需要fileupload.jar与io.jar包共同完成。构建完成路径后可继续。
<form action="UploadServlet" method="post" enctype="multipart/form-data"> 学号:<input type="text"/><br/> 姓名:<input type="text"/><br/> 上传照片:<input type="file"/><br/> <input type="submit" value="注册"/> </form>
注意：
1.文件上传必须要使用post，以避免用get方法时传输总量超过搜索框所能承载最大字符数。
2.必须加入enctype="multipart.form-data"字段
3.文件处需用“file”
三、Servlet部分package webtest; import java.io.File; import java.io.IOException; import java.util.Iterator; import java.util.List; import javax.servlet.ServletException; import javax.servlet.annotation.WebServlet; import javax.servlet.http.HttpServlet; import javax.servlet.http.HttpServletRequest; import javax.servlet.http.HttpServletResponse; import org.apache.commons.fileupload.FileItem; import org.apache.commons.fileupload.FileItemFactory; import org.apache.commons.fileupload.FileUploadBase; import org.apache.commons.fileupload.FileUploadException; import org.apache.commons.fileupload.disk.DiskFileItemFactory; import org.apache.commons.fileupload.servlet.ServletFileUpload; /** * Servlet implementation class UploadServlet */ @WebServlet("/UploadServlet") public class UploadServlet extends HttpServlet { private static final long serialVersionUID = 1L; protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { request.setCharacterEncoding("utf-8");// 请求编码处理，传输时 response.setCharacterEncoding("utf-8");// 响应编码处理,传输时 response.setContentType("utf-8");// 响应编码处理，显示时 boolean isMultipart = ServletFileUpload.isMultipartContent(request);// 判断是否有entype="multipart/form-data"部分 if (isMultipart) { try { FileItemFactory factory = new DiskFileItemFactory(); ServletFileUpload upload = new ServletFileUpload(factory); //设置上传时的内存缓冲区大小，超出时写入临时文件 10kb ((DiskFileItemFactory) factory).setSizeThreshold(10240);//单位byte //设置临时文件目录，防止系统空间不足 ((DiskFileItemFactory) factory).setRepository(new File(request.getSession().getServletContext().getRealPath("Uploadtemp")));//动态获取Uploadtemp文件夹位于该项目中的位置 //控制上传单个文件的最大值 20kb upload.setSizeMax(20480);//单位byte List<FileItem> items = upload.parseRequest(request);// 解析form中的所有请求字段，并保存在item中 Iterator<FileItem> iter = items.iterator(); while (iter.hasNext()) { // 解析时无顺序，因此需根据名字查找 FileItem item = iter.next(); if (item.isFormField()) {//非文件数据 String itemName = item.getFieldName();//获取非文件的范围数据名 if (itemName.equals("sno")) { int sno = -1; sno = Integer.parseInt(item.getString("utf-8")); } else if (itemName.equals("sname")) { String sname = null; sname = item.getString("utf-8"); } else { System.out.println("其他字段..."); } } else {//文件上传 String fileName = item.getName();//获取文件范围数据。路径及其名称 //判断文件类型 String ext = fileName.substring(fileName.indexOf(".")+1); if(!(ext.equals("png")||ext.equals("gif")||ext.equals("jpg"))) { System.out.println("仅支持png.gif,jpg类型文件"); return ; } String path = request.getSession().getServletContext().getRealPath("Upload");//动态获取Upload文件夹位于该项目中的位置 File file = new File(path,fileName); item.write(file);//定义上传路径，多为服务器路径 System.out.println(fileName+"上传成功"); } item.delete();//删除临时目录的文件 } } catch(FileUploadBase.SizeLimitExceededException e) { System.out.println("最大20KB"); } catch (FileUploadException e) { // TODO Auto-generated catch block e.printStackTrace(); } catch (Exception e) { // TODO Auto-generated catch block e.printStackTrace(); } } } /** * @see HttpServlet#doPost(HttpServletRequest request, HttpServletResponse * response) */ protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { // TODO Auto-generated method stub doGet(request, response); } }
注：
1.若该处标红且鼠标悬停后未找到包，则可以使用"alt"+"https://www.jb51.net/"组合键选择下图第一个类来导入。
