使用数据库和javabean实现上传与下载

首先，我是部分参考网址，其中写的最好的莫过于https://blog.csdn.net/a15920804969/article/details/78497668

总体构造图

（1）domain

file.java

package download_upload.domian;

import lombok.AllArgsConstructor;

import lombok.Data;

import lombok.NoArgsConstructor;

@Data

@AllArgsConstructor

public class file {

private Long id;

private String uuidname;

private String filename;

private String savepath;

private String uploadtime;

private String description;

private String username;

public file(){}

public file(String uuidname, String filename, String savepath, String uploadtime, String description,

String username) {

super();

this.uuidname = uuidname;

this.filename = filename;

this.savepath = savepath;

this.uploadtime = uploadtime;

this.description = description;

this.username = username;

}

前端页面

index.jsp

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

pageEncoding="UTF-8"%>

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

</body>

</html>

upload.jsp

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

pageEncoding="UTF-8"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

<!--

privateString savepath; //记住文件的位置

privateDate uploadtime; //文件的上传时间

privateString description; //文件的描述

-->

<table>

<tr>

<td>上传文件名</td><td><input type="file"name="filename"></td>

</tr>

<tr>

</tr>

<tr>

</tr>

<tr>

</tr>

</table>

</form>

</body>

</html>

message.jsp

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

pageEncoding="UTF-8"%>

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

${message}

</body>

</html>

list.jsp

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

pageEncoding="UTF-8"%>

<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c"%>

<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">

<html>

<head>

<title>Insert title here</title>

</head>

<body>

<tr>

<th>上传者</th><th>上传文件名</th><th>上传时间</th><th>文件位置</th><th>文件描述</th><th>下载</th>

</tr>

<c:forEach var="file" items="${list }">

<tr>

<td>${file.username }</td>

<td>${file.filename }</td>

<td>${file.uploadtime }</td>

<td>${file.savepath }</td>

<td>${file.description }</td>

</tr>

</c:forEach>

</table>

</body>

</html>

type接口的编写

type.java

package download_upload.javabean;

import java.sql.ResultSet;

public interface type <T>{

T hanlder(ResultSet rs)throws Exception;

}

javabeanlist的编写

javabeanlist.java

import java.beans.BeanInfo;

import java.beans.Introspector;

import java.beans.PropertyDescriptor;

import java.sql.ResultSet;

import java.util.ArrayList;

import java.util.List;

import org.omg.CORBA.PRIVATE_MEMBER;

public class javabeanlist<T>implements type<List<T>> {

private Class<T>classtype;

public javabeanlist(Class<T>classtype) {

this.classtype=classtype;

}

@Override

public List<T> hanlder(ResultSet rs) throws Exception {

// TODO Auto-generated method stub

List<T>list=new ArrayList<>();

while(rs.next())

{

T obj=classtype.newInstance();

BeanInfo beanInfo=Introspector.getBeanInfo(classtype,Object.class);

PropertyDescriptor[] pro=beanInfo.getPropertyDescriptors();

for(PropertyDescriptor ps:pro)

{

String name=ps.getName();

Object value=rs.getObject(name);

ps.getWriteMethod().invoke(obj, value);

}

list.add(obj) ;

}

return list;

}

Javabean的编写

javabean.java

package download_upload.javabean;

import java.beans.BeanInfo;

import java.beans.Introspector;

import java.beans.PropertyDescriptor;

import java.sql.ResultSet;

public class javabean<T> implements type<T>{

private Class<T>classtype;

public javabean(Class<T>classtype) {

// TODO Auto-generated constructor stub

this.classtype=classtype;

}

@Override

public T hanlder(ResultSet rs) throws Exception {

// TODO Auto-generated method stub

if(rs.next())

{

T obj=classtype.newInstance();

BeanInfo beanInfo=Introspector.getBeanInfo(classtype,Object.class);

PropertyDescriptor[] pro=beanInfo.getPropertyDescriptors();

for(PropertyDescriptor ps:pro)

{

String name=ps.getName();

Object value=rs.getObject(name);

ps.getWriteMethod().invoke(obj, value);

}

return obj;

