jsp 如何实现文件上传和下载功能？

上传：

MyjspForm mf = (MyjspForm) form// TODO Auto-generated method stub

FormFile fname=mf.getFname()

byte [] fn = fname.getFileData()

OutputStream out = new FileOutputStream("D:\\"+fname.getFileName())

Date date = new Date()

String title = fname.getFileName()

String url = "d:\\"+fname.getFileName()

Upload ul = new Upload()

ul.setDate(date)

ul.setTitle(title)

ul.setUrl(url)

UploadDAO uld = new UploadDAO()

uld.save(ul)

out.write(fn)

out.close()

下载：

DownloadForm downloadForm = (DownloadForm)form

String fname = request.getParameter("furl")

FileInputStream fi = new FileInputStream(fname)

byte[] bt = new byte[fi.available()]

fi.read(bt)

//设置文件是下载还是打开以及打开的方式msdownload表示下载；设置字湖集，//主要是解决文件中的中文信息

response.setContentType("application/msdownloadcharset=gbk")

//文件下载后的默认保存名及打开方式

String contentDisposition = "attachmentfilename=" + "java.txt"

response.setHeader("Content-Disposition",contentDisposition)

//设置下载长度

response.setContentLength(bt.length)

ServletOutputStream sos = response.getOutputStream()

sos.write(bt)

return null

jsp页面下载文档是在jsp中有一个a标签 ，当用户点击a标签的时候下载文件。

一般采用href属性直接指向一个服务器地址，只要链接的文件存在,就会给出d出保存对话框.

点击a标签 先执行onclick事件，再请求href中指向的地址。

前端jsp：

<a href="#" onclick="javascript:downloadtest('${app.id}')" id="pluginurl" style="color: #83AFE2text-decoration:underline"></a>

然后在js中：

function downloadtest(id){

var url = "<%=request.getContextPath()%>/app/download" + "/" + id

$("#pluginurl").attr("href",url)

}

后台处理下载逻辑的java代码：

/**

* 下载文件

* @param id appid

* @param response

*/

@RequestMapping(value="/download/{id}")

public void download(@PathVariable String id, HttpServletResponse response){

String filepath = ""

Result result = appService.getAppById(id)

App app = (App) result.getMap().get("app")

if(app == null){

return

}

filepath = app.getUrl()

File file = new File(filepath)

InputStream inputStream = null

OutputStream outputStream = null

byte[] b= new byte[1024]

int len = 0

try {

inputStream = new FileInputStream(file)

outputStream = response.getOutputStream()

response.setContentType("application/force-download")

String filename = file.getName()

filename = filename.substring(36, filename.length())

response.addHeader("Content-Disposition","attachmentfilename=" + URLEncoder.encode(filename, "UTF-8"))

response.setContentLength( (int) file.length( ) )

while((len = inputStream.read(b)) != -1){

outputStream.write(b, 0, len)

}

} catch (Exception e) {

e.printStackTrace()

}finally{

if(inputStream != null){

try {

inputStream.close()

inputStream = null

} catch (IOException e) {

e.printStackTrace()

}

}

if(outputStream != null){

try {

outputStream.close()

outputStream = null

} catch (IOException e) {

e.printStackTrace()

}

}

}

}

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