Uploadify是JQuery的一个上传插件，实现的效果非常不错，带进度显示。而且是Ajax的，省去了自己写Ajax上传功能的麻烦。不过官方提供的实例时php版本的，本文将详细介绍Uploadify在J2EE中的使用。

1.引入头文件（注意一定要把jQuery放在前面）：

注意：uploader是上传的Action路径名；formData是传递给Action的参数列表。

<script src="lib/jquery-1.8.3.min.js"></script>
<script src="lib/uploadify/jquery.uploadify.min.js" type="text/javascript"></script>
<script type="text/javascript">$(function() {$('#projectfile').uploadify({'swf'      : 'lib/uploadify/uploadify.swf','uploader' : 'ProjectfileAdd.action','formData': {'projectid': '${project.id}'},'fileObjName' : 'file','fileSizeLimit' : '0','onQueueComplete' : function(queueData) {alert(queueData.uploadsSuccessful + ' files were successfully uploaded.');}});});
</script>

2.需要上传的地方添加一个<form>，里面有一个<input>（注意其id属性）：

<form><input id="projectfile" name="file" type="file" ></input>
</form>

3.看一下<input>效果如下，还挺美观的

4.后台的Action就是一个普通的上传文件的Action，示例如下：

package dc.action.projectfile;import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.sql.Timestamp;
import java.util.Date;
import java.util.Map;import org.apache.struts2.ServletActionContext;import com.opensymphony.xwork2.ActionContext;
import com.opensymphony.xwork2.ActionSupport;import dc.bean.Project;
import dc.bean.Projectfile;
import dc.bean.User;
import dc.service.ProjectService;
import dc.service.ProjectfileService;public class ProjectfileAdd extends ActionSupport {private static final int FILE_SIZE=16*1024;private int projectid;private ProjectService projectService;private ProjectfileService projectfileService;private File file;private String fileFileName;private String fileContentType;public int getProjectid() {return projectid;}public void setProjectid(int projectid) {this.projectid = projectid;}public ProjectService getProjectService() {return projectService;}public void setProjectService(ProjectService projectService) {this.projectService = projectService;}public ProjectfileService getProjectfileService() {return projectfileService;}public void setProjectfileService(ProjectfileService projectfileService) {this.projectfileService = projectfileService;}public File getFile() {return file;}public void setFile(File file) {this.file = file;}public String getFileFileName() {return fileFileName;}public void setFileFileName(String fileFileName) {this.fileFileName = fileFileName;}public String getFileContentType() {return fileContentType;}public void setFileContentType(String fileContentType) {this.fileContentType = fileContentType;}public static int getFileSize() {return FILE_SIZE;}//写入文件时候用到的函数public void upLoadFile(File source,File target){InputStream in=null;OutputStream out=null;try{in=new BufferedInputStream(new FileInputStream(source),FILE_SIZE);out=new BufferedOutputStream(new FileOutputStream(target),FILE_SIZE);//in-->image-->outbyte[] image=new byte[FILE_SIZE];while(in.read(image)>0){out.write(image);}}catch(IOException ex){ex.printStackTrace();}finally{try{in.close();out.close();}catch(IOException ex){ex.printStackTrace();}}}public String execute() {try {Projectfile projectfile=new Projectfile();projectfile.setName(fileFileName);Project project=projectService.ReadByID(projectid);projectfile.setProject(project);projectfile.setModifytime( new Timestamp(new Date().getTime()));String filepath="file/"+project.getId()+"/"+fileFileName;projectfile.setFilepath(filepath);projectfile.setFilesize(file.length());//不是连接到外网的文件projectfile.setFilelink(0);projectfile.setContenttype(fileContentType);//--记录编辑人------------------ActionContext context = ActionContext.getContext();Map sessionMap = context.getSession();User currentuser=(User)sessionMap.get("user");projectfile.setUser(currentuser);//------------------------------//projectfile.setFilesize(1);projectfileService.save(projectfile);//文件上传，存至硬盘//ServletActionContext.getServletContext().getRealPath获得webRoot绝对路径String realfilePath=ServletActionContext.getServletContext().getRealPath("file")+"/"+project.getId()+"/"+this.fileFileName;File targetFile=new File(realfilePath);targetFile.getParentFile().mkdirs();upLoadFile(file,targetFile);} catch (Exception ex) {ex.printStackTrace();return ERROR;}return SUCCESS;}
}

Uploadify官方网站：http://www.uploadify.com/

Uploadify下载：http://download.csdn.net/detail/leixiaohua1020/6376463