}

return null;

}

模板类的编写

template.java

package download_upload.template;

import java.sql.Connection;

import java.sql.PreparedStatement;

import java.sql.ResultSet;

import java.sql.SQLException;

import download_upload.javabean.type;

import download_upload.utils.utils;

/*DML操作*/

public class template {

public static int DMLoperator(String sql,Object...param) {

Connection conn=utils.conn();

PreparedStatement ps=null;

try {

ps=conn.prepareStatement(sql);

for(int i=0;i<param.length;i++) {

ps.setObject(i+1,param[i]);

}

return ps.executeUpdate();

} catch (SQLException e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

utils.close(conn,ps,null);

}

return 0;

}

/*DQL操作*/

public static <T>T DQLoperator(String sql,type<T> type,Object...para){

Connection conn=utils.conn();

PreparedStatement ps=null;

ResultSet re=null;

try {

ps=conn.prepareStatement(sql);

for(int i=0;i<para.length;i++) {

ps.setObject(i+1, para[i]);

}

re=ps.executeQuery();

return type.hanlder(re);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}finally {

utils.close(conn, ps, re);

}

return null;

}

utils工具类

utils.java

package download_upload.utils;

import java.io.InputStream;

import java.sql.Connection;

import java.sql.ResultSet;

import java.sql.SQLException;

import java.sql.Statement;

import java.util.Properties;

import javax.sql.DataSource;

import com.alibaba.druid.pool.DruidDataSourceFactory;

public class utils {

private static DataSource datasource;

static{

Properties pro=new Properties();

ClassLoader cla=Thread.currentThread().getContextClassLoader();

InputStream in=cla.getResourceAsStream("db.properties");

try {

pro.load(in);

Class.forName(pro.getProperty("driverClassName"));

datasource=DruidDataSourceFactory.createDataSource(pro);

} catch (Exception e) {

// TODO Auto-generated catch block

e.printStackTrace();

}

public static Connection conn() {

try {

return datasource.getConnection();

} catch (SQLException e) {

// TODO Auto-generated catch block

throw new RuntimeException("数据库连接异常");

}

public static void close(Connection conn,Statement st,ResultSet re) {

try {

if(re!=null)

re.close();

} catch (Exception e2) {

// TODO: handle exception

e2.printStackTrace();

}

finally {

try {

if(st!=null)

st.close();

} catch (Exception e3) {

// TODO: handle exception

e3.printStackTrace();

}finally {

try {

if(conn!=null)

conn.close();

} catch (Exception e4) {

// TODO: handle exception

e4.printStackTrace();

}

webutils工具类

webutils.java

package download_upload.servlet;

import java.io.File;

import java.io.FileOutputStream;

import java.io.InputStream;

import java.io.OutputStream;

import java.util.Date;

import java.util.List;

import java.util.UUID;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import org.apache.commons.beanutils.BeanUtils;

import org.apache.commons.fileupload.FileItem;

import org.apache.commons.fileupload.FileUploadBase;

import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException;

import org.apache.commons.fileupload.disk.DiskFileItemFactory;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

import download_upload.domian.file;

public class webutils {

public static file doFileUpload(HttpServletRequest req) throws FileSizeLimitExceededException {

file fud = new file();// 文件信息对象

try {

DiskFileItemFactory factory = new DiskFileItemFactory();

// 临时文件夹temp

factory.setRepository(new File(req.getSession().getServletContext().getContextPath()+"/temp"));

// factory.setRepository(new File("/temp"));// 临时文件夹temp

factory.setSizeThreshold(1024 * 1024);// 临时缓冲区大小为1M

ServletFileUpload parse = new ServletFileUpload(factory);// 解析器

//上传文件大小

parse.setFileSizeMax(1024 * 1024 * 2);// 单个文件大小限制为2M

parse.setSizeMax(1024 * 1024 * 20);// 总的文件大小限制为20M

//解决中文文件名的乱码

parse.setHeaderEncoding("utf-8");

List<FileItem> list = parse.parseRequest(req);

for (FileItem fileItem : list) {

// 普通表单

if (fileItem.isFormField()) {

String fieldName = fileItem.getFieldName();

