淺談如何刪除JSP編譯後的空行

http://blog.csdn.net/st780206/archive/2010/03/12/5372736.aspx

當你在用戶端用view source看JSP產生的程式碼時，會發現有很多空行，他們是由< %...% >後的斷行符號換行而產生的，也就是說每一行由< %...% >包含的JSP代碼到用戶端都變成一個空行，雖然不影響瀏覽，但還是希望能把他們刪掉。這裡將為大家介紹如何刪除JSP編譯後的空行。

Tomcat刪除JSP編譯後的空行辦法如下：

1. 支援JSP 2.1+ ，在每個要去空行的頁面裡包含下面代碼：

 

  
<%@ page trimDirectiveWhitespaces="true" %> 
 

在 Tomcat 6.0.14下測試JSP編譯成功

2. 支援servlet 2.5+, 即 web.xml的 XSD版本為2.5，在web.xml中加入如下代碼

 

  
<jsp-config> 
  
<jsp-property-group> 
  
<url-pattern>*.jsp</url-pattern> 
  
<trim-directive-whitespaces>true</trim-directive-whitespaces> 
  
</jsp-property-group> 
  
</jsp-config> 
 

在tomcat 6.0.14下測試JSP編譯成功

3. Tomcat 5.5.x+，在Tomcat安裝目錄/conf/web.xml中找到名叫"jsp"的servlet，添加下面一段代碼：

 

  
<init-param> 
  
<param-name>trimSpaces</param-name> 
  
<param-value>true</param-value> 
  
</init-param> 
 

本人沒測過，不過tomcat中web.xml檔案的協助這麼說的

trimSpaces          Should white spaces in template text between  actions or directives be trimmed?  [false]

在實際操作中我加入了5.5的配置到頁面中並反覆啟動了幾次tomcat但是還是沒有成功，後來才想到JSP已經編譯成servlet了所以沒有能改變，進入到tomcat中的work目錄把已經進行JSP編譯的class全部刪除，哇哈哈，整個世界清淨了，成功刪除空行

resin刪除JSP編譯後的空行辦法如下：

I'm getting a lot of whitespace in my JSP that I don't intend to be there. Why is it appearing and how can I get rid of it?

The extra whitespace is coming from newlines, often at the end of declaration lines at the beginning of the JSP. For example, the following jsp:

 

<%@ page import='java.util.*' %><%@ page import='java.io.*' %>Hello world

 

Has newlines in these locations:

 

<%@ page import='java.util.*' %>NL<%@ page import='java.io.*' %>NLHello worldNL

 

The result contains the newlines, which may be surprising:

 

Hello world

 

One solution is to let the JSP tag extend across the newline:

 

<%@ page import='java.util.*'%><%@ page import='java.io.*'%>Hello world

 

Another solution is to use JSP comments to remove the newlines:

 

<%@ page import='java.util.*' %><%----%><%@ page import='java.io.*' %><%----%>Hello world

 

Another solution is to use the XML syntax of JSP. Parsing of XML causes removal of extra whitespace.

 

<jsp:root><jsp:directive.page import="java.util.*"/><jsp:directive.page import="java.io.*"/><jsp:text>Hello world</jsp:text></jsp:root>

 

Resin also supports the use of the '/' character to eat whitespace (this is a Resin specific feature):

 

<%@ page import='java.util.*' %>/<%@ page import='java.io.*' %>/Hello world