web.xml错误调试

声明：此文为转载的，感觉有用就收藏了。

在做web项目时，web.xml的配置文件，这里列出出错的地方：
<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns="http://java.sun.com/xml/ns/j2ee" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" version="2.4"
xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee   http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd">
<servlet>
   <servlet-name>DisplaySource</servlet-name>
   <display-name>DisplaySource</display-name>
   <description>display source of sample jsp pages</description>
   <servlet-class>com.telin.develop.displaytag.sample.DisplaySourceServlet</servlet-class>
</servlet>
<servlet-mapping>
   <servlet-name>DisplaySource</servlet-name>
   <url-pattern>*.source</url-pattern>
</servlet-mapping>

<taglib>
   <taglib-uri>displaytag</taglib-uri>
   <taglib-location>/WEB-INF/displaytag.tld</taglib-location>
</taglib>
</web-app>

出现错误，如下：
1）.Severity and Description Path Resource Location Creation Time Id
cvc-complex-type.2.4.a: Invalid content was found starting with element 'display-name'.
One of '{"http://java.sun.com/xml/ns/j2ee":servlet-class,
"http://java.sun.com/xml/ns/j2ee":jsp-file}'
is expected. daiweihzdx/WebRoot/WEB-INF web.xml
2）.Severity and Description Path Resource Location Creation Time Id
cvc-complex-type.2.4.a:
Invalid content was found starting with element 'taglib'.
One of '{"http://java.sun.com/xml/ns/j2ee":description,
"http://java.sun.com/xml/ns/j2ee":display-name,
"http://java.sun.com/xml/ns/j2ee":icon,
"http://java.sun.com/xml/ns/j2ee":distributable,
"http://java.sun.com/xml/ns/j2ee":context-param,
"http://java.sun.com/xml/ns/j2ee":filter,
"http://java.sun.com/xml/ns/j2ee":filter-mapping,
"http://java.sun.com/xml/ns/j2ee":listener,
"http://java.sun.com/xml/ns/j2ee":servlet,
"http://java.sun.com/xml/ns/j2ee":servlet-mapping,
"http://java.sun.com/xml/ns/j2ee":session-config,
"http://java.sun.com/xml/ns/j2ee":mime-mapping,
   "http://java.sun.com/xml/ns/j2ee":welcome-file-list,
   "http://java.sun.com/xml/ns/j2ee":error-page,
    "http://java.sun.com/xml/ns/j2ee":jsp-config,
    "http://java.sun.com/xml/ns/j2ee":security-constraint,
    "http://java.sun.com/xml/ns/j2ee":login-config,
    "http://java.sun.com/xml/ns/j2ee":security-role,
    "http://java.sun.com/xml/ns/j2ee":env-entry,
     "http://java.sun.com/xml/ns/j2ee":ejb-ref,
     "http://java.sun.com/xml/ns/j2ee":ejb-local-ref,
     "http://java.sun.com/xml/ns/j2ee":service-ref,
      "http://java.sun.com/xml/ns/j2ee":resource-ref,
      "http://java.sun.com/xml/ns/j2ee":resource-env-ref,
      "http://java.sun.com/xml/ns/j2ee":message-destination-ref,
       "http://java.sun.com/xml/ns/j2ee":message-destination,
        "http://java.sun.com/xml/ns/j2ee":locale-encoding-mapping-list}' is expected.
        daiweihzdx/WebRoot/WEB-INF web.xml

下面列出解决办法
1）去掉：
   <display-name>DisplaySource</display-name>
   <description>display source of sample jsp pages</description>
2）把：
<taglib>
   <taglib-uri>displaytag</taglib-uri>
   <taglib-location>/WEB-INF/displaytag.tld</taglib-location>
</taglib>
放在：
<jsp-config></jsp-config>标签之中

分析：
出现错误的原因：通常是由于标签位置，标签DTD的校验规则所影响的，
所以上述问题还有如下解决办法

3）.删除“http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd”即不采用该校验规则
4）.把头文件中的“version="2.4"”改为“version="2.5"”
“http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd”改为“http://java.sun.com/xml/ns/j2ee/web-app_2_5.xsd”
即采用jsp2.5的校验规则