struts2默认文件上传大小为2M,如需修改默认大小,解决方法如下：

<struts>

      <constant name="struts.multipart.maxSize" value="20971520" /> <!-- 设置允许最大值  20MB(1024*1024*20) -->

      <package name="build" extends="struts-default">

	    <action name="fileUpload" class="com.home.UploadAction" method="upload">

		   <result name="success">/success.jsp</result>

		   <result name="input">/error.jsp</result>

		   <!-- <param name="allowedTypes"></param> 允许文件类型 -->

		   <interceptor-ref name="fileUpload">

			   <param name="maximumSize">5242880</param>

		   </interceptor-ref>

		   <interceptor-ref name="defaultStack" /> <!-- 默认拦截器 -->

	    </action>

      </package>

</struts>

struts.multipart.maxSize和fileUpload拦截器的maximumSize属性分工不同

1、struts.multipart.maxSize控制整个项目所上传文件的最大size。超过这个值,后台报错

the request was rejected because its size (51224434) exceeds the configured maximum (20971520)

2、fileUpload拦截器的maximumSize属性必须小于struts.multipart.maxSize的值。

struts.multipart.maxSize默认2M,当maximumSize大于2M时,必须设置struts.multipart.maxSize的值大于maximumSize。

3、当上传的文件在maxSize和maximumSize之间时,系统提示

The file is to large to be uploaded: file "apache-tomcat-7.0.47.zip""upload_94d9d06c_a45f_b91e4c915c02_00000002.tmp" 8782342

4、当上传文件小于maximumSize时,上传成功。

总结：所上传文件大小应 < maximumSize < maxSize