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JAVA使用commos-fileupload实现文件上传与下载实例解析

作者：森林森 时间：2022-07-08 03:47:13　

首先给大家介绍一文件的上传

实体类


import java.sql.Timestamp;
/**
*
* @Decription 文件上传实体类
*
*/
public class Upfile {
private String id;// ID主键 使用uuid随机生成
private String uuidname; // UUID名称
private String filename;//文件名称
private String savepath; // 保存路径
private Timestamp uploadtime; // 上传时间
private String description;// 文件描述
private String username; // 用户名
public Upfile() {
super();
}
public Upfile(String id, String uuidname, String filename, String savepath,
Timestamp uploadtime, String description, String username) {
super();
this.id = id;
this.uuidname = uuidname;
this.filename = filename;
this.savepath = savepath;
this.uploadtime = uploadtime;
this.description = description;
this.username = username;
}
public String getDescription() {
return description;
}
public String getFilename() {
return filename;
}
public String getId() {
return id;
}
public String getSavepath() {
return savepath;
}
public Timestamp getUploadtime() {
return uploadtime;
}
public String getUsername() {
return username;
}
public String getUuidname() {
return uuidname;
}
public void setDescription(String description) {
this.description = description;
}
public void setFilename(String filename) {
this.filename = filename;
}
public void setId(String id) {
this.id = id;
}
public void setSavepath(String savepath) {
this.savepath = savepath;
}
public void setUploadtime(Timestamp uploadtime) {
this.uploadtime = uploadtime;
}
public void setUsername(String username) {
this.username = username;
}
public void setUuidname(String uuidname) {
this.uuidname = uuidname;
}
}

页面


<％@ 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 'upload.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>
<h1>文件上传</h1>
<form action="${pageContext.request.contextPath }/upload" method="post" enctype="multipart/form-data">
<table>
<tr>
<td> 上传用户名:</td>
<td><input type="text" name="username"/></td>
</tr>
<tr>
<td> 上传文件:</td>
<td><input type="file" name="file"/></td>
</tr>
<tr>
<td> 描述:</td>
<td><textarea rows="5" cols="50" name="description"></textarea></td>
</tr>
<tr>
<td><input type="submit" value="上传开始"/></td>
</tr>
</table>
</form>
<div>${msg }</div>
<a href="${pageContext.request.contextPath }/index.jsp">返回主页</a>
</body>
</html>

Servlet


import java.io.IOException;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import com.itheima.domain.Upfile;
import com.itheima.exception.MyException;
import com.itheima.service.UpfileService;
import com.itheima.service.impl.UpfileServiceImpl;
import com.itheima.untils.WebUntil;
public class UploadFileServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//判断表单是不是多个部分组成的
if(!ServletFileUpload.isMultipartContent(request)){
request.setAttribute("msg", "表单个设置错误,请检查enctype属性是是否设置正确");
request.getRequestDispatcher("/upload.jsp").forward(request, response);
return ;
}
//是多部分组成的就获取并遍历返回一个文件上传对象,包含上传的所有信息
try {
Upfile upfile=WebUntil.upload(request);
UpfileService upfileService=new UpfileServiceImpl();
boolean flag=upfileService.add(upfile);
if(flag){
request.setAttribute("msg", "上传成功");
request.getRequestDispatcher("/upload.jsp").forward(request, response);
return ;
}else{
request.setAttribute("msg", "上传失败,请重试");
request.getRequestDispatcher("/upload.jsp").forward(request, response);
return ;
}
}catch (FileSizeLimitExceededException e) {
e.printStackTrace();
request.setAttribute("msg", "单个文件大小 ,超过最大限制");
request.getRequestDispatcher("/upload.jsp").forward(request, response);
return ;
} catch (SizeLimitExceededException e) {
e.printStackTrace();
request.setAttribute("msg", "总文件大小 ,超过最大限制");
request.getRequestDispatcher("/upload.jsp").forward(request, response);
return ;
}
}
}

