yovinchen
/
Note
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity
Note/大学笔记/Java/JAVA EE/Web程序设计笔记20——第十六章：文件上传和下载.md

282 lines
8.9 KiB
Markdown
Raw Permalink Normal View History

no message
2023-08-31 11:30:31 +08:00
# 第十六章：文件上传和下载
## 1.文件上传
### 1.创建项目，导包
```java
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-web</artifactId>
<version>4.3.6.RELEASE</version>
</dependency>
<!-- https://mvnrepository.com/artifact/org.springframework/spring-webmvc -->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-webmvc</artifactId>
<version>4.3.6.RELEASE</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-io/commons-io -->
<dependency>
<groupId>commons-io</groupId>
<artifactId>commons-io</artifactId>
<version>2.5</version>
</dependency>
<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
<dependency>
<groupId>commons-fileupload</groupId>
<artifactId>commons-fileupload</artifactId>
<version>1.3.2</version>
</dependency>
<dependency>
<groupId>javax.servlet</groupId>
<artifactId>servlet-api</artifactId>
<version>2.5</version>
</dependency>
```
### 2.web.xml
```java
<servlet>
<servlet-name>springmvc</servlet-name>
<servlet-class>
org.springframework.web.servlet.DispatcherServlet
</servlet-class>
<init-param>
<param-name>contextConfigLocation</param-name>
<param-value>classpath:springmvc-config.xml</param-value>
</init-param>
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>springmvc</servlet-name>
<url-pattern>/</url-pattern>
</servlet-mapping>
```
### 3.springmvc-config.xml
```java
<!-- 定义组件扫描器，指定需要扫描的包 -->
<context:component-scan base-package="com.gzh.controller" />
<!--配置注解驱动 -->
<mvc:annotation-driven />
<!-- 定义视图解析器 -->
<bean id="viewResolver" class=
"org.springframework.web.servlet.view.InternalResourceViewResolver">
<!-- 设置前缀 -->
<property name="prefix" value="/WEB-INF/jsp/" />
<!-- 设置后缀 -->
<property name="suffix" value=".jsp" />
</bean>
<!-- 配置文件上传解析器 MultipartResolver -->
<bean id="multipartResolver" class=
"org.springframework.web.multipart.commons.CommonsMultipartResolver">
<!-- 设置请求编码格式-->
<property name="defaultEncoding" value="UTF-8" />
</bean>
```
### 4.创建fileUpload.jsp
webapp下的jsp文件可以通过url直接访问
而WEB-INF下的js文件需要控制器中的方法返回才可以访问到
```html
<head>
<meta http-equiv="Content-Type" content="text/html;charset=UTF-8"/>
<title>Title</title>
<script>
function check() {
var name=document.getElementById("name").value
var file=document.getElementById("file").value
if(name==""){
alert("填写上传人");
return false;
}
if(file.length==0 || file==""){
alert("请选择上传文件")
return false;
}
return true;
}
</script>
</head>
<body>
<form action="${pageContext.request.contextPath}/fileUpload" method="post" enctype="multipart/form-data" onsubmit="return check()">
上传人：<input type="text" id="name" name="name"/>
请选择文件：<input type="file" id="file" name="uploadfile" multiple="multiple"/>
<input type="submit" value="上传"/>
</form>
</body>
```
### 5.创建success.jsp error.jsp
```html
<body>
上传失败
</body>
```
```html
<body>
上传成功
</body>
```
no message
2023-08-31 12:43:36 +08:00
![image-20220517103654553](https://lsky.hhdxw.top/imghub/img/image-20220517103654553.png)
no message
2023-08-31 11:30:31 +08:00
### 6.创建控制器
```java
package com.gzh.controller;
/**
* 文件上传
*/
@Controller
public class FileUploadController {
/**
* 执行文件上传
*/
@RequestMapping("/fileUpload")
public String handleFormUpload(@RequestParam("name") String name,
@RequestParam("uploadfile") List<MultipartFile> uploadfile,
HttpServletRequest request) {
// 判断所上传文件是否存在
if (!uploadfile.isEmpty() && uploadfile.size() > 0) {
//循环输出上传的文件
for (MultipartFile file : uploadfile) {
// 获取上传文件的原始名称
String originalFilename = file.getOriginalFilename();
// 设置上传文件的保存地址目录
