struts2中文件上传详解
struts2中文件上传的二个限制,一个是struts.multipart.maxSize,如果不设置,struts2 的核心包下的default.properties文件里有默认的大小设置struts.multipart.maxSize=2097152,即2M. 这是struts2文件上传的第一道关.
第二道关是inteceptor中的maximumSize. 当真实的文件大小能通过第一道关时.针对不同的action中配置的inteceptor,maximumSize才能发挥相应的拦截作用.
比如struts.multipart.maxSize=50M. actionA中inteceptorA的maximumSize=30M. actionB中inteceptorB的maximumSize=10M.
struts.multipart.maxSize=50M对于inteceptorA,B都会起到第一关的作用.而inteceptorA和inteceptorB可以在通过第一关之后,根据自己的业务定制各自针对拦截器起作用的maximumSize
如果真实的文件>50M. 抛出会抛出the request was rejected because its size (XXXX) exceeds the configured maximum (XXXX)异常，他是不能被国际化的，因为这个信息是commons-fileupload组件抛出的,是不支持国际化这信息.
struts2.2 org.apache.commons.fileupload.FileUploadBase.java中
/**
* Creates a new instance.
* @param ctx The request context.
* @throws FileUploadException An error occurred while
* parsing the request.
* @throws IOException An I/O error occurred.
*/
FileItemIteratorImpl(RequestContext ctx)
throws FileUploadException, IOException {
if (ctx == null) {
throw new NullPointerException("ctx parameter");
}
String contentType = ctx.getContentType();
if ((null == contentType)
|| (!contentType.toLowerCase().startsWith(MULTIPART))) {
throw new InvalidContentTypeException(
"the request doesn't contain a "
+ MULTIPART_FORM_DATA
+ " or "
+ MULTIPART_MIXED
+ " stream, content type header is "
+ contentType);
}
InputStream input = ctx.getInputStream();
if (sizeMax >= 0) {
int requestSize = ctx.getContentLength();
if (requestSize == -1) {
input = new LimitedInputStream(input, sizeMax) {
protected void raiseError(long pSizeMax, long pCount)
throws IOException {
FileUploadException ex =
new SizeLimitExceededException(
"the request was rejected because"
+ " its size (" + pCount
+ ") exceeds the configured maximum"
+ " (" + pSizeMax + ")",
pCount, pSizeMax);
throw new FileUploadIOException(ex);
}
};
} else {
///问题就在这里////////////////////////////////////
if (sizeMax >= 0 && requestSize > sizeMax) {
throw new SizeLimitExceededException(
"the request was rejected because its size ("
+ requestSize
+ ") exceeds the configured maximum ("
+ sizeMax + ")",
requestSize, sizeMax);
}
}
}
String charEncoding = headerEncoding;
if (charEncoding == null) {
charEncoding = ctx.getCharacterEncoding();
}
boundary = getBoundary(contentType);
if (boundary == null) {
throw new FileUploadException(
"the request was rejected because "
+ "no multipart boundary was found");
}
notifier = new MultipartStream.ProgressNotifier(listener,
ctx.getContentLength());
multi = new MultipartStream(input, boundary, notifier);
multi.setHeaderEncoding(charEncoding);
skipPreamble = true;
findNextItem();
如果InteceptorA上传的是40M的真实文件.那么此时拦截器InteceptorA会访问国际化信息:struts.messages.error.file.too.larges对应的值.
当且仅当上传文件<=30M的时候,InteceptorA才会成功上传.
下面是解决struts.multipart.maxSize提示信息不友好的问题.
当超过50M时.commons-fileupload抛出运行时异常,struts2会把这个异常看到是action级别的异常.所以会将异常信息
the request was rejected because its size (XXXX) exceeds the configured maximum (XXXX)写到actionError里面.我们需要做的就是在action里覆盖addActionError方法
@Override
public void addActionError(String anErrorMessage) {
//改从国际化里取值
if (anErrorMessage
.startsWith("the request was rejected because its size")) {
super.addActionError(getText("struts.multipart.maxSize.limit"));
} else {
super.addActionError(anErrorMessage);
}
}
相应的配置文件
struts.multipart.maxSize.limit=系统上传的文件最大为50M
struts.messages.error.file.too.larges=新广告批量上传的文件最大为5M
struts.messages.error.content.type.not.allowed=上传的文件格式目前仅支持xls格式
struts.messages.error.uploading=上传文件失败
struts.messages.invalid.token=您已经提交了表单，请不要重复提交。
fileupload.filenums.exceed=已经有超过5个文件在运行,请稍候再试
filedownload.rows.exceed=由于您选择的广告组内广告数量太多，请分组下载
accountNotExist=客户不存在
invalidTask=无效的任务
注意,由于inteceptor中途返回,原来页面上输入的其他文本内容也都不见了，也就是说params注入失败。
这个是没办法的，因为这个异常是在文件上传之前捕获的，文件未上传，同时params也为注入，所以这时最好重定向到一个jsp教程文件，提示上传失败，然后重写填写相应信息。
解决办法:最好跳到一个专门显示错误的页.而不要返回操作页.
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注意,拦截器所谓的同名配置覆盖,是重复执行的,比如defaultStack中是包含fileUpload,token的. 如果将<interceptor-ref name="defaultStack" />放到显示定义的拦截器之后,会覆盖显示定义的拦截器.
下面是正确的拦截器顺序:
<action name="BatchMIADOperation!*" method="{1}"
class="com.*****.***.action.multiidea.batchad.BatchMIADOperationAction">
<interceptor-ref name="defaultStack" />
<interceptor-ref name="fileUpload">
<param name="maximumSize">5242880</param>
<!--
<param name="allowedTypes">
application/vnd.ms-excel
</param>
-->
</interceptor-ref>
<interceptor-ref name="token">
<param name="excludeMethods">
init,search,updateBatchCpcMatch,batchExportMIAD,downloadWhenError
</param>
</interceptor-ref>
<result name="input">
/WEB-INF/jsp/multiidea/batchad/BatchMIAD.jsp
</result>
<result name="success">
/WEB-INF/jsp/multiidea/batchad/BatchMIAD.jsp
</result>
<result name="invalid.token">
/WEB-INF/jsp/multiidea/batchad/BatchMIAD.jsp
</result>
</action>
补充：Jsp教程,Java技巧及代码 
