Struts2文件上传（二）-文件上传拦截器

看官方文档学习了一下，稍微记录一下。

File Upload Interceptor

1.该拦截器有三个可选参数

• maximumSize：文件的最大字节数，默认是2M。注意，它和 struts.multipart.maxSize 是有区别的

文档上的描述：

There are two separate file size limits. First is struts.multipart.maxSize which comes from the Struts 2 default.properties file. This setting exists for security reasons to prohibit a malicious user from uploading extremely large files to file up your servers disk space. This setting defaults to approximately 2 megabytes and should be adjusted to the maximum size file (2 gigs max) that your will need the framework to receive. If you are uploading more than one file on a form the struts.multipart.maxSize applies to the combined total, not the individual file sizes. The other setting, maximumSize, is an interceptor setting that is used to ensure a particular Action does not receive a file that is too large. 

• allowedTypes：允许上传的文件类型，如 text/html ，text/plain

• allowedExtensions：允许上传的文件的后缀，如 .html

如果文件不符合设置，会产生相应的错误。

2.错误类型

• struts.messages.error.uploading - a general error that occurs when the file could not be uploaded
• struts.messages.error.file.too.large - occurs when the uploaded file is too large
• struts.messages.error.content.type.not.allowed - occurs when the uploaded file does not match the expectedcontent types specified
• struts.messages.error.file.extension.not.allowed - occurs when the uploaded file does not match the expectedfile extensions specified

这样我们就可以在页面上显示相应的错误信息。我们可以再配置文件中重写这些错误信息，显得更友好。

3.配置文件

<action name="upload" class="org.ygy.action.DocumentAction" method="upload">    <interceptor-ref name="fileUpload">    <param name="allowedTypes">image/jpeg</param>    <param name="maximumSize">10240</param>    </interceptor-ref>    <interceptor-ref name="defaultStack" />        <result name="input">/upload.jsp</result>//出错后，返回界面    <result name="success">/upload_success.jsp</result>    </action>