示例由1个Servlet和3个JSP组成。
1、FileServlet
package com.rk.web.servlet;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
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.FileItemFactory;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import org.apache.commons.fileupload.servlet.ServletFileUpload;
/**
* 处理文件上传与下载
*
*/
public class FileServlet extends HttpServlet {
public void doGet(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 获取请求参数： 区分不同的操作类型
String method = request.getParameter("method");
if ("upload".equals(method)) {
// 上传
upload(request,response);
}
else if ("downList".equals(method)) {
// 进入下载列表
downList(request,response);
}
else if ("down".equals(method)) {
// 下载
down(request,response);
}
}
/**
* 1. 上传
*/
private void upload(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
try {
// 1. 创建工厂对象
FileItemFactory factory = new DiskFileItemFactory();
// 2. 文件上传核心工具类
ServletFileUpload upload = new ServletFileUpload(factory);
// 设置大小限制参数
upload.setFileSizeMax(10*1024*1024); // 单个文件大小限制
upload.setSizeMax(50*1024*1024); // 总文件大小限制
upload.setHeaderEncoding("UTF-8"); // 对中文文件编码处理
// 判断
if (upload.isMultipartContent(request)) {
// 3. 把请求数据转换为list集合
List<FileItem> list = upload.parseRequest(request);
// 遍历
for (FileItem item : list){
// 判断：普通文本数据
if (item.isFormField()){
// 获取名称
String name = item.getFieldName();
// 获取值
String value = item.getString();
System.out.println(value);
}
// 文件表单项
else {
/******** 文件上传 ***********/
// a. 获取文件名称
String name = item.getName();
// ----处理上传文件名重名问题----
// a1. 先得到唯一标记
String id = UUID.randomUUID().toString();
// a2. 拼接文件名
name = id + "#" + name;
// b. 得到上传目录
String basePath = getServletContext().getRealPath("/upload");
// c. 创建要上传的文件对象
File file = new File(basePath,name);
// d. 上传
item.write(file);
item.delete(); // 删除组件运行时产生的临时文件
}
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 2. 进入下载列表
*/
private void downList(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 实现思路：先获取upload目录下所有文件的文件名，再保存；跳转到down.jsp列表展示
//1. 初始化map集合Map<包含唯一标记的文件名, 简短文件名> ;
Map<String,String> fileNames = new HashMap<String,String>();
//2. 获取上传目录，及其下所有的文件的文件名
String bathPath = getServletContext().getRealPath("/upload");
// 目录
File file = new File(bathPath);
// 目录下，所有文件名
String list[] = file.list();
// 遍历，封装
if (list != null && list.length > 0){
for (int i=0; i<list.length; i++){
// 全名
String fileName = list[i];
// 短名
String shortName = fileName.substring(fileName.lastIndexOf("#")+1);
// 封装
fileNames.put(fileName, shortName);
}
}
// 3. 保存到request域
request.setAttribute("fileNames", fileNames);
// 4. 转发
request.getRequestDispatcher("/downlist.jsp").forward(request, response);
}
/**
* 3. 处理下载
*/
private void down(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
// 获取用户下载的文件名称(url地址后追加数据,get)
String fileName = request.getParameter("fileName");
fileName = new String(fileName.getBytes("ISO8859-1"),"UTF-8");
// 先获取上传目录路径
String basePath = getServletContext().getRealPath("/upload");
// 获取一个文件流
InputStream in = new FileInputStream(new File(basePath,fileName));
// 如果文件名是中文，需要进行url编码
fileName = URLEncoder.encode(fileName, "UTF-8");
// 设置下载的响应头
response.setHeader("content-disposition", "attachment;fileName=" + fileName);
// 获取response字节流
OutputStream out = response.getOutputStream();
byte[] b = new byte[1024];
int len = -1;
while ((len = in.read(b)) != -1){
out.write(b, 0, len);
}
// 关闭
out.close();
in.close();
}
public void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
this.doGet(request, response);
}
}
2、index.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>index</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<a href="${pageContext.request.contextPath }/upload.jsp">文件上传</a>
<a href="${pageContext.request.contextPath }/fileServlet?method=downList">文件下载</a>
</body>
</html>
3、upload.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>upload</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<form name="frm_test" action="${pageContext.request.contextPath }/fileServlet?method=upload" method="post" enctype="multipart/form-data">
<%--<input type="hidden" name="method" value="upload">--%>
用户名：<input type="text" name="userName"> <br/>
文件： <input type="file" name="file_img"> <br/>
<input type="submit" value="提交">
</form>
</body>
</html>
4、downlist.jsp
<%@ page language="java" import="java.util.*" pageEncoding="UTF-8"%>
<%@taglib uri="http://java.sun.com/jsp/jstl/core" prefix="c" %>
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN">
<html>
<head>
<title>下载列表</title>
<meta http-equiv="pragma" content="no-cache">
<meta http-equiv="cache-control" content="no-cache">
<meta http-equiv="expires" content="0">
</head>
<body>
<table border="1" align="center">
<tr>
<th>序号</th>
<th>文件名</th>
<th>操作</th>
</tr>
<c:forEach var="en" items="${requestScope.fileNames}" varStatus="vs">
<tr>
<td>${vs.count }</td>
<td>${en.value }</td>
<td>
<%--<a href="${pageContext.request.contextPath }/fileServlet?method=down&..">下载</a>--%>
<!-- 构建一个地址 -->
<c:url var="url" value="fileServlet">
<c:param name="method" value="down"></c:param>
<c:param name="fileName" value="${en.key}"></c:param>
</c:url>
<!-- 使用上面地址 -->
<a href="${url }">下载</a>
</td>
</tr>
</c:forEach>
</table>
</body>
</html>
时间： 2024-07-30 13:47:53