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