一、文件上传

1.提供表单允许用户通过表单选择文件进行上传

表单必须是POST提交

文件输入框必须有name属性,只有有name属性的输入项浏览器才会进行提交

需要设置enctype属性值为multipart/form-data

POST /Day15/upload.jsp HTTP/1.1

Accept: text/html, application/xhtml+xml, */*

Referer: http://localhost/Day15/upload.jsp

Accept-Language: zh-CN

User-Agent: Mozilla/5.0 (compatible; MSIE 9.0; Windows NT 6.1; Trident/5.0)

Content-Type: multipart/form-data; boundary=---------------------------7de1e62806e0

Accept-Encoding: gzip, deflate

Host: localhost

Content-Length: 394

Connection: Keep-Alive

Cache-Control: no-cache

Cookie: JSESSIONID=818C14110CA7BFD1FC90610866A220E8

-----------------------------7de1e62806e0

Content-Disposition: form-data; name="description1"

xxxx

-----------------------------7de1e62806e0

Content-Disposition: form-data; name="description2"

zzzz

-----------------------------7de1e62806e0

Content-Disposition: form-data; name="file1"; filename="ip.txt"

Content-Type: text/plain

192

-----------------------------7de1e62806e0--

2.在Servlet中将上传的文件保存在服务器的硬盘中

DiskFileItemFactory

public DiskFileItemFactory(int sizeThreshold, java.io.File repository)

public DiskFileItemFactory()

public void setSizeThreshold(int sizeThreshold) --用来设定内存缓冲区的大小,默认是10k

public void setRepository(java.io.File repository) --设定临时文件夹的大小

ServletFileUpload

boolean isMultipartContent(HttpServletRequest request) 判断上传表单是否为multipart/form-data类型

List parseRequest(HttpServletRequest request) 解析request对象，并把表单中的每一个输入项包装成一个fileItem 对象，并返回一个保存了所有FileItem的list集合。

setFileSizeMax(long fileSizeMax) 设置单个上传文件的最大值

setSizeMax(long sizeMax) 设置上传文件总量的最大值

setHeaderEncoding(java.lang.String encoding) 设置编码格式，解决上传文件名乱码问题

setProgressListener(ProgressListener pListener) 实时监听文件上传状态

FileItem

boolean isFormField() 判断FileItem是一个文件上传对象还是普通表单对象

示例代码：

<%@ page language="java" contentType="text/html; charset=UTF-8"    pageEncoding="UTF-8"%>
     
文件上传
     
     
           描述信息1：
             描述信息2：
             
             
      
     

package com.dzq.web;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;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 org.apache.commons.fileupload.FileItem;import org.apache.commons.fileupload.FileUploadException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;import com.dzq.utils.IOUtils;@WebServlet("/UploadFileServlet")public class UploadFileServlet extends HttpServlet {    private static final long serialVersionUID = 1L;              protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        /*InputStream is=request.getInputStream();        byte[] bs=new byte[1024];        int i=0;        while((i=is.read(bs))!=-1){            System.out.write(bs,0,i);        }        is.close();*/                try {            //1.创建工厂            DiskFileItemFactory factory =new DiskFileItemFactory();            //2.生产文件上传核心类            ServletFileUpload fileupload=new ServletFileUpload(factory);            //3.利用文件上传核心类解析request            List
     
       list=fileupload.parseRequest(request);            //4.遍历所有的fileitem            for(FileItem item:list){                if(item.isFormField()){                    //当前是普通字段项                    String name=item.getFieldName();                    String value=item.getString();                    System.out.println(name+":"+value);                }else{                    //当前是一个文件上传项                    String filename=item.getName();                    InputStream in=item.getInputStream();                    OutputStream out=new FileOutputStream(this.getServletContext().getRealPath("/upload"+filename));                    IOUtils.In2Out(in, out);                    IOUtils.close(in, out);                }            }        } catch (Exception e) {            e.printStackTrace();        }    }        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }}
     

package com.dzq.utils;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;        }       }   }}

 

如果是一个普通字段项可以调用:

String getFieldName() 获得普通表单对象的name属性

String getString(String encoding) 获得普通表单对象的value属性，可以用encoding进行编码设置

如果是一个文件上传项:

String getName() 获得上传文件的文件名（有些浏览器会携带客户端路径）

InputStream getInputStream() 获得上传文件的输入流

delete() 在关闭FileItem输入流后，删除临时文件

文件存放应该注意的问题:

1.upload文件夹和temp文件夹都要放在web-inf目录下保护起来,防止上传入侵和访问其他用户上传资源的问题

2.文件名要拼接uuid保证唯一

3.文件要分目录存储保证同一目录下不要有过多的文件,分目录的算法有很多,介绍了一种根据hash值分目录算法

 

