Extjs上传图片

package cn.com.ajaxbear.action;

import java.io.File;
import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.util.UUID;

import org.apache.struts2.ServletActionContext;

import cn.com.ajaxbear.util.XResponse;

public class UploadAction extends BaseAction {

    private File upload;
    private String uploadContentType;
    public File getUpload() {
        return upload;
    }

    public void setUpload(File upload) {
        this.upload = upload;
    }

    public String getUploadContentType() {
        return uploadContentType;
    }

    public void setUploadContentType(String uploadContentType) {
        this.uploadContentType = uploadContentType;
    }

    public String getUploadFileName() {
        return uploadFileName;
    }

    public void setUploadFileName(String uploadFileName) {
        this.uploadFileName = uploadFileName;
    }

    // 上传文件的文件名
    private String uploadFileName;
    
    private String getFileExp(String name){
        int pos = name.lastIndexOf(".");
        
        return name.substring(pos);
    }

    @Override
    public String execute() throws Exception {
        //首先判断用户是否曾经上传过,如果上传过,则删掉原来的文件(这里我没考虑其他情况,考虑周全还要写一些代码)
        String oldImageName = request.getParameter("oldImageName");
        //如果存在则删除
        if (!"noImage".equalsIgnoreCase(oldImageName)) {
            File oldFile = new File(ServletActionContext
                .getServletContext().getRealPath("/")
                + "UploadImages" + File.separator+oldImageName);
            oldFile.delete();
        }
        System.out.println(oldImageName);
        //为用户新上传的图片新取一个名字
        String newName = UUID.randomUUID().toString();
        //获取用户上传的图片格式
        String exp = getFileExp(uploadFileName);
        //将文件写入文件夹
        FileOutputStream fos = new FileOutputStream(ServletActionContext
                .getServletContext().getRealPath("/")
                + "UploadImages" + File.separator + newName+exp);
        FileInputStream fis = new FileInputStream(upload);
        byte[] buffer = new byte[10240];
        int len = 0;
        int total = fis.available();
        System.out.println("文件大小为:"+total);
        while ((len = fis.read(buffer)) > 0) {
            fos.write(buffer, 0, len);
            fos.flush();
        }
        fis.close();
        fos.close();
        //返回图片名称(路径我是在前台写死了的),注意返回的contentType不能是text/json;
        XResponse.sendMSG(response, "{success : true,msg:'"+newName+exp+"'}","text/html; charset=utf-8");
        return NONE;
    }
}