工具类


import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.util.ArrayList;
import java.util.List;
import java.util.UUID;
import javax.servlet.http.HttpServletRequest;
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileUploadBase;
import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
import com.itheima.domain.Upfile;
import com.itheima.exception.MyException;
/**
* 文件上传工具类
* @Decription TODO
*
*/
public class WebUntil {
/**
* 文件上传的方法
* @param request 请求参数传入
* @return 返回一个Upfile对象
* @throws FileSizeLimitExceededException
* @throws SizeLimitExceededException
* @throws IOException
*/
public static Upfile upload(HttpServletRequest request) throws FileSizeLimitExceededException, SizeLimitExceededException {
Upfile upfile=new Upfile();
ArrayList<String> fileList=initList();
try {
//获取磁盘文件对象工厂
DiskFileItemFactory factory=new DiskFileItemFactory();
String tmp=request.getSession().getServletContext().getRealPath("/tmp");
System.out.println(tmp);
//初始化工厂
setFactory(factory,tmp);
//获取文件上传解析器
ServletFileUpload upload=new ServletFileUpload(factory);
//初始化解析器
setUpload(upload);
//获取文件列表集合
List<FileItem> list = upload.parseRequest(request);
//遍历
for (FileItem items : list) {
//判断 是不是普通表单个对象
if(items.isFormField()){
//获取上传表单的name
String fieldName=items.getFieldName();
//value
String fieldValue=items.getString("UTF-8");
//判断
if("username".equals(fieldName)){
//设置
upfile.setUsername(fieldValue);
}else if("description".equals(fieldName)){
//设置属性
upfile.setDescription(fieldValue);
}
}else{
//是文件就准备上传
//获取文件名
String filename=items.getName();
//处理因为浏览器不同而导致的 获得 的 文件名的 差异
int index=filename.lastIndexOf("\\");
if(index!=-1){
filename=filename.substring(index+1);
}
//生成随机的文件名
String uuidname=generateFilename(filename);
//获取上传的文件路径
String savepath=request.getSession().getServletContext().getRealPath("/WEB-INF/upload");
//获取请求对象中的输入流
InputStream in = items.getInputStream();
//将文件打散存放在不同的路径,求出路径
savepath=generateRandomDir(savepath,uuidname);
//复制文件
uploadFile(in,savepath,uuidname);
String id=UUID.randomUUID().toString();
upfile.setId(id);
upfile.setSavepath(savepath);
upfile.setUuidname(uuidname);
upfile.setFilename(filename);
//清除缓存
items.delete();
}
}
}catch ( FileUploadBase.FileSizeLimitExceededException e) {
//抛出出异常
throw e;
} catch (FileUploadBase.SizeLimitExceededException e) {
//抛出出异常
throw e;
}catch (FileUploadException e) {
e.printStackTrace();
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
} catch (Exception e) {
e.printStackTrace();
}
return upfile;
}
/**
* 初始化文件列表
* @return
*/
private static ArrayList<String> initList() {
ArrayList<String> list=new ArrayList<String>();
list.add(".jpg");
list.add(".rar");
list.add(".txt");
list.add(".png");
return list;
}
/**
* 复制文件
* @param in items中的输入流
* @param savepath 保存路径
* @param uuidname 文件名
*/
private static void uploadFile(InputStream in, String savepath,
String uuidname) {
//获取文件
File file=new File(savepath, uuidname);
OutputStream out = null;
try {
int len=0;
byte [] buf=new byte[1024];
//获取输出流
out = new FileOutputStream(file);
while((len=in.read(buf))!=-1){
out.write(buf, 0, len);
}
} catch (FileNotFoundException e) {
e.printStackTrace();
} catch (IOException e) {
e.printStackTrace();
}finally{
try {
in.close();
} catch (IOException e) {
e.printStackTrace();
}
try {
out.close();
} catch (IOException e) {
e.printStackTrace();
}
}
}
/**
* 生成随机的存放路径
* @param savepath 保存路径
* @param uuidname 生成的uuid名称
* @return
* 使用hashcode完成
*/
private static String generateRandomDir(String savepath, String uuidname) {
//转化为hashcode
System.out.println("上传路径"+savepath);
System.out.println("UUIDNAME"+uuidname);
int hashcode=uuidname.hashCode();
//容器
StringBuilder sb=new StringBuilder();
while(hashcode>0){
//与上15
int tmp=hashcode&0xf;
sb.append("/");
sb.append(tmp+"");
hashcode=hashcode>>4;
}
//拼接新的路径
String path=savepath+sb.toString();
System.out.println("path"+path);
File file=new File(path);
//判断路径存不存在
if(!file.exists()){
//不存在就创建
file.mkdirs();
}
//返回保存路径
return path;
}
/**
* 生成新的文件名
* @param uuidname 随机的ID名字
* @param filename 原来的名
* @return
*/
private static String generateFilename( String filename) {
String uuidname=UUID.randomUUID().toString();
return uuidname.replace("-", "").toString()+"_"+filename;
}
/**
* 初始化解析器
* @param upload
*/
private static void setUpload(ServletFileUpload upload) {
// 设置 字符编码
upload.setHeaderEncoding("utf-8");
//设置文件大小
upload.setFileSizeMax(1024*1024*20);
//设置总文件大小
upload.setSizeMax(1024*1024*50);
//设置进度 *
upload.setProgressListener(new ProgressListener() {
public void update(long pBytesRead, long pContentLength, int pItems) {
System.out.println("已经读取: "+pBytesRead+",总共有: "+pContentLength+", 第"+pItems+"个");
}
});
}
/**
* 工厂初始化方法
* @param factory
* @param tmp 缓冲目录
*/
private static void setFactory(DiskFileItemFactory factory, String tmp) {
/// 配置初始化值缓冲区
factory.setSizeThreshold(1024*1024);
File file=new File(tmp);
//设置缓冲目录
factory.setRepository(file);
}
}

