字符串长度不同于Javascript到Java代码 [英] String length differs from Javascript to Java code
问题描述
我有一个JSP页面，其中包含一段Javascript验证码，限制了提交时的一定数量的字符。我正在使用< textarea> 所以我不能简单地使用长度属性，例如< input type =text> ; 。
I've got a JSP page with a piece of Javascript validation code which limits to a certain amount of characters on submit. I'm using a <textarea> so I can't simply use a length attribute like in a <input type="text">.
我使用 document.getElementById（text）。value.length 获取字符串长度。我在Windows上运行Firefox 3.0（但我也用IE 6测试了这种行为）。表单将提交给J2EE servlet。在我的Java servlet中，参数的字符串长度大于2000！
I use document.getElementById("text").value.length to get the string length. I'm running Firefox 3.0 on Windows (but I've tested this behavior with IE 6 also). The form gets submitted to a J2EE servlet. In my Java servlet the string length of the parameter is larger than 2000!
我注意到这可以通过在<$ c $中添加回车来轻松复制C>< TextArea> 。我已经使用Firebug来断言< textare> 的长度，它实际上是2000个字符长。但是在Java方面，回车符转换为UNIX样式（ \\\\ n ，而不是 \ n ），因此字符串长度不同！
I've noticed that this can easily be reproduced by adding carriage returns in the <textarea>. I've used Firebug to assert the length of the <textare> and it really is 2000 characters long. On the Java side though, the carriage returns get converted to UNIX style (\r\n, instead of \n), thus the string length differs!
我错过了这里明显的东西或什么？如果没有，你如何可靠（跨平台/浏览器）确保< textarea> 是有限的。
Am I missing something obvious here or what ? If not, how would you reliably (cross-platform / browser) make sure that the <textarea> is limited.
推荐答案
这不是一个JavaScript（或Java）问题 - 两个层都报告了他们正在处理的字符串的准确长度用。你的情况下的问题是在HTTP传输过程中字符串被转换。
This isn't really a JavaScript (or Java) problem - both layers report an accurate length for the string they are dealing with. The problem in your case is that the string gets transformed during the HTTP transmission.
如果你绝对必须确保字符串不超过一定长度，你可以模仿在客户端进行此转换，将\ n的每个实例替换为\ n \\\ - 但仅用于长度验证目的：
If you absolutely must ensure that the string doesn't exceed a certain length, you can mimic this transformation on the client by replacing every instance of "\n" with "\n\r" - but only for length verification purposes:
textarea.value.replace(/\n/g, "\r\n").length
这篇关于字符串长度不同于Javascript到Java代码的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
