上传和下载

String filename="E://5656.txt";
//设置文件MIME类型
response.setContentType(getServletContext().getMimeType(filename));
//设置Content-Disposition
response.setHeader("Content-Disposition", "attachment;filename="+filename);
InputStream is = new FileInputStream(filename);
ServletOutputStream out =response.getOutputStream();
int len = -1 ;
byte b[]= new byte[1024];
while((len=is.read(b))!=-1){
out.write(b, 0, len);

/*
* 上传三步 1 得到工厂
* 2通过工厂创建解析器
* 3解析request 得到FileItem集合
* 4.遍历FileItem集合，
*/
DiskFileItemFactory factory = new DiskFileItemFactory() ;
ServletFileUpload sfu = new ServletFileUpload(factory);
try {
List fileItemList = sfu.parseRequest(request);
FileItem fi1 = fileItemList.get(0);//获得用户名
FileItem fi2 =fileItemList.get(1);//获得文件
//现在是普通文本的操作
System.out.println("表单项名字"+fi1.getFieldName()+"值为"+fi1.getString("utf-8"));
//现在开始处理文件
//这里需要注意有的浏览器上传的文件名是绝对路径 这里需要切割
String filename = fi2.getName(); //e://3.jpg
int index = filename.lastIndexOf("\\");
//如果Index的值为-1则说明正常
if(index!=-1){
filename =filename.substring(index+1);
}
//现在输出filename看看
System.out.println(filename); //获得 文件名.后缀
//路径
String path =request.getServletContext().getRealPath("/pic");
System.out.println(path);
//创建文件
File file = new File(path+"//new.txt");
fi2.write(file);

} catch (Exception e) {

e.printStackTrace();
}