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servlet实现文件上传、预览、下载、删除功能

作者:Marydon

这篇文章主要为大家详细介绍了servlet实现文件上传、预览、下载、删除功能,文中示例代码介绍的非常详细,具有一定的参考价值,感兴趣的小伙伴们可以参考一下

servlet实现文件上传,预览,下载和删除,供大家参考,具体内容如下

一、准备工作:

  1.1 文件上传插件:uploadify;

  1.2 文件上传所需jar包:commons-fileupload-1.3.1.jar和commons-io-2.2.jar

  1.3 将数据转成JSON对象需要jar包:commons-beanutils-1.8.3.jar、commons-collections-3.2.1.jar、commons-lang-2.6.jar、commons-logging-1.1.3.jar、ezmorph-1.0.6.jar和json-lib-2.4-jdk15.jar

  1.4 开发工具:我用的是Eclipse,随意

  1.5 目录结构

需要注意的是:变更uploadify.css文件中的取消文件上传图片的路径

.uploadify-queue-item .cancel a {
 background: url('../images/uploadify-cancel.png') 0 0 no-repeat;
 float: right;
 height: 16px;
 text-indent: -9999px;
 width: 16px;
} 

二、代码展示

2.1 客户端代码设计

JSP部分

<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
 <head> 
  <title>演示-操作文件</title>
  <%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
  <script type="text/javascript" src="<c:url value="/js/jquery-1.11.2.min.js"/>"></script>
  <script type="text/javascript" src="<c:url value="/uploadify/js/jquery.uploadify-3.2.1.min.js"/>"></script>
  <link href="<c:url value=" rel="external nofollow" /uploadify/css/uploadify.css"/>" type="text/css" rel="stylesheet"/>
  <script type="text/javascript">var baseUrl = '<%=request.getContextPath()%>';</script>
  <script type="text/javascript" src="<c:url value="/index.js"/>"></script>
  <style type="text/css">
   /* 上传、取消上传按钮style start */
   .Button {
    width: 80px;
    margin: 3px 1px 0 5px;
    padding: 0 10px;
    background-color: #16a0d3;
    border: none;
    display: inline-block;
    font-family: "Microsoft Yahei";
    font-size: 14px;
    cursor: pointer;
    height: 30px;
    line-height: 30px;
    color: #FFF;
    border-radius: 5px;
    text-decoration:none;
    text-align:center;
   }
   
   .ButtonOver {
    width: 80px;
    margin: 3px 1px 0 5px;
    padding: 0 10px;
    background-color: #117ea6;
    border: none;
    display: inline-block;
    font-family: "Microsoft Yahei";
    font-size: 14px;
    cursor: pointer;
    height: 30px;
    line-height: 30px;
    color: #FFF;
    border-radius: 5px;
    text-decoration:none;
    text-align:center;
   } 
   /* end 上传、取消上传按钮style */
  </style>
 </head>
 <body>
  <!-- 文件上传 -->
  <div id="file_upload"></div>
  <div id="ctrlUpload" style="display:none;">
   <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" onclick="$('#file_upload').uploadify('upload', '*');" class="Button" 
    onmouseover="javascript:this.className='ButtonOver'" onmouseout="javascript:this.className='Button'">
      上传所有
   </a> 
   <a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" onclick="$('#file_upload').uploadify('cancel', '*');$('#ctrlUpload').hide();" class="Button"
    onmouseover="javascript:this.className='ButtonOver'" onmouseout="javascript:this.className='Button'">
      取消上传
   </a> 
  </div>
  <table border=1 style="border-collapse: collapse;" id="tableFiles">
   <thead>
    <th>序号</th>
    <th>文件名</th>
    <th>文件预览</th>
    <th>文件下载</th>
    <th>文件删除</th>
   </thead>
   <tbody></tbody>
  </table>
 </body>
</html>

js文件

var operateFile = new OperateFile();
window.onload = function() {
 operateFile.init();
 
}

/**
 * 对文件进行操作
 * @returns
 */
function OperateFile() {
 var object = this;
 
