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JSP实现快速上传文件的方法

网络编程 2021-07-05 11:23www.168986.cn编程入门
这篇文章主要介绍了JSP实现快速上传文件的方法,实例分析了JSP不使用第三方库实现快速上传文件的完整流程与相关技巧,具有一定参考借鉴价值,需要的朋友可以参考下

本文实例讲述了JSP实现快速上传文件的方法。分享给大家供大家参考。具体如下

这里演示JSP不使用第三方库，实现快速上传文件的功能

1. FileUpload.java

package FileUpload;
import java.io.BufferedOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import javax.servlet.ServletInputStream;
/
  
 /
/
  @author Qch
  
 /
public class FileUpload
{
  ServletInputStream in=null;
  String fpath="C://";
  public FileUpload()
  {
    fpath="C://";
    in=null;
  }
  public void setInputStream(ServletInputStream in)
  {
    this.in=in;
  }
  public void setFpath(String p)
  {
    this.fpath=p;
  }
  public String getFpath()
  {
    return fpath;
  }
  public String getParameter()
  { 
    String r=null;
    try
    {
      r=getParameter(in);
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return r;
  }
  public long getFileUpload()
  {
    long r=-1;
    try
    {
      r=getFileUpload(in,fpath);
    }
    catch (Exception e)
    {
      e.printStackTrace();
    }
    return r;
  }
  public String getParameter(ServletInputStream in)// 只能按顺序提取
      throws Exception
  {
    int l = 0;
    byte[] b = new byte[1024];
    l = in.readLine(b, 0, b.length);// 依次是读取属性的开始符、名称、属性值的类型、属性的值
    String si = new String(b);
    if (si.startsWith("----------------------------"))
    {// 表示是从开始符开始读，否则应为刚读取文件后的一个属性，此时应少读一次
      l = in.readLine(b, 0, b.length);
    }
    l = in.readLine(b, 0, b.length);
    l = in.readLine(b, 0, b.length);
    String value = new String(b, 0, l);
    return value;
  }
  public long getFileUpload(ServletInputStream in, String fpath)// 需要提供输入流和存储路径
      throws Exception
  {
    // out.println("文件信息:<br>");
    long begin = System.currentTimeMillis();// 传送时间计时开始
    int l = 0;
    byte[] b = new byte[1024];
    l = in.readLine(b, 0, b.length);
    String sign = new String(b, 0, l);// eg.-----------------------------7d9dd29630a34
    l = in.readLine(b, 0, b.length);
    String info = new String(b, 0, l);// eg.Content-Disposition:form-data;
    // name="file";
    l = in.readLine(b, 0, b.length);
    // String type=new
    // String(b,0,l);//eg.Content-Type:application/octet-stream(程序文件)
    l = in.readLine(b, 0, b.length);
    // String nulll=new String(b,0,l);//此值应为空
    int nIndex = info.toLowerCase().indexOf("filename=\"");
    int nLastIndex = info.toLowerCase().indexOf("\"", nIndex + 10);
    String filepath = info.substring(nIndex + 10, nLastIndex);
    int na = filepath.lastIndexOf("\\");
    String filename = filepath.substring(na + 1);
    // out.println("文件绝对路径"+filepath+"<br>");
    // out.println("文件名"+filename+"<br><br>");
    String path=fpath + filename;
    File fi = new File(path);// 建立目标文件
    if (!fi.exists()&&!fi.createNewFile())
      return -2;
    BufferedOutputStream f = new BufferedOutputStream(new FileOutputStream(
        fi));
    while ((l = in.readLine(b, 0, b.length)) > 0)
    {
      if (l == sign.length())
      {
        String sign1 = new String(b, 0, sign.length());
        // out.println(sign1+"<br>");
        if (sign1.startsWith(sign))// 比对是否文件已传完
          break;
      }
      f.write(b, 0, l);
      f.flush();
    }
    f.flush();
    f.close();
    long end = System.currentTimeMillis();// 传送时间计时结束
    // out.println("上传文件用时"+(end-begin)+"毫秒<br>");
    return end - begin;
  }
}

2. submitFile.jsp

<%@ page language="java" import="java.util." pageEncoding="GB18030"%>
<%
  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 'submitFile.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">
  -->
    <script language="javascript">
      function check()
      {
        if (document.form2.name.value==""){
          alert("姓名不能为空！！");
          document.form2.name.focus();
          return false;
        }
        if (document.form2.file.value==""){
          alert("文件不能为空！！");
          return false;
        }
        return true;
      }
    </script>
  </head>
  <body>
    <br>
    <form method="post" name="form2" enctype="MULTIPART/FORM-DATA"
      action="AnswerFile.jsp">
      <br>
      <p align="center">
        &nbsp;
        <br>
      </p>
      <table width="530" border="1" bgcolor="#c0c0c0" align="center"
        height="91">
        <tbody>
          <tr>
            <td valign="" align="right">
              姓名
              <br>
            </td>
            <td valign="">
              <input type="text" name="name">
            </td>
          </tr>
          <tr>
            <td align="right">
              &nbsp; 文件
            </td>
            <td align="left">
              &nbsp;
              <input type="file" name="file">
            </td>
          </tr>
          <tr>
            <td valign="" align="right">
              文件类型
              <br>
            </td>
            <td valign="" align="left">
              <select size="1" name="leixing">
                <option selected value="作业">
                  作业
                </option>
                <option value="课程设计">
                  课程设计
                </option>
                <option value="论文">
                  论文
                </option>
              </select>
            </td>
          </tr>
          <tr>
            <td align="right">
              <input type="Submit" value="上传" name="button2" onclick="return(check());">
            </td>
            <td align="left">
              &nbsp;
              <input type="reset" value="重置" name="button3">
            </td>
          </tr>
        </tbody>
      </table>
      <p>
        &nbsp;
        <br>
        <br>
        &nbsp;
      </p>
    </form>
  </body>
</html>

3. AnswerFile.jsp



<%@ page language="java" import="java.util.,java.io."
  pageEncoding="GB18030"%>
<%
  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 'AnswerFile.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>
    <jsp:useBean id="upload" scope="session" class="FileUpload.FileUpload"/>
    <jsp:setProperty name="upload" value="C://" property="fpath"/>
    <%
      ServletInputStream in = request.getInputStream();
      upload.setInputStream(in);
      String nam = upload.getParameter();
      out.println("姓名:" + nam + "<br><br>");
      long time = upload.getFileUpload();
      out.println("文件上传完毕，总共耗时" + time + "毫秒<br>");
      String leixing = upload.getParameter();
      out.println("文件类型" + leixing + "<br>");
      in.close();
    %>
    <br>
    <div align="right">
      <a href="index.jsp">回到首页</a>
    </div>
  </body>
</html>

希望本文所述对大家的JSP程序设计有所帮助。

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