发布于 2016-07-25 09:13:32 | 75 次阅读 | 评论: 0 | 来源: 网友投递

这里有新鲜出炉的Java设计模式,程序狗速度看过来!

Java程序设计语言

java 是一种可以撰写跨平台应用软件的面向对象的程序设计语言,是由Sun Microsystems公司于1995年5月推出的Java程序设计语言和Java平台(即JavaEE(j2ee), JavaME(j2me), JavaSE(j2se))的总称。


这篇文章主要介绍了JAVA使用commos-fileupload实现文件上传与下载的相关资料,需要的朋友可以参考下

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); 
//设置进度监听器 
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。



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