从Textarea读取时不保留换行符 [英] Newline not preserved when reading from Textarea

问题描述

我的Java Web应用程序从文本区域获取内容，并通过电子邮件发送内容.

My java webapp fetches content from a textarea, and e-mails the same.

我面临的问题是，使用

request.getParameter("message");

有什么线索可以解决吗?

Any clues how it can be tackled?

TIA.

文本区域中的内容是:
abcd
abcd

The content in the textarea is:
abcd
abcd

代码:

String message = request.getParameter("message");

        System.out.println("index loc for message "+message+" using \\r\\n : "+message.indexOf("\r\n"));
        System.out.println("index loc for message "+message+" using \\n : "+message.indexOf("\n"));
        System.out.println("index loc for message "+message+" using \\r : "+message.indexOf("\r"));
        System.out.println("index loc for message "+message+" using \\n\\r : "+message.indexOf("\n\r"));

输出:

使用\ r \ n的邮件asdfasdf的索引位置:-1
使用\ n的消息asdfasdf的索引位置:-1
使用\ r的消息asdfasdf的索引位置:-1
使用\ n \ r:-1

index loc for message asdfasdf using \r\n : -1
index loc for message asdfasdf using \n : -1
index loc for message asdfasdf using \r : -1
index loc for message asdfasdf using \n\r : -1

推荐答案

这完全取决于您重新显示它的方式.

That completely depends on how you're redisplaying it.

听起来您正在用HTML重新显示它. 原始"换行符不是HTML标记的一部分.右键单击Web浏览器中的查看页面源文件.您会在所有地方看到换行符.通常在HTML标记之前和/或之后.

It sounds like that you're redisplaying it in HTML. "Raw" newlines are not part of HTML markup. Do a rightclick, View Page Source in webbrowser. You'll see linebreaks over all place. Usually before and/or after HTML tags.

为了在HTML演示文稿中直观地显示换行符，您实际上应该使用<br>标记.您可以使用<br>字符串替换换行符，如下所示:

In order to visually present linebreaks in the HTML presentation, you should actually be using <br> tags. You can replace newlines by <br> strings as below:

message = message.replace("\n", "<br>");

这仅对 XSS攻击孔敏感，如果message是一个用户控制的变量，因为您必须在JSP中不转义地显示它(即不带<c:out>)，以使<br>正常工作.因此，您需要确保message变量为

This is only sensitive to XSS attack holes if the message is an user-controlled variable, because you have to present it unescaped in JSP (i.e. without <c:out>) in order to get <br> to work. You thus need to make sure that the message variable is sanitized beforehand.

或者，您也可以在此处将CSS white-space属性设置为将消息重新显示为pre的位置.如果要将行换行到block元素的上下文中，请设置pre-wrap.或者，如果您也想折叠空格和制表符，请设置pre-line.

Alternatively, you can also set CSS white-space property there where you're redisplaying the message to pre. If you'd like to wrap lines inside the context of a block element, then set pre-wrap. Or if you'd like to collapse spaces and tabs as well, then set pre-line.

<div id="message"><c:out value="${message}" /></div>

#message {
    white-space: pre-line;
}

这将显示预格式化的文本(默认情况下为文本区域).

This will display the text preformatted (as a textarea by default does).

这篇关于从Textarea读取时不保留换行符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！