java文件下载
网上有很多文件下载的实现，但很多都存在一些问题，我在写的时候也遇到了问题，如文件乱码，为防以后再犯所以就有了这篇文章，废话不说，直接贴码
servlet中
@Override
protected void doPost(HttpServletRequest request, HttpServletResponse response)
throws ServletException, IOException {
String fileName = URLDecoder.decode(request.getParameter("fileName"), "UTF-8");
System.out.println(fileName);
String filePath = FileUtil.UPLOAD_PATH + "\\" + fileName;//下载文件路径
if (request.getHeader("User-Agent").toUpperCase().indexOf("MSIE") > 0)
fileName = URLEncoder.encode(fileName, "UTF-8");//IE浏览器
else
fileName = new String(fileName.getBytes("UTF-8"), "ISO8859-1");//其它浏览器
File file = new File(filePath);
if (file.exists()) {
int fileLength = (int) file.length();
if (fileLength != 0) {
response.reset();
response.setContentType("application/octet-stream");
response.setHeader("Content-disposition", "attachment;filename="+fileName);
response.setContentLength(fileLength);
InputStream is = new FileInputStream(filePath);
byte[] buffer = new byte[1024];
ServletOutputStream fos = response.getOutputStream();
int len = 0;
while ((len = is.read(buffer)) != -1)
fos.write(buffer, 0, len);
is.close();
fos.flush();
fos.close();
}
}
}jsp中
<%@ page language="java" contentType="text/html; charset=UTF-8"
pageEncoding="UTF-8"%>
<%@taglib prefix="c" uri="http://java.sun.com/jsp/jstl/core" %>
<!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>File down page</title>
<script type="text/javascript">
function downfile(name) {
// alert(name);
/* var xmlhttp;
if (window.XMLHttpRequest)
xmlhttp = new XMLHttpRequest();
else
xmlhttp = new ActiveXObject("MIcrosoft.XMLHTTP");
// xmlhttp = createRequestObject();//用此方法创建xmlHttpRequest，避免浏览器兼容问题
xmlhttp.open("GET", "DownLoadFile?fileName=" + encodeURI(encodeURI(name)), true);
xmlhttp.send(); */
window.location.href="DownLoadFile?fileName=" + encodeURI(encodeURI(name));
}
</script>
</head>
<body>
<table width="100%" border="1">
<tr>
<td width="60%" align="center">文件名称</td>
<td width="40%" align="center">操作</td>
</tr>
<c:forEach items="${fileList}" var="f">
<tr>
<td>${f }</td>
<td>
<input type="button" name="downfile" value="文件下载" onclick="downfile('${f}')">
</td>
</tr>
</c:forEach>
</table>
</body>
</html>web.xml中
<?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>FileOperation</display-name> <!-- 文件下载 --> <servlet> <description></description> <display-name>DownLoadFile</display-name> <servlet-name>DownLoadFile</servlet-name> <servlet-class>com.dengsilinming.file.servlet.DownLoadFile</servlet-class> </servlet> <servlet-mapping> <servlet-name>DownLoadFile</servlet-name> <url-pattern>/DownLoadFile</url-pattern> </servlet-mapping> <welcome-file-list> <welcome-file>index.jsp</welcome-file> </welcome-file-list> </web-app>文件下载时标题的乱码问题得到了解决，在IE、FireFox、Google Chrome中都已经测试过。
项目源码可以到 这里下载，源码中还包括一个简单的文件上传功能(逻辑有点乱，没有完善)。