【Java】Servlet文件上传-无需导入其他Jar包

    <form method="post" action="upload" enctype="multipart/form-data">
        选择文件：<input type="file" id="file" name="file"><br>
        <input type="submit" value="提交">
    </form>

// Servlet3.0 相当于配置web.xml
@WebServlet(name="Upload",urlPatterns={"/upload"})
// 文件上传的注解
@MultipartConfig
public class Upload extends HttpServlet {
    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
            // 解决中文乱码
            response.setContentType("text/html;charset=utf-8");
            request.setCharacterEncoding("utf-8");
            PrintWriter out = response.getWriter();
            File path = new File("D://tmp");
            if (!path.exists()){
                path.mkdir();
            }
            Part part = request.getPart("file");
            out.println("size:"+part.getSize()+"<br>");
            // tomcat7 下需要下面的方法获取文件名
            String cd = part.getHeader("Content-Disposition");
            //截取不同类型的文件需要自行判断
            String filename = cd.substring(cd.lastIndexOf("=")+2, cd.length()-1);
            // Tomcat8以上只需要 part.getSubmittedFileName() 方法可以直接获取
//            将文件上传到服务器
            String filePath = path.getPath() + File.separator + filename;
            part.write(filePath);
            System.out.println("File Upload : " + filePath);
    }

}