文件上传的一些细节：

package com.itheima.web;import java.io.File;import java.io.FileOutputStream;import java.io.IOException;import java.io.InputStream;import java.io.OutputStream;import java.math.BigDecimal;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.ProgressListener;import org.apache.commons.fileupload.FileUploadBase.FileSizeLimitExceededException;import org.apache.commons.fileupload.disk.DiskFileItemFactory;import org.apache.commons.fileupload.servlet.ServletFileUpload;import com.itheima.util.IOUtils;public class UploadServlet extends HttpServlet {    public void doGet(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        response.setContentType("text/html;charset=utf-8");        try{            //1.创建工厂            DiskFileItemFactory factory = new DiskFileItemFactory();            factory.setSizeThreshold(100*1024);            factory.setRepository(new File(this.getServletContext().getRealPath("WEB-INF/temp")));            //2.生产文件上传核心类            ServletFileUpload fileUpload = new ServletFileUpload(factory);                        //--检查是否是正确的文件上传表单            if(!fileUpload.isMultipartContent(request)){                throw new RuntimeException("请用正确的表单进行上传!");            }            //--设置文件上传的大小限制//            fileUpload.setFileSizeMax(1024*1024*100);//单个文件不大于10M//            fileUpload.setSizeMax(1024*1024*100);//总大小不大于100M                        //--设置编码集,解决上传文件名的乱码问题            fileUpload.setHeaderEncoding("utf-8");                        //--设置文件上传监听            fileUpload.setProgressListener(new ProgressListener(){                Long beginTime = System.currentTimeMillis();                public void update(long bytesRead, long contentLength, int items) {                    BigDecimal br = new BigDecimal(bytesRead).divide(new BigDecimal(1024),2,BigDecimal.ROUND_HALF_UP);                    BigDecimal cl = new BigDecimal(contentLength).divide(new BigDecimal(1024),2,BigDecimal.ROUND_HALF_UP);                    System.out.print("当前读取的是第"+items+"个上传项,总大小"+cl+"KB,已经读取"+br+"KB");                    //剩余字节数                    BigDecimal ll = cl.subtract(br);                    System.out.print("剩余"+ll+"KB");                    //上传百分比                    BigDecimal per = br.multiply(new BigDecimal(100)).divide(cl,2,BigDecimal.ROUND_HALF_UP);                    System.out.print("已经完成"+per+"%");                    //上传用时                    Long nowTime = System.currentTimeMillis();                    Long useTime = (nowTime - beginTime)/1000;                    System.out.print("已经用时"+useTime+"秒");                    //上传速度                    BigDecimal speed = new BigDecimal(0);                    if(useTime!=0){                        speed = br.divide(new BigDecimal(useTime),2,BigDecimal.ROUND_HALF_UP);                    }                    System.out.print("上传速度为"+speed+"KB/S");                    //大致剩余时间                    BigDecimal ltime = new BigDecimal(0);                    if(!speed.equals(new BigDecimal(0))){                        ltime = ll.divide(speed,0,BigDecimal.ROUND_HALF_UP);                    }                    System.out.print("大致剩余时间为"+ltime+"秒");                                        System.out.println();                }                            });                        //3.利用文件上传核心类解析request            List
     
       list = fileUpload.parseRequest(request);            //4.遍历所有的FileItem            for(FileItem item : list){                if(item.isFormField()){                    //当前是一个普通的字段项                    String name = item.getFieldName();                    String value = item.getString("utf-8");                    System.out.println(name+":"+value);                }else{                    //当前是一个文件上传项                    String filename = item.getName();                    String uuidName = UUID.randomUUID().toString()+"_"+filename;                                        int hash = uuidName.hashCode();                    String hashStr = Integer.toHexString(hash);                    char [] hss = hashStr.toCharArray();                    String path = this.getServletContext().getRealPath("WEB-INF/upload");                    for(char c : hss){                        path+="/"+c;                    }                    new File(path).mkdirs();                                        InputStream in = item.getInputStream();                    OutputStream out = new FileOutputStream(new File(path,uuidName));                                        IOUtils.In2Out(in, out);                    IOUtils.close(in, out);                                        //--删除临时文件                    item.delete();                }            }        }catch (FileSizeLimitExceededException e) {            response.getWriter().write("单个文件不超过10M,总大小不超过100M!");            return;        }catch (Exception e) {            e.printStackTrace();            throw new RuntimeException(e);        }    }        public void doPost(HttpServletRequest request, HttpServletResponse response)            throws ServletException, IOException {        doGet(request, response);    }}
     

二、文件下载

response.setHeader("Content-Disposition", "attachment;filename="+URLEncoder.encode(filename,"utf-8"));

response.setContentType(this.getServletContext().getMimeType(filename));//MIME类型

 

下载示例源码：

package com.dzq.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.annotation.WebServlet;import javax.servlet.http.HttpServlet;import javax.servlet.http.HttpServletRequest;import javax.servlet.http.HttpServletResponse;import com.dzq.utils.IOUtils;@WebServlet("/DownServlet")public class DownServlet extends HttpServlet {    private static final long serialVersionUID = 1L;              protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        //1.获取要下载的资源的名称             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);        //2.读取资源            }        protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {        doGet(request, response);    }}