用commonsfileupload1.2 实现文件上传

1.首先，记得导入tomcat下的jar包

jsp代码 uploadSS.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>upload</title>
    </head>

    <body>
        <form action="FileUploadServlet" method="post"
            enctype="multipart/form-data">
            <input type="file" size="30" name="test" />
            <br />
            <input name="up" type="submit" value="上传" />
        </form>
    </body>
</html>

然后编写此页面跳转的servlet

  1 package com.netcloud.upload;
  2 import java.io.File;
  3 import java.io.IOException;
  4 import java.io.PrintWriter;
  5 import java.util.Iterator;
  6 import java.util.List;
  7 
  8 import javax.servlet.ServletException;
  9 import javax.servlet.http.HttpServlet;
 10 import javax.servlet.http.HttpServletRequest;
 11 import javax.servlet.http.HttpServletResponse;
 12 
 13 import org.apache.commons.fileupload.FileItem;
 14 import org.apache.commons.fileupload.FileUploadException;
 15 import org.apache.commons.fileupload.FileUploadBase.SizeLimitExceededException;
 16 import org.apache.commons.fileupload.disk.DiskFileItemFactory;
 17 import org.apache.commons.fileupload.servlet.ServletFileUpload;
 18 //测试成功
 19 public class FileUploadServlet extends HttpServlet {
 20 
 21  public FileUploadServlet() {
 22   super();
 23  }
 24 
 25  public void destroy() {
 26   super.destroy(); // Just puts "destroy" string in log
 27   // Put your code here
 28  }
 29 
 30  public void doGet(HttpServletRequest request, HttpServletResponse response)
 31    throws ServletException, IOException {
 32   doPost(request, response);
 33  }
 34 
 35  public void doPost(HttpServletRequest request, HttpServletResponse response)
 36    throws ServletException, IOException {
 37   final long MAX_SIZE = 3 * 1024 * 1024;// 设置上传文件最大为 3M
 38   // 允许上传的文件格式的列表
 39   final String[] allowedExt = new String[] { "jpg", "jpeg", "gif", "txt",
 40     "doc", "docx", "mp3", "wma", "m4a" };
 41   response.setContentType("text/html");
 42   // 设置字符编码为UTF-8, 这样支持汉字显示
 43   response.setCharacterEncoding("UTF-8");
 44 
 45   // 实例化一个硬盘文件工厂,用来配置上传组件ServletFileUpload
 46   DiskFileItemFactory dfif = new DiskFileItemFactory();
 47   dfif.setSizeThreshold(4096);// 设置上传文件时用于临时存放文件的内存大小,这里是4K.多于的部分将临时存在硬盘
 48   dfif.setRepository(new File(request.getRealPath("/")
 49     + "ImagesUploadTemp"));// 设置存放临时文件的目录,web根目录下的ImagesUploadTemp目录
 50 
 51   // 用以上工厂实例化上传组件
 52   ServletFileUpload sfu = new ServletFileUpload(dfif);
 53   // 设置最大上传尺寸
 54   sfu.setSizeMax(MAX_SIZE);
 55 
 56   PrintWriter out = response.getWriter();
 57   // 从request得到 所有 上传域的列表
 58   List fileList = null;
 59   try {
 60    fileList = sfu.parseRequest(request);
 61   } catch (FileUploadException e) {// 处理文件尺寸过大异常
 62    if (e instanceof SizeLimitExceededException) {
 63     out.println("文件尺寸超过规定大小:" + MAX_SIZE + "字节<p />");
 64     out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
 65     return;
 66    }
 67    e.printStackTrace();
 68   }
 69   // 没有文件上传
 70   if (fileList == null || fileList.size() == 0) {
 71    out.println("请选择上传文件<p />");
 72    out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
 73    return;
 74   }
 75   // 得到所有上传的文件
 76   Iterator fileItr = fileList.iterator();
 77   // 循环处理所有文件
 78   while (fileItr.hasNext()) {
 79    FileItem fileItem = null;
 80    String path = null;
 81    long size = 0;
 82    // 得到当前文件
 83    fileItem = (FileItem) fileItr.next();
 84    // 忽略简单form字段而不是上传域的文件域(<input type="text" />等)
 85    if (fileItem == null || fileItem.isFormField()) {
 86     continue;
 87    }
 88    // 得到文件的完整路径
 89    path = fileItem.getName();
 90    // 得到文件的大小
 91    size = fileItem.getSize();
 92    if ("".equals(path) || size == 0) {
 93     out.println("请选择上传文件<p />");
 94     out.println("<a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
 95     return;
 96    }
 97 
 98    // 得到去除路径的文件名
 99    String t_name = path.substring(path.lastIndexOf("\\") + 1);
100    // 得到文件的扩展名(无扩展名时将得到全名)
101    String t_ext = t_name.substring(t_name.lastIndexOf(".") + 1);
102    // 拒绝接受规定文件格式之外的文件类型
103    int allowFlag = 0;
104    int allowedExtCount = allowedExt.length;
105    for (; allowFlag < allowedExtCount; allowFlag++) {
106     if (allowedExt[allowFlag].equals(t_ext))
107      break;
108    }
109    if (allowFlag == allowedExtCount) {
110     out.println("请上传以下类型的文件<p />");
111     for (allowFlag = 0; allowFlag < allowedExtCount; allowFlag++)
112      out.println("*." + allowedExt[allowFlag]
113        + "&nbsp;&nbsp;&nbsp;");
114     out.println("<p /><a href=\"uploadSS.jsp\" target=\"_top\">返回</a>");
115     return;
116    }
117 
118    long now = System.currentTimeMillis();
119    // 根据系统时间生成上传后保存的文件名
120    String prefix = String.valueOf(now);
121    // 保存的最终文件完整路径,保存在web根目录下的ImagesUploaded目录下
122    String u_name = request.getRealPath("/") + "ImagesUploaded/"
123      + prefix + "." + t_ext;
124    try {
125     // 保存文件
126     fileItem.write(new File(u_name));
127     out.println("文件上传成功. 已保存为: " + prefix + "." + t_ext
128       + " &nbsp;&nbsp;文件大小: " + size + "字节<p />");
129     out.println("<a href=\"uploadSS.jsp\" target=\"_top\">继续上传</a>");
130    } catch (Exception e) {
131     e.printStackTrace();
132    }
133  }
134 
135  }
136 
137  public void init() throws ServletException {
138   // Put your code here
139  }
140 
141 }