String dirPath =
request.getSession().getServletContext().getRealPath("/upload/");
File filePath = new File(dirPath);
// 如果保存文件的地址不存在，就先创建目录
if (!filePath.exists()) {
filePath.mkdirs();
}
// 使用UUID重新命名上传的文件名称(上传人_uuid_原始文件名称)
String newFilename = name + "_" + UUID.randomUUID() +
"_" + originalFilename;
try {
// 使用MultipartFile接口的方法完成文件上传到指定位置
file.transferTo(new File(dirPath + newFilename));
} catch (Exception e) {
e.printStackTrace();
return "error";
}
}
// 跳转到成功页面
return "success";
} else {
return "error";
}
}
}
```
### 7.发布项目
no message
2023-08-31 12:43:36 +08:00
![image-20220517105222969](https://lsky.hhdxw.top/imghub/img/image-20220517105222969.png)
no message
2023-08-31 11:30:31 +08:00
no message
2023-08-31 12:43:36 +08:00
![image-20220517105211357](https://lsky.hhdxw.top/imghub/img/image-20220517105211357.png)
no message
2023-08-31 11:30:31 +08:00
no message
2023-08-31 12:43:36 +08:00
![image-20220517105334825](https://lsky.hhdxw.top/imghub/img/image-20220517105334825.png)
no message
2023-08-31 11:30:31 +08:00
## 2.文件下载
### 1.创建download.jsp
```html
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>下载页面</title>
</head>
<body>
<a href="${pageContext.request.contextPath }/download?filename=1.jpg">
文件下载
</a>
<a href="${pageContext.request.contextPath }/download?filename=<%=URLEncoder.encode("壁纸.jpg", "UTF-8")%>">
中文名称文件下载
</a>
</body>
```
### 2.添加控制器
下载文件的名字会产生乱码
```java
@RequestMapping("/download")
public ResponseEntity<byte[]> fileDownload(HttpServletRequest request,String filename) throws Exception {
// 指定要下载的文件所在路径
String path = request.getSession().getServletContext().getRealPath("/upload/");
// 创建该文件对象
File file = new File(path + File.separator + filename);
// 设置响应头
HttpHeaders headers = new HttpHeaders();
// 通知浏览器以下载的方式打开文件
headers.setContentDispositionFormData("attachment", filename);
// 定义以流的形式下载返回文件数据
headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
// 使用Sring MVC框架的ResponseEntity对象封装返回下载数据
return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),
headers, HttpStatus.OK);
}
```
能保证下载的文件中文名字
```java
@RequestMapping("/download")
public ResponseEntity<byte[]> fileDownload(HttpServletRequest request,String filename) throws Exception {
// 指定要下载的文件所在路径
String path = request.getSession().getServletContext().getRealPath("/upload/");
// 创建该文件对象
File file = new File(path + File.separator + filename);
// 对文件名编码，防止中文文件乱码
filename = this.getFilename(request, filename);
// 设置响应头
HttpHeaders headers = new HttpHeaders();
// 通知浏览器以下载的方式打开文件
headers.setContentDispositionFormData("attachment", filename);
// 定义以流的形式下载返回文件数据
headers.setContentType(MediaType.APPLICATION_OCTET_STREAM);
// 使用Sring MVC框架的ResponseEntity对象封装返回下载数据
return new ResponseEntity<byte[]>(FileUtils.readFileToByteArray(file),
headers, HttpStatus.OK);
}
/**
* 根据浏览器的不同进行编码设置，返回编码后的文件名
*/
public String getFilename(HttpServletRequest request,String filename) throws Exception {
// IE不同版本User-Agent中出现的关键词
String[] IEBrowserKeyWords = {"MSIE", "Trident", "Edge"};
// 获取请求头代理信息
String userAgent = request.getHeader("User-Agent");
for (String keyWord : IEBrowserKeyWords) {
if (userAgent.contains(keyWord)) {
//IE内核浏览器，统一为UTF-8编码显示
return URLEncoder.encode(filename, "UTF-8");
}
}
//火狐等其它浏览器统一为ISO-8859-1编码显示
return new String(filename.getBytes("UTF-8"), "ISO-8859-1");
}
```
### 3.发布项目
用第一个控制器，下载的文件不是中文名称
no message
2023-08-31 12:43:36 +08:00
![image-20220517112749837](https://lsky.hhdxw.top/imghub/img/image-20220517112749837.png)
no message
2023-08-31 11:30:31 +08:00
用第二个控制器，下载的文件是中文名称
no message
2023-08-31 12:43:36 +08:00
![image-20220517113013424](https://lsky.hhdxw.top/imghub/img/image-20220517113013424.png)