 /**
  * 初始化操作:
  */
 this.init = function() {
  // 队列中的文件数
  var selectedCount = 0;
  $('#file_upload').uploadify({
   'method' : 'get',// 默认值post,设置成get是为了向后台传递自定义的参数
   'auto' : false,// 设置为true当选择文件后就直接上传了,为false需要点击上传按钮才上传。默认值为TRUE
   'buttonText' : '添加文件',// 按钮文本
   'fileTypeExts' : '*.gif; *.jpg; *.png;*.pdf;*.zip;',// 限制上传文件类型,默认值没有限制(*.*)
   'fileTypeDesc' : '请选择gif jpg png pdf zip类型的文件',// 这个属性值必须设置fileTypeExts属性后才有效,用来设置选择文件对话框中的提示文本,默认值:All Files
   'swf' : baseUrl + '/uploadify/flash/uploadify.swf', // flash文件路径(帮助我们与后端交互数据)
   'uploader' : baseUrl + '/uploadFile.do' , // 处理文件上传请求地址 
   'formData' : {'param1':'测试文件上传'},// 请求参数:上传每个文件的同时提交到服务器的额外数据
   'onDialogClose' : function(queueData) {
    // 获取该队列中有多少个要上传的文件 
    var queueSize = $('#file_upload-queue').children('div').length;
    if (queueSize > 0) {
     $('#ctrlUpload').show();
    }
   },
   'onUploadSuccess' : function(file, data, response) {// 上传成功
    // 将josn字符串转换成JSON对象
    data = eval('(' + data + ')');
    // 获取页面上文件展示table 有多少行
    var rowsLength = $('#tableFiles')[0].rows.length;
    // 设置查看文件所需参数
    var param = "fileName=" + data.fileName;
    // 查看文件请求地址
    var viewUrl = baseUrl + '/viewFile.do?' + param;
    // 下载文件请求地址
    var downloadUrl = baseUrl + '/downloadFile.do?' + param;
    
    // 拼接一行tr
    var trTemplate = '<tr>'
        + '<td>'
        +  rowsLength  
        + '</td>'
        + '<td>'
        +  file.name // 仍展示原文件名
        + '</td>'
        + '<td>'
        +  '<a href="' + viewUrl + '" rel="external nofollow" target="_blank">点击预览</a>'
        +  '<input type="hidden" name="imgAddress" value="' + data.fileName + '"/>'
        + '</td>'
        + '<td>'
        +  '<a href="' + downloadUrl + '" rel="external nofollow" >点击下载</a>'
        + '</td>'
        + '<td>'
        +  '<a href="javascript:;" rel="external nofollow" rel="external nofollow" rel="external nofollow" onclick="operateFile.deleteFile(\'' + data.fileName + '\',' + rowsLength +');">点击删除</a>'
        + '</td>'
        +'</tr>';
    $('#tableFiles').append(trTemplate);
   },
   'onUploadError' : function(file, errorCode, errorMsg, errorString) {// 上传失败
    
   }
  });
  
 }
 
 /**
  * 删除文件
  * @param 文件名
  */
 this.deleteFile = function(fileName,rowIndex) {
  // 设置删除文件所需参数
  var param = "fileName=" + fileName;
  // 删除文件请求地址
  var deleteUrl = baseUrl + '/deleteFile.do?' + param;
  $.get(
   deleteUrl, 
   function(msg) {
    alert(msg);
    if ("删除失败!" != msg) {
     // 删除该行记录
     $('#tableFiles')[0].deleteRow(rowIndex);
    }
   }
  );
  
 }
 
} 

2.2 服务器端代码设计

文件上传代码(FileUpload.javae文件)

package controller.fileHandler;

import java.io.File;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.HashMap;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import javax.servlet.ServletContext;
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;
import net.sf.json.JSONObject;

public class FileUpload extends HttpServlet {
 private static final long serialVersionUID = 1L;