// String value = fileItem.getString();

String value = fileItem.getString("utf-8");// 解决字段的中文乱码问题

System.out.println("fieldName:" + fieldName);

System.out.println("value:" + value);

// 将当前字段封装到fud对象中对应的字段中去

//普通字段都通过这个保存到fud中

BeanUtils.setProperty(fud, fieldName, value);

}

// 文件

else {

String filename = fileItem.getName();// 获取文件名

//文件名：aa.txt 与c:\a\b\c\aa.txt的处理统一

int index=filename.lastIndexOf("\\");

if(index!=-1){

filename=filename.substring(index+1);

}

String realPath=req.getSession().getServletContext().getRealPath("/wenjian/upload");

//生成随机文件夹

String savePath=generateSavePath(realPath,filename);

//生成唯一的文件名

String uuidname=generateUUIDName(filename);

// 上传文件

InputStream in = fileItem.getInputStream();// 获取文件读取流

// OutputStream out = new FileOutputStream("d:/" + name);

//保存文件夹：savePath 唯一文件名：uuidname

OutputStream out = new FileOutputStream(new File(savePath,uuidname));

byte[] buf = new byte[1024];

int len = 0;

while ((len = in.read(buf)) != -1) {

out.write(buf, 0, len);

}

in.close();

out.close();

//删除临时文件

fileItem.delete();

fud.setFilename(filename);//文件名

fud.setUuidname(uuidname);//唯一文件名

fud.setSavepath(savePath);//保存路径

fud.setUploadtime(new Date().toLocaleString());

}

return fud;//返回文件信息封装对象

} catch (FileUploadBase.FileSizeLimitExceededException e) {

// e.printStackTrace();//仅仅只是打印异常错误信息

//使用失败，因为此处并没有response

// request.setAttribute("message", "对不起，您上传的文件大小超过了大小的限制");

// request.getRequestDispatcher("/message.jsp").forward(request,response);

//怎么办？

//抛出一个异常出去实际上异常也是一个返回值

//抛异常【编译时异常还是运行时异常】

//编译时异常

throw e;//记得抛出异常要在方法中进行声明

}

catch(Exception e){

throw new RuntimeException(e);//抛出运行时异常

}

//生成唯一的文件名

private static String generateUUIDName(String filename) {

return UUID.randomUUID().toString()+"_"+filename;

}

//生成随机文件夹

private static String generateSavePath(String realPath, String filename) {

int hashCode=filename.hashCode();

//通过位运算，计算出一级和二级目录的数字

int first=hashCode & (0xf);//以及目录

int second=(hashCode>>4)&(0xf);//二级目录

String savePath=realPath+"/"+first+"/"+second;

File f=new File(savePath);

if(!f.exists()){

f.mkdirs();//创建多级目录

}

return savePath;//保存路径

}

DAO设计模式

ifile.java

package download_upload.impl.filedao;

import java.util.List;

import download_upload.domian.file;

public interface Ifile {

public void insert(file fud);//上传文件

public List<file> list();//查询文件

public file select(Long id);//通过id获得文件的全部信息

}

fileimpl.java

package download_upload.impl;

import java.util.List;

import download_upload.javabean.javabean;

import download_upload.javabean.javabeanlist;

import download_upload.domian.file;

import download_upload.impl.filedao.Ifile;

import download_upload.template.template;

public class fileimpl implements Ifile{

@Override

public void insert(file fud) {

// TODO Auto-generated method stub

String sql="INSERT INTO baocun (uuidname,filename,savepath,uploadtime,description,username)VALUES(?,?,?,?,?,?)";

template.DMLoperator(sql, fud.getUuidname(),fud.getFilename(),fud.getSavepath(),fud.getUploadtime(),fud.getDescription(),fud.getUsername());

}

@Override

public List<file> list() {

// TODO Auto-generated method stub

String sql="SELECT *FROM baocun";

return template.DQLoperator(sql, new javabeanlist<>(file.class));

}

@Override

public file select(Long id) {

// TODO Auto-generated method stub

String sql="SELECT *FROM baocun where id=?";

return template.DQLoperator(sql, new javabean<>(file.class),id);

