文件上传下载

最新推荐文章于 2022-09-04 18:39:58 发布

原创最新推荐文章于 2022-09-04 18:39:58 发布 · 149 阅读

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需求准备：commons-fileupload，commons-io两个jar包
对于视图层：注意：form表单的method=“post” enctype=“multipart/form-data”

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<%
String path = request.getContextPath();
String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
%>

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
  <head>
    <base href="<%=basePath%>">
    
    <title>My JSP 'add.jsp' starting page</title>
    
	<meta http-equiv="pragma" content="no-cache">
	<meta http-equiv="cache-control" content="no-cache">
	<meta http-equiv="expires" content="0">    
	<meta http-equiv="keywords" content="keyword1,keyword2,keyword3">
	<meta http-equiv="description" content="This is my page">
	<!--
	<link rel="stylesheet" type="text/css" href="styles.css">
	-->

  </head>
  
  <body>
  
   ${requestScope.mess }
     <form action="servlet/AddServlet" method="post" enctype="multipart/form-data" >   		
    	用户名:<input type="text" name="name"><br>
    	年龄:<input type="text" name="age"><br>
    	分数:<input type="text" name="score"><br>
    	照片:<input type="file" name="photo"><br>      
    	<input type="submit" value="提交">	
    </form>
    
  </body>
</html>

控制层：
FileItem类的主要方法
isFormField():是否是file表单项，是file false，不是file true
getFieldName():表单项name的属性值
getString():对于非file表单项，value的属性值，对于file表单项，文件内容
getName():对于file表单项，是上传文件的名称，对于非file表单项，返回null
getContentType()：对于file表单项，是指文件上传类型，非file表单项，返回null
getSize():对于file表单项，是指文件大小，非file表单项，是指name的长度

package com.bjsxt.servlet;

import java.io.File;
import java.io.IOException;
import java.util.List;
import java.util.UUID;

import javax.servlet.ServletException;
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.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;

import com.bjsxt.entity.Student;
import com.bjsxt.service.StudentService;
import com.bjsxt.service.impl.StudentServiceImpl;

public class AddServlet extends HttpServlet {


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

	
	public void doPost(HttpServletRequest request, HttpServletResponse response)
			throws ServletException, IOException {
		
		//创建FileItemFactory对象
		FileItemFactory factory=new DiskFileItemFactory();
		//ServletFileUpload对象
		ServletFileUpload sfu=new ServletFileUpload(factory);
		sfu.setHeaderEncoding("utf-8");
		//设置文件的大小
		sfu.setFileSizeMax(40*1024);//设置单个文件大小
		sfu.setSizeMax(10*16*1024);//设置多个文件大小
		//通过ServletFileUpload对象实现上传操作，将客户端一个个表单项封装到一个个FileItem中
		List<FileItem> itemList=null;
		try {
			itemList= sfu.parseRequest(request);
		} catch (FileUploadException e) {
			e.printStackTrace();
			request.setAttribute("mess", "只能上传小于16kb的文件");
			request.getRequestDispatcher("/add.jsp").forward(request, response);
			return;
		}
	//遍历
		String name=null;
		int age=0;
		double score=0;
		String realName=null;
		String photoName=null;
		String photoType=null;
		for (int i = 0; i < itemList.size(); i++) {
			FileItem item = itemList.get(i);
			String fieldName = item.getFieldName();
			//普通表单项
			
			if (item.isFormField()) {
				//
				if ("name".equals(fieldName)) {
					name=item.getString("utf-8");
				}
				if ("age".equals(fieldName)) {
					age=Integer.parseInt(item.getString());			
				}
				if ("score".equals(fieldName)) {
					score=Double.parseDouble(item.getString());
				}
			} else {
				//文件表单项
				if ("photo".equals(fieldName)) {
					String contentType = item.getContentType();//images/jpg
					photoType=item.getContentType();
					if(!"image/jpeg".equals(contentType) && !"image/gif".equals(contentType)){
						request.setAttribute("mess", "只能上传jpg和gif文件");
						request.getRequestDispatcher("/add.jsp").forward(request, response);
						return;
					}
					//创建文件上传路径(物理路径)
					/*File dir=new File("C:\\apache-tomcat-7.0.69-windows-x64\\apache-tomcat-7.0.69\\webapps\\updownload1");*/
					//由逻辑路径获得物理路径
					String realPath = this.getServletContext().getRealPath("/upload");
					File dir=new File(realPath);
					
