文件上传

浏览器端的要求
- 表单的提交方法必须是post
- 必须有一个文件上传组件
- 必须设置表单的enctype="multipart/form-data


       用户名:
 
       文件:

服务器端的要求
- 在Servelt上添加注解

@MultipartConfig
@WebServlet("/upload3")
@MultipartConfig
public class upload3 extends HttpServlet {
    private static final long serialVersionUID = 1L;
       
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

文件上传如何获取数据

获取普通上传组件
request.getParameter(name属性的值);
获取文件上传组件
Part part = request.getPart("表单文件组件的name名");

//获取文件真实文件名
String header = part.getHeader("content-disposition");
String realName=header.substring(header.indexOf("filename=")+10,header.length()-1);

//获取文件的大小
long size = part.getSize();

//把文件写到指定路径
part.write("d:/"+realName);

<%@ page contentType="text/html;charset=UTF-8" language="java" %>

  
    $Title$
    

    
  
  
  
    
    
      
      UPLOAD555

@WebServlet(name = "UploadServlet",urlPatterns = "/upload.action")
@MultipartConfig
public class UploadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        request.setCharacterEncoding("utf-8");

        Part part = request.getPart("upload");
        String filename = part.getSubmittedFileName();
        UUID uuid = UUID.randomUUID();

        String strPath = request.getServletContext().getRealPath("") + "upload" + File.separator;
        File file = new File(strPath);
        if (!file.exists()){
            file.mkdirs();
        }

        part.write(strPath  + uuid + filename);
        request.getSession().setAttribute("picpath",uuid+filename);
        response.setContentType("text/html;charset:utf-8");
        response.getWriter().println(uuid + filename);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

文件上传可能会遇到的问题

名字重复的问题如果用户提交了两个1.png只会保存第一次这样在实际开发中是很不可取的解决方法uuid

编写上传页面

index.jsp

<%@ page contentType="text/html;charset=UTF-8" language="java" %>


  
  Insert title here



  name:
  选择文件：

开发处理文件上传的Servlet

1、使用注解@MultipartConfig将一个Servlet标识为支持文件上传。

2、Servlet3.0将multipart/form-data的POST请求封装成Part，通过Part对上传的文件进行操作。

3.使用getSubmittedFileName方法需要tomcat8支持。
　　UploadServlet 代码如下：

  @WebServlet(name = "UploadServlet",urlPatterns = "/upload.do")
@MultipartConfig
public class UploadServlet extends HttpServlet {
    protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        // TODO Auto-generated method stub
        request.setCharacterEncoding("utf-8");

        String strUser = request.getParameter("user");
        System.out.println(strUser);
        response.setContentType("text/html;charset=UTF-8");
        PrintWriter out = response.getWriter();
        request.setCharacterEncoding("UTF-8");
        Part part = request.getPart("pic");
        out.print("文件类型为：" + part.getContentType() + "
");
        out.print("文件的大小为：" + part.getSize() + "
");
        out.print("文件信息为：" + part.getHeader("content-disposition") + "
");
        out.print("文件的名字为：" + part.getSubmittedFileName());

        //得到服务器项目发布运行所在地址
        String strFolder = request.getServletContext().getRealPath("/image")+ File.separator;
        File folder = new File(strFolder);
        if(!folder.exists())
        {
            folder.mkdir();
        }
        //  此处未使用UUID来生成唯一标识,用日期做为标识
        String strNewFilePath = new SimpleDateFormat("yyyyMMddHHmmss").format(new Date())+ part.getSubmittedFileName();
        String strFinalPath = strFolder + strNewFilePath;
        //查看文件上传路径,方便查找
        System.out.println(strFinalPath);
        part.write(strFinalPath);
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {

    }
}

ajax上传

<%--
  Created by IntelliJ IDEA.
  User: ttc
  Date: 2018/7/13
  Time: 8:47
  To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>

  
    $Title$