Java实现文件上传下载以及查看功能

2024-04-02 19:04:59 956人浏览薄情痞子

Python 官方文档：入门教程 => 点击学习

摘要

目录项目的目录结构代码ioUtils.javaDownServlet.javaUploadHandleServlet.javaWEB.xmlupload.jspdown.jsp运行效

项目的目录结构

代码

IOUtils.java

package cn.edu.zyt.util;

import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;

public class IOUtils {
    private IOUtils() {
    }
    
    public static void In2Out(InputStream in,OutputStream out) throws IOException{
        byte [] bs = new byte[1024];
        int i = 0;
        while((i=in.read(bs))!=-1){
            out.write(bs,0,i);
        }
    }
    
    public static void close(InputStream in,OutputStream out){
        if(in!=null){
            try {
                in.close();
            } catch (IOException e) {
                e.printStackTrace();
            }finally{
                in = null;
            }
        }
        if(out!=null){
            try {
                out.close();
            } catch (IOException e) {
                e.printStackTrace();
            }finally{
                out = null;
            }
        }
    }
}

DownServlet.java

package cn.edu.zyt.web;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
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 cn.edu.zyt.util.IOUtils;

public class DownServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
        String filename = request.getParameter("file");
        
        response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(filename,"utf-8"));
        response.setContentType(this.getServletContext().getMimeType(filename));//MIME类型
        
        InputStream in = new FileInputStream(this.getServletContext().getRealPath(filename));
        OutputStream out = response.getOutputStream();
        IOUtils.In2Out(in, out);
        IOUtils.close(in, null);
    }

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

}

UploadHandleServlet.java

package cn.edu.zyt.web;


import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
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.FileUploadBase;
import org.apache.commons.fileupload.ProgressListener;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;


public class UploadHandleServlet extends HttpServlet {

    public void doGet(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {
                //得到上传文件的保存目录，将上传的文件存放于WEB-INF目录下，不允许外界直接访问，保证上传文件的安全
               String savePath = this.getServletContext().getRealPath("/WEB-INF/upload");
                //上传时生成的临时文件保存目录
                String tempPath = this.getServletContext().getRealPath("/WEB-INF/temp");
                
               
                
                
                File tmpFile = new File(tempPath);
                if (!tmpFile.exists()) {
                    //创建临时目录
                    tmpFile.mkdir();
                }
                
                //消息提示
                String message = "";
                try{
                    //使用Apache文件上传组件处理文件上传步骤：
                    //1、创建一个DiskFileItemFactory工厂
                    DiskFileItemFactory factory = new DiskFileItemFactory();
                    //设置工厂的缓冲区的大小，当上传的文件大小超过缓冲区的大小时，就会生成一个临时文件存放到指定的临时目录当中。
                    factory.setSizeThreshold(1024*100);//设置缓冲区的大小为100KB，如果不指定，那么缓冲区的大小默认是10KB
                    //设置上传时生成的临时文件的保存目录
                    factory.setRepository(tmpFile);
                    //2、创建一个文件上传解析器
                    ServletFileUpload upload = new ServletFileUpload(factory);
                    //监听文件上传进度
                    upload.setProgressListener(new ProgressListener(){
                        public void update(long pBytesRead, long pContentLength, int arg2) {
                            System.out.println("文件大小为：" + pContentLength + ",当前已处理：" + pBytesRead);
                            
                        }
                    });
                     //解决上传文件名的中文乱码
                    upload.setHeaderEncoding("UTF-8"); 
                    //3、判断提交上来的数据是否是上传表单的数据
                    if(!ServletFileUpload.isMultipartContent(request)){
                        //按照传统方式获取数据
                        return;
                    }
                    
