tomcat:去掉jsp中的空白行或空白
一般在jsp头部有至少一行空白,是因为
<%@ page language="java" contentType="text/html; charset=utf-8" pageEncoding="utf-8"%>
引起的，如果还有其它的标签引入或类引入会出现更多的空白.例如:
<%@ page import="..."%> <%@ taglib prefix="xxx" uri=".tld"%> <%@ taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core"%>
查看源码后如图:
为什么容不下空白?有几行空白有什么不好?
1.响应内容会更大,比没有空白或空行的
2.如果要解析响应内容要多哪么几行代码
3.我们眼中容不下空白,
怎么去掉它呢?
1.坏办法:一一把jsp头部或可能出现空白的行打到一行上，这样再次编辑或打开时不易查看
2.简单了:在tomcat的conf/web.xml中的org.apache.jasper.servlet.JspServlet servlet 增加几个参数,这是默认的配置（取自7.0.55）
<!-- The JSP page compiler and execution servlet, which is the mechanism -->
<!-- used by Tomcat to support JSP pages. Traditionally, this servlet -->
<!-- is mapped to the URL pattern "*.jsp". This servlet supports the -->
<!-- following initialization parameters (default values are in square -->
<!-- brackets): -->
<!-- -->
<!-- checkInterval If development is false and checkInterval is -->
<!-- greater than zero, background compilations are -->
<!-- enabled. checkInterval is the time in seconds -->
<!-- between checks to see if a JSP page (and its -->
<!-- dependent files) needs to be recompiled. [0] -->
<!-- -->
<!-- classdebuginfo Should the class file be compiled with -->
<!-- debugging information? [true] -->
<!-- -->
<!-- classpath What class path should I use while compiling -->
<!-- generated servlets? [Created dynamically -->
<!-- based on the current web application] -->
<!-- -->
<!-- compiler Which compiler Ant should use to compile JSP -->
<!-- pages. See the jasper documentation for more -->
<!-- information. -->
<!-- -->
<!-- compilerSourceVM Compiler source VM. [1.6] -->
<!-- -->
<!-- compilerTargetVM Compiler target VM. [1.6] -->
<!-- -->
<!-- development Is Jasper used in development mode? If true, -->
<!-- the frequency at which JSPs are checked for -->
<!-- modification may be specified via the -->
<!-- modificationTestInterval parameter. [true] -->
<!-- -->
<!-- displaySourceFragment -->
<!-- Should a source fragment be included in -->
<!-- exception messages? [true] -->
<!-- -->
<!-- dumpSmap Should the SMAP info for JSR45 debugging be -->
<!-- dumped to a file? [false] -->
<!-- False if suppressSmap is true -->
<!-- -->
<!-- enablePooling Determines whether tag handler pooling is -->
<!-- enabled. This is a compilation option. It will -->
<!-- not alter the behaviour of JSPs that have -->
<!-- already been compiled. [true] -->
<!-- -->
<!-- engineOptionsClass Allows specifying the Options class used to -->
<!-- configure Jasper. If not present, the default -->
<!-- EmbeddedServletOptions will be used. -->
<!-- -->
<!-- errorOnUseBeanInvalidClassAttribute -->
<!-- Should Jasper issue an error when the value of -->
<!-- the class attribute in an useBean action is -->
<!-- not a valid bean class? [true] -->
<!-- -->
<!-- fork Tell Ant to fork compiles of JSP pages so that -->
<!-- a separate JVM is used for JSP page compiles -->
<!-- from the one Tomcat is running in. [true] -->
<!-- -->
<!-- genStringAsCharArray -->
<!-- Should text strings be generated as char -->
<!-- arrays, to improve performance in some cases? -->
<!-- [false] -->
<!-- -->
<!-- ieClassId The class-id value to be sent to Internet -->
<!-- Explorer when using <jsp:plugin> tags. -->
<!-- [clsid:8AD9C840-044E-11D1-B3E9-00805F499D93] -->
<!-- -->
<!-- javaEncoding Java file encoding to use for generating java -->
<!-- source files. [UTF8] -->
<!-- -->
<!-- keepgenerated Should we keep the generated Java source code -->
<!-- for each page instead of deleting it? [true] -->
<!-- -->
<!-- mappedfile Should we generate static content with one -->
<!-- print statement per input line, to ease -->
<!-- debugging? [true] -->
<!-- -->
<!-- maxLoadedJsps The maximum number of JSPs that will be loaded -->
<!-- for a web application. If more than this -->
<!-- number of JSPs are loaded, the least recently -->
<!-- used JSPs will be unloaded so that the number -->
<!-- of JSPs loaded at any one time does not exceed -->
<!-- this limit. A value of zero or less indicates -->
<!-- no limit. [-1] -->
<!-- -->
<!-- jspIdleTimeout The amount of time in seconds a JSP can be -->
<!-- idle before it is unloaded. A value of zero -->
<!-- or less indicates never unload. [-1] -->
<!-- -->
<!-- modificationTestInterval -->
<!-- Causes a JSP (and its dependent files) to not -->
<!-- be checked for modification during the -->
<!-- specified time interval (in seconds) from the -->
<!-- last time the JSP was checked for -->
<!-- modification. A value of 0 will cause the JSP -->
<!-- to be checked on every access. -->
<!-- Used in development mode only. [4] -->
<!-- -->
<!-- recompileOnFail If a JSP compilation fails should the -->
<!-- modificationTestInterval be ignored and the -->
<!-- next access trigger a re-compilation attempt? -->
<!-- Used in development mode only and is disabled -->
<!-- by default as compilation may be expensive and -->
<!-- could lead to excessive resource usage. -->
<!-- [false] -->
<!-- -->
<!-- scratchdir What scratch directory should we use when -->
<!-- compiling JSP pages? [default work directory -->
<!-- for the current web application] -->
<!-- -->
<!-- suppressSmap Should the generation of SMAP info for JSR45 -->
<!-- debugging be suppressed? [false] -->
<!-- -->
<!-- trimSpaces Should white spaces in template text between -->
<!-- actions or directives be trimmed? [false] -->
<!-- -->
<!-- xpoweredBy Determines whether X-Powered-By response -->
<!-- header is added by generated servlet. [false] -->
<servlet>
<servlet-name>jsp</servlet-name>
<servlet-class>org.apache.jasper.servlet.JspServlet</servlet-class>
<init-param>
<param-name>fork</param-name>
<param-value>false</param-value>
</init-param>
<init-param>
<param-name>xpoweredBy</param-name>
<param-value>false</param-value>
</init-param>
<load-on-startup>3</load-on-startup>
</servlet>
有了conf/web.xml中的配置还不足以去掉空白,还需要在你的项目的web.xml中增加一个jsp-config
<jsp-config>
<jsp-property-group>
<url-pattern>*.jsp</url-pattern>
<trim-directive-whitespaces>true</trim-directive-whitespaces>
</jsp-property-group>
</jsp-config>
清理 ->重新编译字节码 ->发布 ->空白说:bye!
3.其它方法:留给你白渡了