将之前上传的文件在页面里遍历显示出来：
ListFileServlet
package com.chinasofti.UploadServlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;
/**
* Created by yvettee on 2017/10/13.
*/
//列出网站所有文件
@WebServlet(name = "ListFileServlet", urlPatterns = "/listFileServlet")
public class ListFileServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
String path = this.getServletContext().getRealPath("/WEB-INF/upload");
Map map = new HashMap();
listFile(new File(path), map);
request.setAttribute("map", map);
request.getRequestDispatcher("/listFile.jsp").forward(request, response);
}
//如何保存递归出来的资源
public void listFile(File file, Map map) {
if (!file.isFile()) {//判断是否是文件
File[] children = file.listFiles();//得到子级目录
for (File f : children) {
listFile(f, map);//递归
}
} else {
String fileName = file.getName().substring(file.getName().indexOf("_") + 1);
map.put(file.getName(), fileName);//<a href="/servlet?fileName=文件在服务器的名称">文件的原始文件名</a>
}
}
}
listFile.jsp
<%--
Created by IntelliJ IDEA.
User: yvettee
Date: 2017/10/13
Time: 17:02
To change this template use File | Settings | File Templates.
--%>
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<html>
<head>
<title>文件预览</title>
</head>
<body>
下载文件有：<br>
<c:forEach var="entry" items="${requestScope.map}">
<c:url var="url" value="/downloadServlet">
<c:param name="fileName" value="${entry.key}"></c:param>
</c:url>
${entry.value} <a href="${url}">下载</a><br>
</c:forEach>
</body>
</html>
下载：
package com.chinasofti.UploadServlet;
import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.File;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.net.URLEncoder;
/**
* Created by yvettee on 2017/10/13.
*/
@WebServlet(name = "DownloadServlet", urlPatterns = "/downloadServlet")
public class DownloadServlet extends HttpServlet {
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
//得到文件名(URL的)
String fileName = request.getParameter("fileName");
//中文要设置编码（get方式请求的）
fileName = new String(fileName.getBytes("iso8859-1"), "UTF-8");
System.out.println("文件名=" + fileName);
//找出这个文件
String path = this.getServletContext().getRealPath("/WEB-INF/upload") + File.separator + getPath(fileName);
System.out.println("path=" + path);
File file = new File(path + File.separator + fileName);
System.out.println("路径=" + file.getAbsolutePath());
if (!file.exists()) {
request.setAttribute("message", "对不起，您要访问的资源不存在。");
request.getRequestDispatcher("/message.jsp").forward(request, response);
return;
}
//得到文件的原始文件名
String oldName = file.getName().substring(file.getName().indexOf("_") + 1);
System.out.println("oldName = " + oldName);
//通知浏览器以下载方式打开下面发送的数据
response.setHeader("content-disposition", "attachment;filename=" + URLEncoder.encode(oldName, "UTF-8"));
FileInputStream in = new FileInputStream(file);
int len = 0;
byte buffer[] = new byte[1024];
OutputStream out = response.getOutputStream();
while ((len = in.read(buffer)) > 0) {
out.write(buffer, 0, len);
}
in.close();
}
public String getPath(String fileName) {
int hashCode = fileName.hashCode();
int dir1 = hashCode & 0xf;
int dir2 = (hashCode >> 4) & 0xf;
return dir1 + File.separator + dir2;
}
}
源代码：https://github.com/yvettee36/UploadFile
上篇：http://www.jianshu.com/p/4c398d00c5df
下篇：http://www.jianshu.com/p/f9e18ff6ceb3
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