文件的上传和下载

 上传文件的同时，将文件的基本信息添加到数据库中，例如文件名称，文件类型等。
这是jsp显示页面：
enctype="multipart/form-data" method = "post" action = "UploadServlet"name=form1>
上传文件： 红字体为重点！
下面是servlet

package control;

import java.io.*;
import java.sql.Date;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import db.DB;
import db.File1;

public class UploadServlet extends HttpServlet{
    /**
     *
     */
    private static final long serialVersionUID = 1L;

    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException {
        //接收上传文件内容中临时文件的文件名
        String tempFileName = new String("tempFileName");
        //tempfile 对象指向临时文件
        File tempFile = new File("D:/"+tempFileName);
        //outputfile 文件输出流指向这个临时文件
        FileOutputStream outputStream = new FileOutputStream(tempFile);
        //得到客服端提交的所有数据
        InputStream fileSourcel = request.getInputStream();
        //将得到的客服端数据写入临时文件
        byte b[] = new byte[1000];
        int n ;
        while ((n=fileSourcel.read(b))!=-1){
            outputStream.write(b,0,n);
        }

        //关闭输出流和输入流
        outputStream.close();
        fileSourcel.close();

        //randomFile对象指向临时文件
        RandomAccessFile randomFile = new RandomAccessFile(tempFile,"r");
        //读取临时文件的第一行数据
        randomFile.readLine();
        //读取临时文件的第二行数据，这行数据中包含了文件的路径和文件名
        String filePath = randomFile.readLine();
        //得到文件名
        int position = filePath.lastIndexOf('\\');
        CodeToString codeToString = new CodeToString();
        String filename = codeToString.codeString(filePath.substring(position,filePath.length()-1));
        //重新定位读取文件指针到文件头
        randomFile.seek(0);
        //得到第四行回车符的位置，这是上传文件数据的开始位置
        long  forthEnterPosition = 0;
        int forth = 1;
        while((n=randomFile.readByte())!=-1&&(forth<=4)){
            if(n=='\n'){
                forthEnterPosition = randomFile.getFilePointer();
                forth++;
         }
        }

            //生成上传文件的目录
        File fileupLoad = new File("F:/MyEclipse/Manager/WebRoot/file","upLoad");
        fileupLoad.mkdir();
        //saveFile 对象指向要保存的文件
        File saveFile = new File("F:/MyEclipse/Manager/WebRoot/file/upLoad",filename);
        RandomAccessFile randomAccessFile = new RandomAccessFile(saveFile,"rw");
        //找到上传文件数据的结束位置，即倒数第四行
        randomFile.seek(randomFile.length());
        long endPosition = randomFile.getFilePointer();
        int j = 1;
        while((endPosition>=0)&&(j<=4)){
            endPosition--;
            randomFile.seek(endPosition);
            if(randomFile.readByte()=='\n'){
                j++;
         }
        }

        //从上传文件数据的开始位置到结束位置，把数据写入到要保存的文件中
        randomFile.seek(forthEnterPosition);
        long startPoint = randomFile.getFilePointer();
        while(startPoint<endPosition){
            randomAccessFile.write(randomFile.readByte());
            startPoint = randomFile.getFilePointer();
        }

        String a=(String)request.getSession().getAttribute("user_name");
        //Date ct=Date.valueOf(request.getParameter("wpublic_ct"));
        String type =request.getParameter("file_type");
        System.out.println(type);
        File1 jBean=new File1();
        //jBean.setWpublic_ct(ct);
        jBean.setSales_id(a);
        jBean.setFile_type(type);
        jBean.setFile_name(filename);
        String sql = "insert into File1( sales_id,file_type,file_name)values(?,?,?)";
        DB  d =new DB ();
        int count =d.getInsertfile(sql, jBean);
        if(count>0){
        //关闭文件输入、输出
        response.setCharacterEncoding("gbk");
        PrintWriter out = response.getWriter();
        out.print("alert('上传成功！');window.location.href='file.jsp';");


        }


        randomAccessFile.close();
        randomFile.close();
        tempFile.delete(); }



    }

下载：

    ">下载
 
采用超链接方式的下载 若直接单击下载超链接，很可能直接在网页打开了下载的页面。所以应该右键——目标另存为下载！！！

重点代码：

package control;

import java.io.*;
import java.net.URLEncoder;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import db.DB;
public class DownloadServlet extends HttpServlet{
    /**
     *
     */
    private static final long serialVersionUID = 1L;
    public void doPost(HttpServletRequest request, HttpServletResponse response)
    throws ServletException, IOException{
    //获取要下载的文件名
    String filename = "";
    filename = URLEncoder.encode(filename,"UTF-8");
    //得到想客服端输出的输出流
    OutputStream outputStream = response.getOutputStream();
    //输出文件用的字节数组，每次向输出流发送600个字节
    byte b[] = new byte[600];
    //要下载的文件
    File fileload = new File("F:/MyEclipse/Manager/WebRoot/file/upLoad",filename);
    //客服端使用保存文件的对话框
    response.setHeader("Content-disposition", "attachment;filename="+filename);
    //通知客服文件的MIME类型
    response.setContentType("application/msword");
    //通知客服文件的长度
    long fileLength = fileload.length();
    String length = String.valueOf(fileLength);
    response.setHeader("Content_length", length);
    //读取文件，并发送给客服端下载
    FileInputStream inputStream = new FileInputStream(fileload);
    int n = 0;
    while((n=inputStream.read(b))!=-1){
        outputStream.write(b,0,n);
    }

    response.setCharacterEncoding("gbk");
    PrintWriter out = response.getWriter();
    out.print("alert('下载成功！');window.location.href='file.jsp';");
}
    }