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

 /**
  * 处理文件上传的post
  * @precaution 下方的类名出自包import org.apache.commons.fileupload.*
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // 1.设置参数编码
  request.setCharacterEncoding("UTF-8");
  // 设置响应数据字符集
  response.setCharacterEncoding("UTF-8");
  // 设置响应数据格式
  // response.setContentType("application/json; charset=UTF-8");
  PrintWriter out = response.getWriter();
  // 2.创建文件上传处理工厂
  DiskFileItemFactory factory = new DiskFileItemFactory();
  // 3.设置临时文件存放地点
  // 3.1获取当前web应用程序对象(WEB容器在启动时,它会为每个WEB应用程序都创建一个对应的ServletContext对象,它代表当前web应用)
  ServletContext servletContext = this.getServletConfig().getServletContext();
  // 3.2获取服务器的临时目录(tomcat、WebLogic)
  // D:\ProgramFiles(x86)\APACHE\TOMCAT\apache-tomcat-7.0.40-x86\work\Catalina\localhost\demo
  File repository = (File) servletContext.getAttribute("javax.servlet.context.tempdir");
  // 3.3临时文件将会存储在该目录下
  factory.setRepository(repository);
  // 4.创建文件上传处理器
  ServletFileUpload upload = new ServletFileUpload(factory);
  // 5.判断请求类型是否为文件上传类型
  boolean multipartContent = upload.isMultipartContent(request);

  Map<String, String> mapData = new HashMap<String, String>();
  // 返回信息
  String msg = "";
  // 错误信息
  String errorMsg = "";
  // 文件名
  String fileName = "";
  if (multipartContent) {
   try {
    // 获取请求参数
    String param = request.getParameter("param1");
    System.out.println(param);
    // 6.解析请求信息
    List<FileItem> items = upload.parseRequest(request);

    // 7.对所有请求信息进行判断
    Iterator<FileItem> iter = items.iterator();
    while (iter.hasNext()) {
     FileItem item = iter.next();
     // 信息为文件格式
     if (!item.isFormField()) {
      fileName = processUploadedFile(param, item);
      msg = "上传成功!";
     }
    }
   } catch (FileUploadException e) {
    e.printStackTrace();
    msg = "上传失败!";
    errorMsg = e.getMessage();
   }

  } else {
   msg = "form表单类型不是multipart/form-data,无法上传!";
  }

  mapData.put("msg", msg);
  mapData.put("errorMsg", errorMsg);
  mapData.put("fileName", fileName);
  // 将Map转成JSON
  JSONObject jsonData = JSONObject.fromObject(mapData);
  // 返回客户端信息
  out.print(jsonData.toString());
 }

 /**
  * 处理上传的文件
  * @param ORG_ID
  * @param order
  * @param item
  */
 @SuppressWarnings("unused")
 private String processUploadedFile(String param, FileItem item) {
  // Process a file upload
  String fieldName = item.getFieldName();// 默认值为Filedata
  // 获取文件名
  String fileName = item.getName();
  // 内容类型:application/octet-stream
  String contentType = item.getContentType();
  boolean isInMemory = item.isInMemory();
  // 获取文件大小
  long sizeInBytes = item.getSize();
  // 1.指定文件上传的根路径
  String path = this.getServletContext().getRealPath("/WEB-INF/uploadFiles");
  // 2.路径构成:/uploadfile/fileName
  // TODO 可以自定义文件存放路径
  // 3.根据路径批量创建文件夹
  File fileDirectories = new File(path);
  // 目录不存在时,再创建
  if (!fileDirectories.exists()) {
   fileDirectories.mkdirs();// 所有的文件夹都创建成功才返回TRUE
  }
  // 4.文件名格式校验(文件名中不能包含#号)
  int index = fileName.indexOf("#");
  if (index > -1) {
   fileName = fileName.replace('#', '_');
  }
  // TODO 可以对文件名进行重命名
  // 5.在指定路径下创建指定名称的文件
  File uploadedFile = new File(path + "/" + fileName);
  // 6.判断该文件是否已存在
  if (!uploadedFile.exists()) {
   try {
    // 使用了这个方法写入文件,临时文件会被系统自动删除
    item.write(uploadedFile);
   } catch (Exception e) {
    e.printStackTrace();
   }
  }
  // 返回重名后的文件名
  return fileName;
 }

