1---:java.lang.NoClassDefFoundError: org/apache/struts2/dojo/views/jsp/ui/HeadTag
解決辦法：原因缺少了dojo的JAR包，引入即可:struts2-dojo-plugin-2.1.2.jar
The "head" tag renders required JavaScript code to configure Dojo and is required in order to use any of the tags included in the Dojo plugin.
--------------------
If you are planning to nest tags from the Dojo plugin, make sure you set parseContent="false", otherwise each request made by the inner tags will be performed twice.
2---:Unable to load configuration. -bean -jar:file:/F:/Struts2/Struts2/WebRoot/WEB-INF/lib/struts2-core- 2.1.2.jar!/struts-default.xml:46:178
Caused by: Unable to load bean: type:org.apache.struts2.dispatcher.multipart.MultiPartRequest class:org.apache.struts2.dispatcher.multipart.JakartaMultiPartRequest -bean -jar:file:/F:/Struts2/Struts2/WebRoot/WEB-INF/lib/struts2-core-2.1.2.jar!/struts-default.xml:46:178
Caused by: java.lang.NoClassDefFoundError: org/apache/commons/fileupload/RequestContext
解決辦法：缺少JAR包，引入commons-fileupload-1.2.1.jar，commons-io-1.3.2.jar即可
3---:No tag "datetimepicker" defined in tag library imported with prefix "s"
原因版本問題：缺少struts-dojo-plugin JAR包，以及HTML的,<HEAD></HEAD>中沒有使用<s:head/>標簽
If you're using Struts 2.1.x you're probablymissing the>struts-dojo-plugin. Michal's reference below applies to Struts 2.1.xonly. In the lasts versions (since 2.0.9 I guess), all AJAX are in dojo> plugin.
> > So you need toinclude <%@ taglib uri="/struts-dojo-tags" prefix="sx"%>
> > and <sx:head/>
> >( Temp1:
<sx:datetimepicker name="picker" />
Temp2:
<sx:datetimepicker type="time" name="picker" /><br/>
Temp3:
<sx:datetimepicker value="%{'2008-06-08'}" name="picker" />
Temp4:
<sx:datetimepicker value="date" name="picker" />)
> > and call :<sx:datetimepicker .../>
4---:使用TILES框架
If you use the Tiles 2 plugin, check your tiles.xml file(s) to ensure they contain a DOCTYPE.
<!DOCTYPE tiles-definitions PUBLIC "-//Apache Software Foundation//DTD Tiles Configuration 2.0//EN" "http://tiles.apache.org/dtds/tiles-config_2_0.dtd"><tiles-definitions>
5---:struts2中不支持EL表達式
Struts2.1 tags do not allow evaluation of JSP EL within their attributes.Instead, Struts2 tags evaluate attribute values as OGNL. Allowing bothexpression languages within the same attribute opens major securityvulnerabilities.
6---文件上傳過程中取不到文件名和文件類型，即都取到NULL
原因：如果頁面中file的name=“a”則我們ACTION中設置String aContentType,String aFileName;(此兩個其實無所謂，關鍵是SET方法)
setA(File file)(){}; setAContentType(String s){};setAFileName(String name){} 即格式如下：setXContentType() setXFileName().X代表你給FILE取的NAME名字
必須和它相同，固定格式
7---嚴重: Unable to parse request
org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (8523356) exceeds the configured maximum (2097152)
at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:914)2008-5-27 17:46:51 com.opensymphony.xwork2.util.logging.commons.CommonsLogger warn
警告: Could not find property [struts.valueStack]
2008-5-27 17:46:51 com.opensymphony.xwork2.util.logging.commons.CommonsLogger error
嚴重: the request was rejected because its size (8523356) exceeds the configured maximum (2097152)
2008-5-27 17:46:51 com.opensymphony.xwork2.util.logging.commons.CommonsLogger warn
警告: Could not find property [org.apache.catalina.jsp_file]
原因：上傳文件大小超過預定大小，可以在struts.properties配置文件中設置struts.multipart.maxSize=XXX（XXX為文件大?。?br />
8---配置了文件類型限制后，當傳錯誤類型可以攔截不讓用戶上傳該文件，可是跳轉的頁面卻沒有跳轉到input配置的錯誤頁面，而是返回
到了success正確頁面。
嚴重: Content-Type not allowed: filedata "upload__5b01657_11a329d4dcf__8000_00000000.tmp" text/plain
《我的打印輸出DEBUG語句內容:File:null FlieName:null type:null》即攔截類型成功了
java.lang.NullPointerException
at java.io.FileInputStream.<init>(FileInputStream.java:103)
at com.study.web.util.FileUploadUtil.uploadFile(FileUploadUtil.java:36)
at com.study.web.action.UploadFileAction.execute(UploadFileAction.java:58)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)。。。
2008-5-29 10:59:07 com.opensymphony.xwork2.util.logging.commons.CommonsLogger warn
警告: Could not find property [org.apache.catalina.jsp_file]
2008-5-29 10:59:07 com.opensymphony.xwork2.util.logging.commons.CommonsLogger warn
警告: Could not find property [struts]
2008-5-29 10:59:07 com.opensymphony.xwork2.util.logging.commons.CommonsLogger info
信息: Removing file filedata \tmp\upload__5b01657_11a329d4dcf__8000_00000000.tmp
原因及解決辦法：在該文件上傳Action中只配置了FileUploadInterceptor后缺少配置了defaultStack攔截器.
