使用超级链接下载,一般会在浏览器中直接打开,而不是出现下载框
如果要确保出现下载框下载文件,则需要设置response中的参数:
1是要设置用附件的方式下载
Content-Disposition: attachment; filename =
2要设定内容的MIME类型
Content-Type：application/x-msdownload
下载的页面代码:
<!DOCTYPE html> <html> <head> <meta charset="UTF-8"> <title>Insert title here</title> </head> <body> <h1>服务器的文件资源 点击下载</h1> <a href="/down/download/a.flv">a.flv</a><br> <a href="/down/download/a.jpg">a.jpg</a><br> <a href="/down/download/a.mp3">a.mp3</a><br> <a href="/down/download/a.mp4">a.mp4</a><br> <a href="/down/download/a.txt">a.txt</a><br> <a href="/down/download/a.zip">a.zip</a><br> <h1>肯定下载</h1> <a href="/down/down?filename=a.jpg">美女.jpg</a><br> </body> </html>
原始servlet
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.UnsupportedEncodingException;
import java.net.URLEncoder;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import sun.misc.BASE64Encoder;
/**
* 文件下载的Servlet
*/
public class DownloadServlet extends HttpServlet {
private static final long serialVersionUID = 1L;
protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
// 1.接收参数
String filename = new String(request.getParameter("filename"));
System.out.println(filename);
// 2.完成文件下载:
// 2.1设置Content-Type头
String type = this.getServletContext().getMimeType(filename);
response.setHeader("Content-Type", type);
// 2.3设置文件的InputStream.
String realPath = this.getServletContext().getRealPath("/download/"+filename);
// 根据浏览器的类型处理中文文件的乱码问题:
String agent = request.getHeader("User-Agent");
System.out.println(agent);
if(agent.contains("Firefox")){
filename = base64EncodeFileName(filename);
}else{
filename = URLEncoder.encode(filename,"UTF-8");
}
// 2.2设置Content-Disposition头
response.setHeader("Content-Disposition", "attachment;filename="+filename);
InputStream is = new FileInputStream(realPath);
// 获得response的输出流:
OutputStream os = response.getOutputStream();
int len = 0;
byte[] b = new byte[1024];
while((len = is.read(b))!= -1){
os.write(b, 0, len);
}
is.close();
}
public static String base64EncodeFileName(String fileName) {
BASE64Encoder base64Encoder = new BASE64Encoder();
try {
return "=?UTF-8?B?"
+ new String(base64Encoder.encode(fileName
.getBytes("UTF-8"))) + "?=";
} catch (UnsupportedEncodingException e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
protected void doPost(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
doGet(request, response);
}
}
检查下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" 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>down</display-name>
<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>
<servlet>
<description></description>
<display-name>DownloadServlet</display-name>
<servlet-name>DownloadServlet</servlet-name>
<servlet-class>DownloadServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>DownloadServlet</servlet-name>
<url-pattern>/down</url-pattern>
</servlet-mapping>
</web-app>
原始上传方式要有上传按钮 提交按钮及表单才行
相比之下ocupload(即 one-click-upload 一键上传)要简单的多,只需一个按钮
一键上传的upload()方法需要ocupload的js支持 jquery.ocupload-1.1.2.js
页面上需要引入
<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-1.8.3.js"></script>
<script type="text/javascript" src="${pageContext.request.contextPath }/js/ocupload/jquery.ocupload-1.1.2.js"></script>
上传的页面代码:
<%@ 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>
<script type="text/javascript" src="${pageContext.request.contextPath }/js/jquery-1.8.3.js"></script>
<script type="text/javascript" src="${pageContext.request.contextPath }/js/ocupload/jquery.ocupload-1.1.2.js"></script>
</head>
<body>
//文件上传页面三个要素 :<br>
1、表单提交方式必须post <br>
2、设置表单属性encty="multipart/form-data" <br>
3、在表单中存在input type="file" 必须有name<br>
<iframe name="aaaa" style="display: none;"></iframe>
<form target="aaaa" action="abc.action" method="post" enctype="multipart/form-data">
<input type="file" name="upload" value="选择文件">
<input type="submit" value="上传">
</form>
<hr>
使用ocupload实现文件上传:原理调用upload方法动态修改html元素<br>
1、在页面中提供任意元素 给出Id<br>
2、在页面加载完成后调用upload方法<br>
<input type="button" id="myBtn" value="上传">
<script type="text/javascript">
$(function(){
$("#myBtn").upload({
action:‘xyz.action‘, //提交url
name:‘upload‘ //提交文件参数名
});
})
</script>
</body>
</html>
如何解决上传不用刷新问题?
使用<iframe>标签,把表单的target指向iframe,再把iframe隐藏即可
Java项目中的下载 与 上传
原文地址：https://www.cnblogs.com/qingyundian/p/9249128.html
时间： 2024-11-10 01:12:23