注意新建servlet生成的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" xmlns:web="http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" xsi:schemaLocation="http://java.sun.com/xml/ns/javaee http://java.sun.com/xml/ns/javaee/web-app_2_5.xsd" id="WebApp_ID" version="2.5">
  <display-name>TestLearn</display-name>
  <servlet>
    <servlet-name>FileUploadServlet</servlet-name>
    <servlet-class>com.netcloud.upload.FileUploadServlet</servlet-class>
  </servlet>
  <servlet-mapping>
    <servlet-name>FileUploadServlet</servlet-name>
    <url-pattern>/FileUploadServlet</url-pattern>
  </servlet-mapping>
</web-app>

注意：servlet提到的ImagesUploaded ImagesUploadTemp二个文件夹要放在tomcat的目录下

如D:\apache-tomcat-7.0.23\wtpwebapps\TestLearn

2.这是另外一种看起来比较简洁但是实际上跟第一种一样原理的方法：

<%@ 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>→uploadServlet→redult.jsp</title>

</head>
<body>
<form action="uploadServlet" method="POST" enctype="multipart/form-data" >
    upload:<input type="file" name="text" size="30"/> 
    <input type="submit" value="view>>>">
    
</form>

</body>
</html>

跳转的servlet

package com.netcloud.upload;

 

import java.io.File;

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.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;

/**
 * 文件上传如果文件小,上传组件可以将文件存放在内存中,
 * 如果过大时会放在临时目录里面,之后再通过IO流操作
 * @author LEPING LI
 *
 */
@SuppressWarnings("unchecked")
public class uploadServlet extends HttpServlet{
         public void doPost(HttpServletRequest request, HttpServletResponse response)
                            throws ServletException, IOException {
                   request.setCharacterEncoding("UTF-8");
                   //磁盘文件条目工厂
                   DiskFileItemFactory factory=new DiskFileItemFactory();
                    // 文件上传如果文件小,上传组件可以将文件存放在内存中,
                    //如果过大时会放在临时目录里面,之后再通过IO流操作
                   //获取目录真实路径   / 代表 WebRoot目录下面
                   String path=request.getRealPath("/");
                   //设置临时目录
                   factory.setRepository(new File(path));
                   //设置上传文件大小
                   factory.setSizeThreshold(1024*1024);
                   //创建一个ServletFileUpload 实例
                   ServletFileUpload sfu=new ServletFileUpload(factory);
                   try {
                            //解析请求,取得FileItem 列表
                            List<FileItem> lis=sfu.parseRequest(request);
                            //循环遍历
                            for(FileItem item:lis){
                                     //判断是否是简单的表单字段
                                     if(item.isFormField()){
                                               String name=item.getFieldName();
                                               String value=item.getString("UTF-8");
                                               request.setAttribute(name, value);
                                     }else{
                                               //取得字段名
                                               String name=item.getFieldName();
                                               //       取得文件路径名
                                               String value=item.getName();
                                               System.out.println("value:"+value);
                                               //为了屏蔽各个浏览器提供的路径不同异常
                                               int start=value.lastIndexOf("//");
                                               //取得文件名
                                               String fileName=value.substring(start+1);
                                               request.setAttribute(name, fileName);

                                               item.write(new File(path,fileName));   //这句代码与下面高亮显示的代表功能相同
                                         
                                               //获取文件输出流
                                               File f=new File(path,fileName);
                                               OutputStream os=new FileOutputStream(f);
                                               //获取文件条目的输入流
                                               InputStream in=item.getInputStream();
                                               byte[] buffer=new byte[400];
                                               int length=0;
                                               //读写文件
                                               while((length=in.read(buffer))>0){
                                                        os.write(buffer,0,length);
                                               }
                                               os.flush();
                                               os.close();
                                               in.close();
                                              
                                     }
                            }
                   } catch (FileUploadException e) {
                            e.printStackTrace();
                   } catch (Exception e) {
                            e.printStackTrace();
                   }
                   request.getRequestDispatcher("result.jsp").forward(request, response);
         }
}

servlet跳转的result.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>
    文件目录:${requestScope.text }<br>
</body>
</html>

相关阅读:
python3使用PyMysql连接mysql数据库
 MySQL知识总结
 python--正则表达式
 python之多线程
 python在windows和linux环境的进程对比及进程和进程之间的通信
 python基础之生成器（generator）
python基础之动态添加属性和方法
 [STM32F1] 【转】STM32驱动MPU6050
51单片机怎么使用MPU6050读取角度值程序？？
stm32f10x_lib.h
原文地址：https://www.cnblogs.com/cuiyf/p/2934432.html