}

db.properties

#key=value

driverClassName=com.mysql.jdbc.Driver

url=jdbc:mysql://localhost:3306/upload?rewriteBatchedStatements=true

username=root

password=123456

maxActive=5

servlet的编写

down.java

package download_upload.servlet;

import java.io.File;

import java.io.FileInputStream;

import java.io.IOException;

import java.io.InputStream;

import java.io.OutputStream;

importjava.net.URLEncoder;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import download_upload.domian.file;

import download_upload.impl.fileimpl;

import download_upload.impl.filedao.Ifile;

@WebServlet("/download")

public class down extends HttpServlet{

/**

private Ifile ifile;

private static final long serialVersionUID = 1L;

@Override

public void init() throws ServletException {

// TODO Auto-generated method stub

ifile=new fileimpl();

}

@Override

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

// TODO Auto-generated method stub

String id = req.getParameter("id");

file fud=ifile.select(Long.valueOf(id));//通过id获取文件相关信息

String path=fud.getSavepath();//保存路径

String uuidname=fud.getUuidname();//保存文件名

File f=new File(path,uuidname);//要下载的文件的存放位置 path/name

//健壮性判断

if(!f.exists()){

req.setAttribute("message", "对不起，当前文件已删除");

req.getRequestDispatcher("/message.jsp").forward(req, resp);

}

//将中文的文件名编码后再放到http的响应头中去，编码之后浏览器收到后会自动解码

String filename=URLEncoder.encode(fud.getFilename(),"utf-8");

//设置参数，使得浏览器可以以下载的方式打开文件。

resp.setHeader("content-disposition", "attachement;filename="+filename);

//将要下载的文件当做一个inputStream读取进来

InputStream in=new FileInputStream(f);

//读进来后，再写到response.getOutputStream()去就可以了

//相应的数据

OutputStream out=resp.getOutputStream();

byte[] buf=new byte[1024];

int len=0;

while((len=in.read(buf))!=-1){

out.write(buf, 0, len);

System.out.println(buf);

System.out.println(len);

}

in.close();

out.close();

System.out.println("下载文件成功");

}

downtown.java

package download_upload.servlet;

import java.io.IOException;

import java.util.List;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import download_upload.impl.fileimpl;

import download_upload.impl.filedao.Ifile;

@WebServlet("/listfile")

public class download extends HttpServlet{

private Ifile file;

@Override

public void init() throws ServletException {

// TODO Auto-generated method stub

file=new fileimpl();

}

@Override

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

// TODO Auto-generated method stub

List list=file.list();

req.setAttribute("list", list);

req.getRequestDispatcher("/list.jsp").forward(req, resp);

}

upload.java

package download_upload.servlet;

import java.io.IOException;

import javax.servlet.ServletException;

import javax.servlet.annotation.WebServlet;

import javax.servlet.http.HttpServlet;

import javax.servlet.http.HttpServletRequest;

import javax.servlet.http.HttpServletResponse;

import org.apache.commons.fileupload.servlet.ServletFileUpload;

import download_upload.domian.file;

import download_upload.impl.fileimpl;

import download_upload.impl.filedao.Ifile;

import net.sf.json.util.WebUtils;

@WebServlet("/upload")

public class upload extends HttpServlet{

@Override

protected void service(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {

// TODO Auto-generated method stub

if (!ServletFileUpload.isMultipartContent(req)) {

req.setAttribute("message", "不是请求的信息表单，请确认表单属性是否正确");

req.getRequestDispatcher("/message.jsp").forward(req,resp);

return;

}

try {

//调用工具类，获得上传文件信息

file fud=webutils.doFileUpload(req);

Ifile wenjian=new fileimpl();

wenjian.insert(fud);

req.setAttribute("message", "上传文件成功");

req.getRequestDispatcher("/message.jsp").forward(req,resp);

} catch (Exception e) {

req.setAttribute("message", "对不起，您上传的文件大小超过了大小的限制");

req.getRequestDispatcher("/message.jsp").forward(req,resp);

}

使用数据库和javabean实现上传与下载

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