Struts2 上传文件
package action;import java.io.*;import com.opensymphony.xwork2.ActionSupport;public class UploadAction extends ActionSupport { private File upload; private String fileName; private String uploadContentType; public String getUploadFileName() { return fileName; } public void setUploadFileName(String fileName) { this.fileName = fileName; } public File getUpload() { return upload; } public void setUpload(File upload) { this.upload = upload; } public void setUploadContentType(String contentType) { this.uploadContentType=contentType; } public String getUploadContentType() { return this.uploadContentType; } public String execute() throws Exception { java.io.InputStream is = new java.io.FileInputStream(upload); java.io.OutputStream os = new java.io.FileOutputStream("d:\\upload\" + fileName); byte buffer[] = new byte[8192]; int count = 0; while((count = is.read(buffer)) > 0) { os.write(buffer, 0, count); } os.close(); is.close(); return SUCCESS; }} 在execute方法中的实现代码就很简单了，只是从临时文件复制到指定的路径（在这里是d:\upload）中。上传文件的临时目录的默认值是javax.servlet.context.tempdir的值，但可以通过struts.properties（和struts.xml在同一个目录下）的struts.multipart.saveDir属性设置。Struts2上传文件的默认大小限制是2M（2097152字节），也可以通过struts.properties文件中的struts.multipart.maxSize修改，如struts.multipart.maxSize=2048 表示一次上传文件的总大小不能超过2K字节。
下面的代码是上传文件的JSP页面代码：
<%@ page language="java" import="java.util.*" pageEncoding="GBK"%><%@ taglib prefix="s" uri="/struts-tags"%><html> <head> <title>上传单个文件</title> </head> <body> <s:form action="upload" namespace="/test" enctype="multipart/form-data"> <s:file name="upload" label="输入要上传的文件名" /> <s:submit value="上传" /> </s:form> </body></html>也可以在success.jsp页中通过<s:property>获得文件的属性（文件名和文件内容类型），代码如下：
<html> <head> <script language="javascript">function addComponent(){ var uploadHTML = document.createElement( "<input type='file' name='upload'/>"); document.getElementById("files").appendChild(uploadHTML); uploadHTML = document.createElement( "<p/>"); document.getElementById("files").appendChild(uploadHTML);}</script> </head> <body> <input type="button" onclick="addComponent();" value="添加文件" /> <br /> <form onsubmit="return true;" action="/struts2/test/upload.action" method="post" enctype="multipart/form-data"> <span id="files"> <input type='file' name='upload' /> <p /> </span> <input type="submit" value="上传" /> </form> </body></html>上面的javascript代码可以生成任意多个<input type=’file’>标签，name的值都为file（要注意的是，上面的javascript代码只适合于IE浏览器，firefox等其他浏览器需要使用他的代码）。至于Action类，和上传单个文件的Action类基本一至，只需要将三个属性的类型改为List即可。代码如下：package action;import java.io.*;import com.opensymphony.xwork2.ActionSupport;public class UploadMoreAction extends ActionSupport{ private java.util.List<File> uploads; private java.util.List<String> fileNames; private java.util.List<String> uploadContentTypes; public java.util.List<String> getUploadFileName() { return fileNames; } public void setUploadFileName(java.util.List<String> fileNames) { this.fileNames = fileNames; } public java.util.List<File> getUpload() { return uploads; } public void setUpload(java.util.List<File> uploads) { this.uploads = uploads; } public void setUploadContentType(java.util.List<String> contentTypes) { this.uploadContentTypes = contentTypes; } public java.util.List<String> getUploadContentType() { return this.uploadContentTypes; } public String execute() throws Exception { if (uploads != null) { int i = 0; for (; i < uploads.size(); i++) { java.io.InputStream is = new java.io.FileInputStream(uploads.get(i)); java.io.OutputStream os = new java.io.FileOutputStream( "d:\\upload\" + fileNames.get(i)); byte buffer[] = new byte[8192]; int count = 0; while ((count = is.read(buffer)) > 0) { os.write(buffer, 0, count); } os.close(); is.close(); } } return SUCCESS; }} 在execute方法中，只是对List对象进行枚举，在循环中的代码和上传单个文件时的代码基本相同。如果读者使用过struts1.x的上传组件，是不是感觉Struts2的上传功能更容易实现呢？在Struts1.x中上传多个文件时，可是需要建立带索引的属性的。而在Struts2中，就是这么简单就搞定了。