在编写servlet时,遇到如下情况:
<web-app>
<!-- Servlet -->
<servlet>
<servlet-name>servlet</servlet-name>
<servlet-class>com.logon.src.logon</servlet-class>
<init-param>
<param-name>param</param-name>
<param-value></param-value>
</init-param>
</servlet>
<!-- Mapping -->
<servlet-mapping>
<servlet-name>servlet</servlet-name>
<url-pattern>servlet/logon</url-pattern>
</servlet-mapping>
</web-app>
如果在<param-value></param-value>
中想使用"<"字符,<param-value><</param-value>
,这样写的话
,在web服务器启动并读入web.xml信息时会发生如下错误:
[INFO] Registry - -Loading registry information
[INFO] Registry - -Creating new Registry instance
[INFO] Registry - -Creating MBeanServer
[INFO] Http11Protocol - -Coyote HTTP/1.1をポート8080で初期化します
サービス Tomcat-Standalone を起動します
Apache Tomcat/4.1.27
[INFO] PropertyMessageResources - -Initializing, config='org.apache.struts.util.LocalStrings', returnNull=true
[INFO] PropertyMessageResources - -Initializing, config='org.apache.struts.action.ActionResources', returnNull=true
[INFO] PropertyMessageResources - -Initializing, config='org.apache.webapp.admin.ApplicationResources', returnNull=true
[ERROR] Digester - -Parse Fatal Error at line 11 column 18: The content of elements must consist of well-formed character data or markup. org.xml.sax.SAXParseException: The content of elements must consist of well-formed character data or markup.
at org.apache.xerces.util.ErrorHandlerWrapper.createSAXParseException(Unknown Source)
at org.apache.xerces.util.ErrorHandlerWrapper.fatalError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLErrorReporter.reportError(Unknown Source)
at org.apache.xerces.impl.XMLScanner.reportFatalError(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl$FragmentContentDispatcher.dispatch(Unknown Source)
at org.apache.xerces.impl.XMLDocumentFragmentScannerImpl.scanDocument(Unknown Source)
at org.apache.xerces.parsers.XML11Configuration.parse(Unknown Source)
at org.apache.xerces.parsers.DTDConfiguration.parse(Unknown Source)
at org.apache.xerces.parsers.XMLParser.parse(Unknown Source)
at org.apache.xerces.parsers.AbstractSAXParser.parse(Unknown Source)
at org.apache.commons.digester.Digester.parse(Digester.java:1548)
at org.apache.catalina.startup.ContextConfig.applicationConfig(ContextConfig.java:282)
at org.apache.catalina.startup.ContextConfig.start(ContextConfig.java:639)
at org.apache.catalina.startup.ContextConfig.lifecycleEvent(ContextConfig.java:243)
at org.apache.catalina.util.LifecycleSupport.fireLifecycleEvent(LifecycleSupport.java:166)
at org.apache.catalina.core.StandardContext.start(StandardContext.java:3568)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1188)
at org.apache.catalina.core.StandardHost.start(StandardHost.java:738)
at org.apache.catalina.core.ContainerBase.start(ContainerBase.java:1188)
at org.apache.catalina.core.StandardEngine.start(StandardEngine.java:347)
at org.apache.catalina.core.StandardService.start(StandardService.java:497)
at org.apache.catalina.core.StandardServer.start(StandardServer.java:2190)
at org.apache.catalina.startup.Catalina.start(Catalina.java:512)
at org.apache.catalina.startup.Catalina.execute(Catalina.java:400)
at org.apache.catalina.startup.Catalina.process(Catalina.java:180)
at java.lang.reflect.Method.invoke(Native Method)
at org.apache.catalina.startup.Bootstrap.main(Bootstrap.java:203)
并且在servlet中使用getInitParameter("param")无法取得"<"字符,那有没有办法能在xml中写"<"呢?
其实xml中要写"<",我们可以用html的标记来标识,如下:
<param-value><</param-value>
之后我们就可以在servlet中通过getInitParameter("param")读出"<"字符了,其它一些xml中的关键字也可以通过html标签读取出来,过程如下:
1.在web.xml中定义
2.在servlet端读取