                    //设置上传单个文件的大小的最大值，目前是设置为1024*1024字节，也就是1MB
                    upload.setFileSizeMax(1024*1024);
                    //设置上传文件总量的最大值，最大值=同时上传的多个文件的大小的最大值的和，目前设置为10MB
                    upload.setSizeMax(1024*1024*10);
                    //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
                    List<FileItem> list = upload.parseRequest(request);
                    for(FileItem item : list){
                        //如果fileitem中封装的是普通输入项的数据
                        if(item.isFormField()){
                            String name = item.getFieldName();
                            //解决普通输入项的数据的中文乱码问题
                            String value = item.getString("UTF-8");
                            //value = new String(value.getBytes("iso8859-1"),"UTF-8");
                            System.out.println(name + "=" + value);
                        }else{//如果fileitem中封装的是上传文件
                            //得到上传的文件名称，
                            String filename = item.getName();
                            System.out.println(filename);
                            if(filename==null || filename.trim().equals("")){
                                continue;
                            }
                            //注意：不同的浏览器提交的文件名是不一样的，有些浏览器提交上来的文件名是带有路径的，如：  c:\a\b\1.txt，而有些只是单纯的文件名，如：1.txt
                            //处理获取到的上传文件的文件名的路径部分，只保留文件名部分
                            filename = filename.substring(filename.lastIndexOf("\\")+1);
                            //得到上传文件的扩展名
                            String fileExtName = filename.substring(filename.lastIndexOf(".")+1);
                            //如果需要限制上传的文件类型，那么可以通过文件的扩展名来判断上传的文件类型是否合法
                            System.out.println("上传的文件的扩展名是："+fileExtName);
                            //获取item中的上传文件的输入流
                            InputStream in = item.getInputStream();
                            //得到文件保存的名称
                            String saveFilename = makeFileName(filename);
                            //得到文件的保存目录
                            String realSavePath = makePath(saveFilename, savePath);
                            //创建一个文件输出流
                            FileOutputStream out = new FileOutputStream(realSavePath + "\\" + saveFilename);
                            //创建一个缓冲区
                            byte buffer[] = new byte[1024];
                            //判断输入流中的数据是否已经读完的标识
                            int len = 0;
                            //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
                            while((len=in.read(buffer))>0){
                                //使用FileOutputStream输出流将缓冲区的数据写入到指定的目录(savePath + "\\" + filename)当中
                                out.write(buffer, 0, len);
                            }
                            //关闭输入流
                            in.close();
                            //关闭输出流
                            out.close();
                            //删除处理文件上传时生成的临时文件
                            //item.delete();
                            message = "文件上传成功！";
                        }
                    }
                }catch (FileUploadBase.FileSizeLimitExceededException e) {
                    e.printStackTrace();
                    request.setAttribute("message", "单个文件超出最大值！！！");
                    request.getRequestDispatcher("/message.jsp").forward(request, response);
                    return;
                }catch (FileUploadBase.SizeLimitExceededException e) {
                    e.printStackTrace();
                    request.setAttribute("message", "上传文件的总的大小超出限制的最大值！！！");
                    request.getRequestDispatcher("/message.jsp").forward(request, response);
                    return;
                }catch (Exception e) {
                    message= "文件上传失败！";
                    e.printStackTrace();
                }
                request.setAttribute("message",message);
                request.getRequestDispatcher("/message.jsp").forward(request, response);
    }
    
     
    private String makeFileName(String filename){  //2.jpg
        //为防止文件覆盖的现象发生，要为上传文件产生一个唯一的文件名
        return UUID.randomUUID().toString() + "_" + filename;
    }
    
     
    private String makePath(String filename,String savePath){
        //得到文件名的hashCode的值，得到的就是filename这个字符串对象在内存中的地址
        int hashcode = filename.hashCode();
        int dir1 = hashcode&0xf;  //0--15
        int dir2 = (hashcode&0xf0)>>4;  //0-15
        //构造新的保存目录
        String dir = savePath + "\\" + dir1 + "\\" + dir2;  //upload\2\3  upload\3\5
        //File既可以代表文件也可以代表目录
        File file = new File(dir);
        //如果目录不存在
        if(!file.exists()){
            //创建目录
            file.mkdirs();
        }
        return dir;
    }

    public void doPost(HttpServletRequest request, HttpServletResponse response)
            throws ServletException, IOException {

        doGet(request, response);
    }
}

web.xml

<?xml version="1.0" encoding="UTF-8"?>
<web-app xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://java.sun.com/xml/ns/javaee" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" version="2.5">
  
  <servlet>
    <servlet-name>DownServlet</servlet-name>
    <servlet-class>cn.edu.zyt.web.DownServlet</servlet-class>
  </servlet>
  
  <servlet-mapping>
    <servlet-name>DownServlet</servlet-name>
    <url-pattern>/servlet/DownServlet</url-pattern>
  </servlet-mapping>
  
  
  <servlet>
    <servlet-name>UploadHandleServlet</servlet-name>
    <servlet-class>cn.edu.zyt.web.UploadHandleServlet</servlet-class>
</servlet>

<servlet-mapping>
    <servlet-name>UploadHandleServlet</servlet-name>
    <url-pattern>/servlet/UploadHandleServlet</url-pattern>
</servlet-mapping>
</web-app>

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>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
</head>
<body>
    <form
        action="${pageContext.request.contextPath}/servlet/UploadHandleServlet"
        enctype="multipart/form-data" method="post">
        上传用户：<input type="text" name="username"><br /> 上传文件1：<input
            type="file" name="file1"><br /> 上传文件2：<input type="file"
            name="file2"><br /> <input type="submit" value="提交">
    </form>
</body>
</html>

down.jsp

<%@ page language="java" import="java.util.*" pageEncoding="utf-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
</head>
<body>
    <a href="${pageContext.request.contextPath }/1.jpg" rel="external nofollow" >查看美女1号</a>
    <a href="${pageContext.request.contextPath }/1.txt" rel="external nofollow" >查看文件内容</a>
    <a href="${pageContext.request.contextPath }/毛概终版.doc" rel="external nofollow" >毛概终板</a>
    <a
        href="${pageContext.request.contextPath }/servlet/DownServlet?file=2.jpg" rel="external nofollow" >美女2号</a>
    <a
        href="${pageContext.request.contextPath }/servlet/DownServlet?file=1.txt" rel="external nofollow" >文件</a>
    <a
        href="${pageContext.request.contextPath }/servlet/DownServlet?file=result.wav" rel="external nofollow" >视频下载</a>
</body>
</html>