java web 文件上传

2019-10-16 08:17:10来源：博客园阅读 ()

java web 文件上传

文件资源位置:web/img下
HTML页面

<!DOCTYPE html>

<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>学习文件下载</title>
</head>
<body>
    <h1>使用超链接</h1>
    <a href="/filedown/img/abc.png">图片1</a>
    <a href="/filedown/img/aa.flv">视频1</a>
    <a href="/filedown/img/奥尼尔.gif">图片2</a>
<hr/>
    <a href="/filedown/downServlet?filename=abc.png">图片1</a>
    <a href="/filedown/downServlet?filename=aa.flv">视频1</a>
    <a href="/filedown/downServlet?filename=奥尼尔.gif">中文图片2</a>
</body>
</html>

Servlet 类
@WebServlet("/downServlet")
public class FileDownServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
　　　　　//获取请求参数，文件名称
        String filename = request.getParameter("filename");
        ServletContext context = this.getServletContext();
        //找到服务器文件的真实路径
        String realPath = context.getRealPath("/img/" + filename);
        //使用字节流关联
        FileInputStream fis=new FileInputStream(realPath);
        /* 设置响应头
            响应头类型：content-type
            响应头打开方式：content-disposition
         */
        String mimeType = context.getMimeType(filename);
        response.setHeader("content-type",mimeType);
　　　　　　//获取user-agent请求头
        String agent = request.getHeader("user-agent");
　　　　　　//使用工具类方法编码文件名即可
        filename = DownLoadUtils.getFileName(agent, filename);

        response.setHeader("content-disposition","attachment;filename="+filename);
　　　　　　//将输入流的数据写出到输出流中
        ServletOutputStream sos = response.getOutputStream();
        byte[] bytes=new byte[1024*8];
        int len=0;
        while ((len=fis.read(bytes))!=-1){
            sos.write(bytes,0,len);
        }
        fis.close();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        this.doPost(request,response);
    }
}

util工具类：对文件名编码

public class DownLoadUtils {

    public static String getFileName(String agent, String filename) throws UnsupportedEncodingException {
        if (agent.contains("MSIE")) {
            // IE浏览器
            filename = URLEncoder.encode(filename, "utf-8");
            filename = filename.replace("+", " ");
        } else if (agent.contains("Firefox")) {
            // 火狐浏览器
            BASE64Encoder base64Encoder = new BASE64Encoder();
            filename = "=?utf-8?B?" + base64Encoder.encode(filename.getBytes("utf-8")) + "?=";
        } else {
            // 其它浏览器
            filename = URLEncoder.encode(filename, "utf-8");
        }
        return filename;
    }
}