Servlet实现文件的上传与下载
作者:敲代码的蒲公英 时间:2023-08-08 06:13:43
前言:
文件的上传和下载在日常开发中很是常见,那么这一功能是如何实现的呢,下面我给大家介绍一下
实现条件:
1、需要一个form标签,method为post请求
2、form的encType属性值为multipart/form-data
3、input标签的type=file
4.需要的jar包()
工程目录:
具体实现:
UploadServlet.java(上传)
import org.apache.commons.fileupload.FileItem;
import org.apache.commons.fileupload.FileItemFactory;
import org.apache.commons.fileupload.FileUpload;
import org.apache.commons.fileupload.FileUploadException;
import org.apache.commons.fileupload.disk.DiskFileItemFactory;
import javax.servlet.ServletException;
import javax.servlet.ServletInputStream;
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.List;
public class UploadServlet extends HttpServlet {
@Override
protected void doPost(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.判断上传的数据是否是多段数据(只有事多段的数据才是文件上传的)
if(FileUpload.isMultipartContent(req)){
//创建FileItemFactory工厂实现类
FileItemFactory fileItemFactory=new DiskFileItemFactory();
//创建用于解析上传数据的工具类FileUpload
FileUpload fileUpload=new FileUpload(fileItemFactory);
try {
List<FileItem> list=fileUpload.parseRequest(req);
//循环判断每一个表单项是普通类型还是上传的文件
for(FileItem fileItem:list){
if(fileItem.isFormField()){
//普通表单项
System.out.println("表单项的name属性值:"+fileItem.getFieldName());
//参数UTF-8解决乱码问题
System.out.println("表单项的value值:"+fileItem.getString("UTF-8"));
}else{
//上传的文件
System.out.println("表单项的name属性值:"+fileItem.getFieldName());
System.out.println("上传的文件名:"+fileItem.getName());
fileItem.write(new File("D:\\"+fileItem.getName()));
}
}
} catch (Exception e) {
e.printStackTrace();
}
}
}
}
download.java(下载)
import org.apache.commons.io.IOUtils;
import javax.servlet.ServletContext;
import javax.servlet.ServletException;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import java.net.URLEncoder;
public class download extends HttpServlet {
@Override
protected void doGet(HttpServletRequest req, HttpServletResponse resp) throws ServletException, IOException {
//1.获取要下载的文件名
String downloadfilename="1.jpg";
//2.读取下载的文件内容(通过ServletContext对象可以读取)
ServletContext servletContext=getServletContext();
//获取要下载的文件类型
String mimetype=servletContext.getMimeType("/file/"+downloadfilename);
//4.回传前告诉客户端回传的类型
resp.setContentType("mimetype");
//5.告诉客户端收到的数据是用来下载的(响应头)
//Content-Disposition 响应头表示收到的数据怎么处理
//attachment表示附件,表示下载
resp.setHeader("Content-Disposition","attachment;filename="+downloadfilename);
//url编码解决下载文件名乱码问题(谷歌和IE)
// resp.setHeader("Content-Disposition","attachment;filename="+ URLEncoder.encode("中国.jpg","UTF-8"));
InputStream resourceAsStream= servletContext.getResourceAsStream("/file/"+downloadfilename);
//获取响应的输出流
OutputStream outputStream=resp.getOutputStream();
//3,把下载的文件传回给客户端
//读取输入流的数据复制给输出流,输出给客户端
IOUtils.copy(resourceAsStream,outputStream);
}
}
前端页面
<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Title</title>
</head>
<body>
<form action="http://localhost:8080/upandload_war_exploded/uploadServlet" method="post" enctype="multipart/form-data" >
用户名:<input type="text" name="username"><br>
头像:<input type="file" name="photo"><br>
<input type="submit" value="上传">
</form>
</body>
</html>
成果展示:
文件的上传
服务器接受上传的文件
下载文件
来源:https://blog.csdn.net/m0_46495243/article/details/115053937
标签:Servlet,上传,下载
![](/images/zang.png)
![](/images/jiucuo.png)
猜你喜欢
一文详解C# Chart控件
2023-01-20 03:50:04
![](https://img.aspxhome.com/file/2023/6/122766_0s.png)
Unity 按钮添加OnClick事件操作
2023-06-28 15:57:27
![](https://img.aspxhome.com/file/2023/3/113683_0s.jpg)
Java 开启多线程常见的4种方法
2023-11-23 02:30:10
![](https://img.aspxhome.com/file/2023/0/58580_0s.png)
Java class文件格式之数据类型(二)_动力节点Java学院整理
2022-06-26 02:15:45
![](https://img.aspxhome.com/file/2023/3/101943_0s.jpg)
Springboot-dubbo-fescar 阿里分布式事务的实现方法
2022-05-05 05:43:16
使用Springboot 打jar包实现分离依赖lib和配置
2023-01-29 18:35:29
![](https://img.aspxhome.com/file/2023/7/76537_0s.png)
ImportBeanDefinitionRegistrar手动控制BeanDefinition创建注册详解
2021-11-11 18:49:18
SpringBoot配置Email发送功能实例
2022-03-07 20:52:20
![](https://img.aspxhome.com/file/2023/3/61943_0s.jpg)
Java8 如何移除两个相同的List对象
2023-06-07 20:57:50
![](https://img.aspxhome.com/file/2023/9/122259_0s.png)
C# 静态构造函数使用总结
2022-04-28 16:27:35
![](https://img.aspxhome.com/file/2023/5/129635_0s.jpg)
基于C#实现端口扫描器(单线程和多线程)
2021-10-16 20:32:23
![](https://img.aspxhome.com/file/2023/4/94544_0s.jpg)
JAVA设计模式之责任链模式详解
2023-10-28 21:54:47
![](https://img.aspxhome.com/file/2023/1/108461_0s.png)
Android table布局开发实现简单计算器
2021-07-15 13:05:28
![](https://img.aspxhome.com/file/2023/6/137476_0s.jpg)
C#异常执行重试的实现方法
2023-12-04 16:24:59
PC蓝牙通信C#代码实现
2023-07-06 19:59:32
Spring Boot2发布调用REST服务实现方法
2023-12-10 20:03:49
![](https://img.aspxhome.com/file/2023/1/71141_0s.png)
Java框架之Maven SSM集合
2022-04-05 16:22:54
![](https://img.aspxhome.com/file/2023/8/77988_0s.png)
Android实现动态高斯模糊效果
2021-07-02 16:56:09
![](https://img.aspxhome.com/file/2023/5/138155_0s.png)
java 查找字符串所在的位置代码
2023-12-22 21:48:17
![](https://img.aspxhome.com/file/2023/0/79820_0s.jpg)
Java 8 Stream 的终极技巧——Collectors 功能与操作方法详解
2023-02-01 16:23:30