上传文件,上传文件太大怎么办

上传文件,上传文件太大怎么办,文件的上传与下载(一)

在实现文件上传和下载之前我们需要做一些准备工作,在Apache官网去下载文件上传下载的两个组件,下载链接这里给出:common-fileupload组件下载:http://commons.apache.org/proper/commons-fileupload/

common-io组件下载:http://commons.apache.org/proper/commons-io/根据自己需求下载对应版本

一、创建工程

将所需要的两个开发包导入到工程项目中如图:

上传文件,上传文件太大怎么办

二、代码编写

1.前端页面代码

1). 在WebRoot目录下新建一个fileUpload.jsp页面,用来上传文件

 1 %@ page language="java" import="java.util.*" pageEncoding="GB18030"% 
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 % 
 7 !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 8 html 
 9 head 
10 base href=" %=basePath% " 
12 title My JSP 'fileUpload.jsp' starting page /title 
14 meta http-equiv="pragma" content="no-cache" 
15 meta http-equiv="cache-control" content="no-cache" 
16 meta http-equiv="expires" content="0" 
17 meta http-equiv="keywords" content="keyword1,keyword2,keyword3" 
18 meta http-equiv="description" content="This is my page" 
19 !--
20 link rel="stylesheet" type="text/css" href="styles.css" 
21 -- 
23 /head 
25 body 
26 !-- 文件上传表单的提交方式必须是“post” 编码类型必须为:enctype="multipart/form-data" -- 
27 form action="UploadServlet" method="post" enctype="multipart/form-data" 
29 username: input type="text" name="username" / br 
30 file: input type="file" name="file" br 
31 file2: input type="file" name="file2" br 
32 input type="submit" value="上传文件" 
34 /form 
36 /body 
37 /html 

2). 新建一个fileUploadResult.jsp页面用来显示结果信息

 1 %@ page language="java" import="java.util.*,java.io.*" pageEncoding="GB18030"% 
 3 String path = request.getContextPath();
 4 String basePath = request.getScheme()+"://"+request.getServerName()+":"+request.getServerPort()+path+"/";
 5 % 
 7 !DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" 
 8 html 
 9 head 
10 base href=" %=basePath% " 
12 title My JSP 'fileUploadResult.jsp' starting page /title 
14 meta http-equiv="pragma" content="no-cache" 
15 meta http-equiv="cache-control" content="no-cache" 
16 meta http-equiv="expires" content="0" 
17 meta http-equiv="keywords" content="keyword1,keyword2,keyword3" 
18 meta http-equiv="description" content="This is my page" 
19 !--
20 link rel="stylesheet" type="text/css" href="styles.css" 
21 -- 
23 /head 
25 body 
26 %-- 
28 //获取流对象
29 InputStream inputStream = request.getInputStream();
31 BufferedReader br = new BufferedReader(new InputStreamReader(inputStream));
33 String buffer = null;
35 while((buffer = br.readLine()) != null){
36 out.print(buffer + " br ");
39 br.close();
40 inputStream.close();
42 % 
43 --% 
44 ${message} br 
46 EL-username : ${requestScope.username} br 
47 EL-file1 : ${requestScope.file } br 
48 EL-file2 : ${requestScope.file2} br 
50 /body 
51 /html 

2. 编写上传文件处理的Servlet代码

1) UploadServlet.java代码如下:

 1 package com.Servlet;
 3 import java.io.File;
 4 import java.io.FileOutputStream;
 5 import java.io.IOException;
 6 import java.io.InputStream;
 7 import java.io.PrintWriter;
 8 import java.util.List;
 10 import javax.servlet.ServletException;
 11 import javax.servlet.http.HttpServlet;
 12 import javax.servlet.http.HttpServletRequest;
 13 import javax.servlet.http.HttpServletResponse;
 15 import org.apache.commons.fileupload.FileItem;
 16 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
 17 import org.apache.commons.fileupload.servlet.ServletFileUpload;
 19 public class UploadServlet extends HttpServlet {
 21 /**
 22 * The doPost method of the servlet. br 
 23 *
 24 * This method is called when a form has its tag value method equals to post.
 25 * 
 26 * @param request the request send by the client to the server
 27 * @param response the response send by the server to the client
 28 * @throws ServletException if an error occurred
 29 * @throws IOException if an error occurred
 30 */
 31 public void doPost(HttpServletRequest request, HttpServletResponse response)
 32 throws ServletException, IOException {
 35 //得到上传文件的保存目录,将上传的文件放在webRoot目录下(但是一般为了安全放在WEB-INF目录下,不允许外界直接访问,保证上传的安全)
 36 String path = this.getServletContext().getRealPath("/upload");
 38 File file = new File(path);
 40 //判断上传文件的保存目录是否存在
 41 if(!file.exists() !file.isDirectory()){
 42 System.out.println(path + "目录不存在,需要创建!");
 43 //创建目录
 44 file.mkdir();
 45 }
 46 //消息提示
 47 String message = "";
 48 try{
 49 //使用Apache文件上传组件处理文件上传步骤:
 50 //1.创建一个DiskFileItemFactory工厂
 51 DiskFileItemFactory factory = new DiskFileItemFactory();
 52 //2.创建一个文件上传解析器
 53 ServletFileUpload upload = new ServletFileUpload(factory);
 54 //解决中文乱码
 55 upload.setHeaderEncoding("UTF-8");
 56 //3.判断提交的数据普通表单的数据还是带文件上传的表单
 57 if(!upload.isMultipartContent(request)){
 58 //如果是表单数据普通表单,则按照传统方式获取数据
 59 return ; 
 60 }
 61 //4.使用ServletFileUpload解析器解析上传数据,解析结果返回的是一个List FileItem 集合,每一个FileItem对应一个Form表单的输入项
 62 List FileItem list = upload.parseRequest(request);
 63 for(FileItem item : list){
 64 //如果fileItem中封装的是普通输入项的数据
 65 if(item.isFormField()){
 66 //获取字段名字
 67 String name = item.getFieldName();
 68 //解决普通输入项中中文乱码问题
 69 String value = item.getString("UTF-8");//value = new String(value.getBytes("iso8859-1"),"UTF-8");
 70 System.out.println(name + " = " + value);
 71 }else{ //如果表单中提交的是上传文件
 72 //获得上传的文件名称
 73 String filename = item.getName();
 74 System.out.println(filename);
 75 if(filename == null || filename.trim().equals(" ")){
 76 continue;
 77 }
 78 //注意:不同的浏览器提交的文件名称是不一样的,有些浏览器提交的文件会带有路径,如“D:\\project\WebRoot\hello.jsp”,有一些是单纯的文件名:hello.jsp
 79 //去掉获取到文件名中的路径名,保留单纯的文件名
 80 filename = filename.substring(filename.lastIndexOf("\\") + 1);
 81 //获取item中的上传文件的输入流
 82 InputStream in = item.getInputStream();
 83 //创建一个文件输入流
 84 FileOutputStream out = new FileOutputStream(path + "\\" + filename);
 85 //创建一个缓冲区
 86 byte buffer[] = new byte[1024];
 87 //判断输入流中的数据是否已经读取完毕的标志位
 88 int len = 0;
 89 //循环将输入流读入到缓冲区当中,(len = in.read(buffer) 0)就表示in里面还有数据存在
 90 while((len = in.read(buffer)) 0){
 91 //使用FileOutputStream输出流将缓冲区的数据写入到指定的目录(path+"\\"+filename)当中
 92 out.write(buffer, 0, len);
 93 }
 94 //关闭输入流
 95 in.close();
 96 //关闭输出流
 97 out.close();
 98 //删除处理文件上传生成的临时文件
 99 item.delete();
100 message = "文件上传成功!";
103 }
104 }
106 }catch(Exception e){
107 message = "文件上传失败!";
108 e.printStackTrace();
109 }
111 request.setAttribute(message, message);
112 request.getRequestDispatcher("fileUploadResult.jsp").forward(request, response);
114 }
116 }

2)web.xml文件中的配置

 1 ?xml version="1.0" encoding="UTF-8"? 
 2 web-app version="3.0"
 3 xmlns="http://java.sun.com/xml/ns/javaee"
 4 xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
 5 xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_3_0.xsd" 
 6 servlet 
 8 servlet-name UploadServlet /servlet-name 
 9 servlet-class com.Servlet.UploadServlet /servlet-class 
10 /servlet 
12 servlet-mapping 
13 servlet-name UploadServlet /servlet-name 
14 url-pattern /UploadServlet /url-pattern 
15 /servlet-mapping 
17 /web-app 

结果:

上传文件,上传文件太大怎么办

上传文件,上传文件太大怎么办

 

摘自:https://www.cnblogs.com/xdp-gacl/p/4200090.html