 /**
  * 处理信息为普通的格式
  * @param item
  */
 private void processFormField(FileItem item) {
  // Process a regular form field
  if (item.isFormField()) {
   String name = item.getFieldName();
   String value = item.getString();
  }
 }
}

文件查看代码(FileView.java文件)

package controller.fileHandler;

import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FileView extends HttpServlet {
 private static final long serialVersionUID = 1L;

 // 设定输出的类型
 private static final String GIF = "image/gif;charset=UTF-8";
 private static final String JPG = "image/jpeg;charset=UTF-8";
 private static final String PNG = "image/png;charset=UTF-8";
 private static final String PDF = "application/pdf;charset=UTF-8";
 private static final String ZIP = "application/zip;charset=UTF-8";

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

 /**
  * 处理文件查看的post
  * @throws IOException
  * @precaution 下方的类名出自包import org.apache.commons.fileupload.*
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // 文件流
  InputStream is = null;
  // 输入缓冲流
  BufferedInputStream bis = null;
  // 得到输出流
  OutputStream output = null;
  // 输出缓冲流
  BufferedOutputStream bos = null;
  // 1.设置参数编码
  request.setCharacterEncoding("UTF-8");
  // 2.设置响应数据字符集
  response.setCharacterEncoding("UTF-8");
  // 3.获取客户端请求参数:文件名
  String fileName = request.getParameter("fileName");
  // 4.重置response
  response.reset();
  // 5.设置响应数据格式
  if (fileName.endsWith(".gif")) {
   response.setContentType(GIF);
  } else if (fileName.endsWith(".jpg")) {
   response.setContentType(JPG);
  } else if (fileName.endsWith(".png")) {
   response.setContentType(PNG);
  } else if (fileName.endsWith(".pdf")) {
   response.setContentType(PDF);
  } else if (fileName.endsWith(".gif")) {
   response.setContentType(GIF);
  } else if (fileName.endsWith(".zip")) {
   response.setContentType(ZIP);
  }

  String filePath = "WEB-INF/uploadFiles/" + fileName;
  // 获取当前web应用程序
  ServletContext webApp = this.getServletContext();
  // 6.获取指定文件上传的真实路径
  filePath = webApp.getRealPath(filePath);
  // 7.读取目标文件,通过response将目标文件写到客户端
  is = new FileInputStream(filePath);
  bis = new BufferedInputStream(is);
  output = response.getOutputStream();
  bos = new BufferedOutputStream(output);
  byte data[] = new byte[1024];// 缓冲字节数
  int size = bis.read(data);
  while (size != -1) {
   bos.write(data, 0, size);
   size = bis.read(data);
  }

  // 关闭流
  bis.close();
  bos.flush();// 清空输出缓冲流
  bos.close();
  output.close();
 }

}

文件下载代码(FileDownload.java文件)

package controller.fileHandler;

import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FileDownload extends HttpServlet {
 private static final long serialVersionUID = 1L;

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

 /**
  * 处理文件下载的post
  * @throws IOException
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // 1.设置参数编码
  request.setCharacterEncoding("UTF-8");
  // 设置响应数据字符集
  response.setCharacterEncoding("UTF-8");
  // 1.获得请求文件名
  String fileName = request.getParameter("fileName");
  // 2.设置文件MIME类型(指定要返回内容的类型)
  response.setContentType(getServletContext().getMimeType(fileName));
  // 3.设置Content-Disposition(指定下载该文件时的文件名)
  response.setHeader("content-disposition", "attachment;filename=" + fileName);
  // 4.读取目标文件,通过response将目标文件写到客户端
  // 4.1 获取目标文件的绝对路径
  String filePath = "WEB-INF/uploadFiles/" + fileName;
  filePath = this.getServletContext().getRealPath(filePath);
  // 4.2 读取文件
  InputStream in = new FileInputStream(filePath);
  // 4.3 输出文件
  OutputStream out = response.getOutputStream();
  // 写文件
  int n;
  while ((n = in.read()) != -1) {
   out.write(n);
  }

  in.close();
  out.close();
 }

}

文件删除代码(FileDelete.java文件)

package controller.fileHandler;

import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

public class FileDelete extends HttpServlet {
 private static final long serialVersionUID = 1L;

