方法一：

<%@ page language="java" contentType="text/html; charset=UTF-8"
    pageEncoding="UTF-8"%>
<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title>Insert title here</title>
</head>
<body>
<textarea name="" id="txt" cols="30" rows="10"></textarea>
<input type="button" id="btn" value="点击按钮">
<div id="desc"></div>
</body>
<script>
    var txt = document.getElementById('txt')
    var btn = document.getElementById('btn')
    var desc = document.getElementById('desc')
    btn.onclick = function () {
        var val = txt.value
        val = val.replace(/\r\n/g, '<br/>'); //IE9、FF、chrome
        val = val.replace(/\n/g, '<br/>'); //IE7-8
        val = val.replace(/\s/g, ' '); //空格处理
        desc.innerHTML = val;
    }
</script>
</html>

　　方法二:

步骤：
1. 用<pre><c:out value="<%=从数据库显示的字段%>"></c:out></pre>
2. 显示页面中增加：
<style type="text/css">
pre {
white-space: pre-wrap;
white-space: -moz-pre-wrap;
white-space: -pre-wrap;
white-space: -o-pre-wrap;
word-wrap: break-word;
}
</style>
原文链接：https://blog.csdn.net/moneyzhong/article/details/8820324
!!!!第二种方法很方便