					//判断文件夹是否存在
					if (!dir.exists()) {
						dir.mkdir();
					}
					//指定上传的文件名
					realName = item.getName();
					String type = realName.substring(realName.lastIndexOf("."));
					UUID uuid= UUID.randomUUID();
					photoName=uuid.toString()+type;
					//指定上传的文件夹和文件名
					File file=new File(dir, photoName);
					//上传文件到该位置
					try {
						item.write(file);
					} catch (Exception e) {
						// TODO Auto-generated catch block
						e.printStackTrace();
					}

				 }
				}
				
		}
		Student stu=new Student(name, age, score, realName, photoName, photoType);
		StudentService stuService=new StudentServiceImpl();
		int n=stuService.save(stu);
		    //页面跳转
		    if(n!=0){
		    	//重定向:/后面要跟上下文路径  /stumgr   /stumgr2
		    	response.sendRedirect(request.getContextPath()+"/servlet/ShowAllServlet");
		    }else{
		    	request.setAttribute("mess", "添加失败!");
		    	request.getRequestDispatcher("/add.jsp").forward(request, response);
		    }
	
	}

}

文件下载：
控制层：

package com.bjsxt.servlet;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.net.URLEncoder;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import org.apache.commons.io.IOUtils;

import com.bjsxt.entity.Student;
import com.bjsxt.service.StudentService;
import com.bjsxt.service.impl.StudentServiceImpl;

public class DownloadServlet extends HttpServlet {
	@Override
	protected void service(HttpServletRequest req, HttpServletResponse rep)
			throws ServletException, IOException {
		//接收信息
		int id=Integer.parseInt(req.getParameter("idd"));
		//创建服务层
		StudentService stuService = new StudentServiceImpl();
		Student stu=stuService.findById(id);
		//进行读取下载操作
		//创建输入流和输出流
		String pathname=this.getServletContext().getRealPath("/upload")+"/"+stu.getPhotoName();
		File file=new File(pathname);
		rep.setContentLength((int)file.length());
		rep.setContentType(stu.getPhotoType());
		String header = req.getHeader("User-Agent").toLowerCase();
		String realName = stu.getRealName();
		if (header.indexOf("msie")>=0) {
			realName=URLEncoder.encode(realName,"utf-8");
		} else {
			realName=new String(realName.getBytes("utf-8"),"iso-8859-1");
		}
		rep.setHeader("Content-disposition","attachment;fileName="+realName);
		InputStream is=new FileInputStream(file);
		OutputStream os=rep.getOutputStream();
		//流操作
		IOUtils.copy(is, os);
		//关闭流
		is.close();
		os.close();

	}

}

 <body>
  
   
  	<!--输出所有的学生信息 -->
  	<a  href="add.jsp">添加学生信息</a>

   		<table align="center" border="1" width="70%">
   		<tr>
   			<th>编号</th>
   			<th>姓名</th>
   			<th>年龄</th>
   			<th>分数</th>
   			<th>照片</th>    		
   			<th>更新</th>
   			<th>删除</th>
   		</tr>   		
   		<c:forEach items="${requestScope.stuList2}" var="stu" >
   			<tr>
   				<td>${stu.id}</td>
   				<td>${stu.name }</td>
   				<td>${stu.age }</td>
   				<td>${stu.score}</td>
   				<td><img src="/upload/${stu.photoName }" alt="" /></td>   			
   				<td><a href="servlet/DownloadServlet?idd=${stu.id}">下载</a></td>
   				<td><a href="servlet/StudentServlet?idd=${stu.id}&method=delete">删除</a></td>
   			</tr>   			
   		</c:forEach>    		     			
   	</table>
   
   
  </body>

这是最简单做web项目上传照片的一种简单方法，主要点在控制层，还有更高级的方法，就是利用vsftp以及nginx也是一种方法。