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

 /**
  * 处理文件下载的post
  * @throws IOException
  */
 protected void doPost(HttpServletRequest request, HttpServletResponse response)
   throws ServletException, IOException {
  // 1.设置参数编码
  request.setCharacterEncoding("UTF-8");
  // 设置响应数据字符集
  response.setCharacterEncoding("UTF-8");
  // 2.获得请求文件名
  String fileName = request.getParameter("fileName");
  // 3.获取该文件所在路径
  String filePath = "WEB-INF/uploadFiles/" + fileName;
  filePath = this.getServletContext().getRealPath(filePath);
  // 4.在指定路径下创建指定名称的文件
  File deleteFile = new File(filePath);
  boolean flag = false;
  String msg = "";
  // 5.判断该文件是否已存在
  if (deleteFile.exists()) {
   flag = deleteFile.delete();
   if (flag) {
    msg = "删除成功!";
   } else {
    msg = "删除失败!";
   }
  } else {
   msg = "该文件不存在!";
  }

  // 6.返回客户端操作信息
  response.getWriter().print(msg);
 }

}

web.xml代码

<?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" id="WebApp_ID" version="2.5">
 <display-name>demo_uploadAndDownload</display-name>
 <context-param>
  <param-name>webAppRootKey</param-name>
  <param-value>uploadAndDownload</param-value>
 </context-param>
 <!-- 处理文件的Servlet -->
 <!-- 文件上传 Start -->
 <servlet>
  <servlet-name>upload</servlet-name>
  <!-- 配置处理文件上传的java类 -->
  <servlet-class>controller.fileHandler.FileUpload</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>upload</servlet-name>
  <!-- 设置文件上传请求路径 -->
  <url-pattern>/uploadFile.do</url-pattern>
 </servlet-mapping>
 <!-- End 文件上传 -->
 <!-- 文件预览 Start -->
 <servlet>
  <servlet-name>view</servlet-name>
  <!-- 配置处理文件预览的java类 -->
  <servlet-class>controller.fileHandler.FileView</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>view</servlet-name>
  <!-- 设置文件预览请求路径 -->
  <url-pattern>/viewFile.do</url-pattern>
 </servlet-mapping>
 <!-- End 文件预览 -->
 <!-- 文件下载 Start -->
 <servlet>
  <servlet-name>download</servlet-name>
  <!-- 配置处理文件下载的java类 -->
  <servlet-class>controller.fileHandler.FileDownload</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>download</servlet-name>
  <!-- 设置文件下载请求路径 -->
  <url-pattern>/downloadFile.do</url-pattern>
 </servlet-mapping>
 <!-- End 文件下载 -->
 <!-- 文件删除 Start -->
 <servlet>
  <servlet-name>delete</servlet-name>
  <!-- 配置处理文件删除的java类 -->
  <servlet-class>controller.fileHandler.FileDelete</servlet-class>
 </servlet>
 <servlet-mapping>
  <servlet-name>delete</servlet-name>
  <!-- 设置文件删除请求路径 -->
  <url-pattern>/deleteFile</url-pattern>
 </servlet-mapping>
 <!-- End 文件删除 -->
 <welcome-file-list>
  <welcome-file>index.html</welcome-file>
  <welcome-file>index.htm</welcome-file>
  <welcome-file>index.jsp</welcome-file>
  <welcome-file>default.html</welcome-file>
  <welcome-file>default.htm</welcome-file>
  <welcome-file>default.jsp</welcome-file>
 </welcome-file-list>
</web-app>

2.3 代码优化

处理文件查看(FileView.java) ,设置响应文件类型,可以用下面这句话替换

response.setContentType(getServletContext().getMimeType(fileName) + ";charset=UTF-8");

三、效果展示

以上就是本文的全部内容,希望对大家的学习有所帮助,也希望大家多多支持脚本之家。

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