在ACTION中配置玩defaultStack攔截器后改錯誤消失。
9---struts.properties中全局配置文件大小，再使用默認FileUploadInterceptor攔截器時候能實現攔截的功能但是后臺出現異常。
嚴重: Unable to parse request
org.apache.commons.fileupload.FileUploadBase$SizeLimitExceededException: the request was rejected because its size (380) exceeds the configured maximum (10)
at org.apache.commons.fileupload.FileUploadBase$FileItemIteratorImpl.<init>(FileUploadBase.java:914)
原因：未知。將全局配置中的限制大小去掉，再重新在ACTION中覆蓋配置FileUploadInterceptor攔截器設置大小和文件類型限制，可消除異常。
10---多文件上傳中，其中一個傳被限制的文件如限制aplication/msword(即.doc)文件，允許傳文本文件。然而當夾雜在一起傳的時候，后臺能截獲類型錯誤不可傳信息，但是
實際卻還是上傳成功。
嚴重: Content-Type not allowed: filedata "upload_4d958287_11a33e76ab9__8000_00000007.tmp" application/msword
file is :\tmp\upload_4d958287_11a33e76ab9__8000_00000006.tmp fileName:project.txt fileType:text/plain
file is :\tmp\upload_4d958287_11a33e76ab9__8000_00000007.tmp fileName:application base.doc fileType:application/msword
file is :\tmp\upload_4d958287_11a33e76ab9__8000_00000008.tmp fileName:zhongqi-bug.txt fileType:text/plain
原因：忘記了繼承ActionSupport類。繼承后異常消失。
11--文件上傳異常，不能創建File文件
Cannot create type class java.io.File from value C:\Documents and Settings\admin\桌面\OrderReporterServiceImp.java - [unknown location]
原因：忘記了在form表單里將enctype設置成文件上傳格式：enctype="multipart/form-data"
12--當使用限制文件類型和大小的時候拋出空指針異常
java.lang.NullPointerExceptiondemo.struts2.action.ValidatFileUploadAction.execute(ValidatFileUploadAction.java:71)sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)原因：在ACTION中配置了fileUpload攔截器后忘記了配置默認攔截器：defautlStack。注意當ACTION中配置自己的攔截器后需要顯示配置默認
攔截器defaultStack
13--在國際化時候拋空指針異常：
16:31:12,812 ERROR [jsp]:253 - Servlet.service() for servlet jsp threw exception
java.lang.NullPointerException at java.text.MessageFormat.applyPattern(MessageFormat.java:414)
at java.text.MessageFormat.<init>(MessageFormat.java:350)
at com.opensymphony.xwork2.DefaultTextProvider.getText(DefaultTextProvider.java:70)
原因：忘記了在struts.xml中配置國際化常量，或者在struts.properties中配置全局國際化常量 struts.custom.i18n.resources=globeMessage
14-- struts action的配置文件加載失敗：
Unable to load configuration. - result - file:/D:/Java/apache-tomcat-5.5.20/webapps/mysts/WEB-INF/classes/test.xml:10:26
Caused by: No result type specified for result named 'error', perhaps the parent package does not specify the result type? - result - file:/D:/Java/apache-tomcat-5.5.20/webapps/mysts/WEB-INF/classes/test.xml:10:26
at com.opensymphony.xwork2.config.providers.XmlConfigurationProvider.buildResults(XmlConfigurationProvider.java:609)
原因：忘記了繼承包struts-default
15-- struts action 配置文件注意事項：
1. 別忘記了繼承struts-default默認配置包
2.如果配置命名空間，一定要以"/"開始，例如：namespace="/test"
3.每個模塊struts action配置文件中都可以配置全局result，global-result 經測試不會沖突，STRTUS會智能尋找該Action請求的
模塊STRUTS ACTION配置包
關鍵字: 警告: no configuration found for the specified action
警告: No configuration found for the specified action: 'ShowMessage' in namespace: ''. Form action defaulting to 'action' attribute's literal value.
解決方法：
經過測試發現，是沒有正確使用tag的原因，這種情況下，正確的寫法應該是，<s:form name="login" method="post" action="login" >
您是否添加了action這個呢？