1.浏览器端：选择图片、提交表单，同时将图片发送给服务器

<form action=”” method=”post” enctype=”multipart/form-data”><input type=”file” name=”image”><input type=”submit”>上传的内容，都在请求体中。2.服务器端：1）手动获得请求体，需要手动解析。request.getInputStream()2）使用servlet3.03）第三方工具 – apache-commons-fileupload4）struts2

@WebServlet("/FileUploadServlet")@MultipartConfig        //表示支持文件上传，否则获得nullpublic class FileUploadServlet extends HttpServlet {    private static final long serialVersionUID = 1L;protected void doGet(HttpServletRequest request, HttpServletResponse response)         throws ServletException, IOException {    //1 普通字段    String username = request.getParameter("username");    System.out.println(username);    //2 上传字段    Part part = request.getPart("image");    //2.1 获得文件名       // * IE         --> C:\Users\liangtong\Desktop\heima.txt    // * 其他浏览器  --> heima.txt    String contentDisposition = part.getHeader("Content-Disposition");    System.out.println(contentDisposition);    // * 截取文件名    int start = contentDisposition.indexOf("filename=") + 10;    int end = contentDisposition.length() - 1;    String fileName = contentDisposition.substring(start, end);    // * 浏览器兼容  -- lastIndexOf() 如果没有获得返回 -1    fileName = fileName.substring( fileName.lastIndexOf("\\") + 1);    System.out.println(fileName);    //2.2 获得上传文件内容    InputStream is = part.getInputStream();    //2.3 将流写入到服务器文件中    // * 上传目录    String dir = this.getServletContext().getRealPath("/WEB-INF/upload");    File file = new File(dir , fileName);    // * 流的对拷    FileOutputStream out = new FileOutputStream(file);    byte[] buf = new byte[1024];    int len = -1;    while( (len = is.read(buf)) != -1 ){        out.write(buf, 0, len);    }    out.close();    is.close();}protected void doPost(HttpServletRequest request, HttpServletResponse response)         throws ServletException, IOException {    doGet(request, response);}