (i=0;i<StrLength;i++){
ByteCount = (StrValue.charCodeAt(i)<=256) ? ByteCount + 1 : ByteCount + 2;
if (ByteCount>MaxValue) {
Message.value = StrValue.substring(0,i);
alert(“留言内容最多不能超过 ” +MaxValue+ ” 个字节！\n注意：一个汉字为两字节。”);
ByteCount = MaxValue;
break;
}
}
Used.value = ByteCount;
Remain.value = MaxValue – ByteCount;
LastCount = StrLength;
}
}
//–>
</SCRIPT>
<body>
<DIV id=toolTipLayer style=”VISIBILITY: hidden; POSITION: absolute”></DIV>
<table width=”777″ height=”341″ border=”0″ align=”center” cellpadding=”-2″ cellspacing=”-2″>
<tr>
<td valign=”top”><table width=”100%” height=”47″ border=”0″ cellpadding=”-2″ cellspacing=”-2″ class=”tableBorder”>
<tr bgcolor=”#9CA6C6″>
<td height=”8″></td>
</tr>
<tr>
<td></td>
</tr>
<tr>
<td height=”2″></td>
</tr>
<tr>
<td valign=”top”>
<table width=”100%” height=”205″ border=”0″ cellpadding=”-2″ cellspacing=”-2″ class=”tableBorder”>
<tr>
<td width=”13″ height=”32″ background=”Images/board_left.gif”> </td>
<td width=”689″ background=”Images/board_left.gif” style=”color:#FFFFFF”> ≡ 签写留言
≡ </td>
<td width=”73″ background=”Images/board_right.gif”> </td>
</tr>
<tr valign=”top”>
<td height=”171″ colspan=”3″><table width=”100%” height=”129″ border=”0″ cellpadding=”-2″ cellspacing=”-2″>
<tr>
<td valign=”top”>
<table width=”100%” height=”292″ border=”0″ cellpadding=”-2″ cellspacing=”-2″ class=”tableBorder_Top”>
<tr>
<td height=”5″></td>
</tr>
<tr>
<td width=”236″ height=”263″ valign=”top”><div align=”center”>
<p>
=== 留言人信息 ===<br>
城中狼</p>
<p>我是：男生</p>
<p>
<img src=”Images/email.gif” alt=”的Email是：” width=”16″ height=”16″> ********</p>
<p>
<img src=”Images/oicq.gif” alt=”的QQ号码是：” width=”16″ height=”16″> QQ:*********</p>
<p>
<img src=”Images/ip.gif” alt=”IP为：” width=”16″ height=”15″> IP：192.168.1.122</p>
</div></td>
<td width=”1″ background=”Images/line.gif”></td>
<td width=”532″ valign=”top”>
<form action=”" method=”post” name=”form”>
<table width=”100%” border=”0″ cellspacing=”-2″ cellpadding=”-2″>
<tr>
<td width=”11%” height=”90″ align=”center”>表情：</td>
<td width=”89%”><INPUT name=emote type=radio class=”noborder” value=0 checked>
<IMG height=20
src=”Images/Face/face0.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=1>
<IMG height=19
src=”Images/Face/face1.gif” width=19 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=2>
<IMG height=20
src=”Images/Face/face2.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=3>
<IMG height=20
src=”Images/Face/face3.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=4>
<IMG height=20
src=”Images/Face/face4.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=5>
<IMG height=20
src=”Images/Face/face5.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=6>
<IMG height=20
src=”Images/Face/face6.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=7>
<img height=20
src=”Images/Face/face7.gif” width=20 align=middle border=0><br>
<INPUT name=emote type=radio class=”noborder” value=8>
<IMG height=20
src=”Images/Face/face8.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=9>
<IMG height=20
src=”Images/Face/face9.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=10>
<IMG height=20
src=”Images/Face/face10.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=11>
<IMG height=20
src=”Images/Face/face11.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=12>
<IMG height=20
src=”Images/Face/face12.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=13>
<IMG height=20
src=”Images/Face/face13.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=14>
<IMG height=20
src=”Images/Face/face14.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=15>
<img height=20
src=”Images/Face/face15.gif” width=20 align=middle border=0><br>
<INPUT name=emote type=radio class=”noborder” value=16>
<IMG height=20
src=”Images/Face/face16.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=17>
<IMG height=20
src=”Images/Face/face17.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=18>
<IMG height=20
src=”Images/Face/face18.gif” width=20 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=19>
<IMG height=19
src=”Images/Face/face19.gif” width=19 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=20>
<IMG height=19
src=”Images/Face/face20.gif” width=19 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=21>
<IMG height=19
src=”Images/Face/face21.gif” width=19 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=22>
<IMG height=19
src=”Images/Face/face22.gif” width=19 align=middle border=0>
<INPUT name=emote type=radio class=”noborder” value=23>
<IMG height=19
src=”Images/Face/face23.gif” width=19 align=middle border=0></td>
</tr>
<tr>
<td height=”145″ align=”center”>留言：</td>
<td><textarea name=”content” cols=”50″ rows=”9″ class=”wenbenkuang” id=”content” onkeydown=”CountStrByte(this.form.content,this.form.total,this.form.used,this.form.remain);”
onkeyup=”CountStrByte(this.form.content,this.form.total,this.form.used,this.form.remain);”></textarea></td>
</tr>
<tr>
<td height=”33″ align=”center” style=”padding-left:10px”><p>字节：</p> </td>
<td style=”padding-left:10px” class=”word_grey”>最多允许
<input name=”total” type=”text” disabled class=”noborder” id=”total” value=”1600″ size=”4″>
个字节 已用字节：
<input name=”used” type=”text” disabled class=”noborder” id=”used” value=”0″ size=”4″>
剩余字节：
<input name=”remain” type=”text” disabled class=”noborder” id=”remain” value=”1600″ size=”4″>
<input name=”HIP” type=”hidden” id=”HIP” value=”"></td>
</tr>
<tr>
<td height=”34″ align=”center” style=”padding-left:10px”> </td>
<td class=”word_grey”><input name=”Button” type=”button” class=”btn_grey” value=”提交留言”>
<input name=”Submit2″ type=”reset” class=”btn_grey” value=”重写留言”></td></tr>
</table>
</form>
</td>
</tr>
<tr>
<td valign=”top”></td>
<td background=”Images/line.gif”></td>
<td> </td>
</tr>
<tr>
<td height=”5″></td>
</tr>
</table> </td>
</tr>
</table>
</td>
</tr>
</table>
</td>
</tr>
</table>
<table width=”777″ height=”89″ border=”0″ align=”center” cellpadding=”-2″ cellspacing=”-2″>
<tr>
<td align=”center”><div align=”center” style=”color:#666666 “>本站请用IE5.0或以上版本浏览，1024*768为最佳效果<br>
CopyRight © 2005 长春市明日实业有限公司</div></td>
</tr>
</table>
</body>
</html>