完整代码下载：

http://download.csdn.net/detail/lc448986375/4575723

upload.js:

Ext.onReady(
		function(){
			var form = Ext.create(
					'Ext.form.Panel',
					{
						frame:true,
						title:'文件上传实例',
						width:300,
						height:100,
						renderTo:'upload',
						items:[
						       {
						    	   xtype:'filefield',
						    	   //与后台定义的File属性名必须相同
						    	   name:'file',
						    	   fieldLabel:'上传',
						    	   allowbBlank:false,
						    	   msgTarget:'side',
						    	   buttonText:'选择文件'
						       }
						],
						buttons:[
						        {
						        	text:'上传',
						        	handler:function(){
						        		var form = this.up('form').getForm();
						        		if(form.isValid()){
						        			form.submit(
						        					{
						        						url:'user_upload',
						        						waitMsg:'正在上传',
						        						success:function(fp,o){
						        							Ext.Msg.show(
						        									{
						        										title:'提示信息',
						        										msg:'文件上传成功，上传文件名为：'+o.result.fileFileName,
						        										buttons:Ext.Msg.OK
						        									}
						        							)
						        						}
						        					}
						        			)
						        		}
						        	}
						        }
						]
					}
			)
		}
)

package action;

import java.io.File;

import com.opensymphony.xwork2.ActionSupport;

public class UserAction extends ActionSupport {
	//格式必须为"文件名"+FileName
	private String fileFileName;
	//必须与前台的name相同才可以接收到
	private File file;
	private boolean success;
	
	public String upload(){
		//对文件进行操作，这里只是输出一下文件名
		System.out.println(fileFileName);
		success = true;
		return SUCCESS;
	}
	
	public String getFileFileName() {
		return fileFileName;
	}
	public void setFileFileName(String fileFileName) {
		this.fileFileName = fileFileName;
	}
	public File getFile() {
		return file;
	}
	public void setFile(File file) {
		this.file = file;
	}
	public boolean isSuccess() {
		return success;
	}
	public void setSuccess(boolean success) {
		this.success = success;
	}
}