二文件下载

Servlet


public class DownupfileServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
doPost(request, response);
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
//获取ID
String id=request.getParameter("id");
//业务层的接口
UpfileService upfileService=new UpfileServiceImpl();
//根据ID查找这个对象
Upfile upfile=upfileService.findUpfileById(id);
if(upfile==null){
return;
}
//获取文件的真实名称
String filename=upfile.getFilename();
//如果文件名中有中文,需要转码,不然就下载时没有文件名
filename=URLEncoder.encode(filename, "utf-8");
//更改过的名称
String uuidname=upfile.getUuidname();
//保存路径
String savepath=upfile.getSavepath();
File file=new File(savepath,uuidname);
//判断文件 是否存在
if(!file.exists()){
request.setAttribute("msg", "下载 的文件过期了");
request.getRequestDispatcher("/index").forward(request, response);
return;
}
//设置文件下载响应头信息
response.setHeader("Content-disposition", "attachement;filename="+filename);
//使用IO流输出
InputStream in = new FileInputStream(file);
ServletOutputStream out = response.getOutputStream();
int len=0;
byte [] buf=new byte[1024];
while((len=in.read(buf))!=-1){
out.write(buf, 0, len);
}
in.close();
}
}

数据库


create database upload_download_exercise;
use upload_download_exercise;
create table upfiles(
id varchar(100), //使用UUID生成
uuidname varchar(255),//uuid加上原来的文件名
filename varchar(100),//真实文件名
savepath varchar(255),//保存路径
uploadtime timestamp,//上传时间
description varchar(255),//描述
username varchar(10) 上传人
);

以上所述是小编给大家分享的JAVA使用commos-fileupload实现文件上传与下载的相关内容，希望对大家有所帮助。

标签：java,文件上传,文件下载
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