文件下载

使用ResponseEntity实现下载文件的功能

<mvc:view-controller path="/file" view-name="file"></mvc:view-controller>

<!DOCTYPE html>
<html lang="en" xmlns:th="http://www.thymeleaf.org">
<head>
    <meta charset="UTF-8">
    <title>测试文件上传和下载</title>
</head>
<body>
<a th:href="@{/testDownload}">下载1.jpg</a>
</body>
</html>

@Controller
public class FileUpAndDownController {
    @RequestMapping("/testDownload")
    public ResponseEntity<byte[]> testResponseEntity(HttpSession session) throws IOException {
        //获取整个工程对象
        ServletContext servletContext = session.getServletContext();
        //获取服务器中文件的真实路径
        String realPath = servletContext.getRealPath("/static/img/1.jpg");
        FileInputStream fileInputStream = new FileInputStream(realPath);
        //获取流中的所以字节数并创建字节数组
        byte[] bytes = new byte[fileInputStream.available()];
        //流读到字节数组中
        fileInputStream.read(bytes);
        //创建HttpHeaders
        MultiValueMap<String, String> headers = new HttpHeaders();
        //设置要下载方式以及下载文件的名字（默认文件名），只有文件名能改
        headers.add("Content-Disposition", "attachment;filename=1.jpg");
        //设置响应状态码
        HttpStatus statusCode = HttpStatus.OK;
        ResponseEntity<byte[]> responseEntity = new ResponseEntity<>(bytes, headers, statusCode);
        fileInputStream.close();
        return responseEntity;
    }
}

文件上传

文件上传要求form表单的请求方式必须为post，并且添加属性enctype=”multipart/form-data”
SpringMVC中将上传的文件封装到MultipartFile对象中，通过此对象可以获取文件相关信息
上传步骤：
a>添加依赖：

<!-- https://mvnrepository.com/artifact/commons-fileupload/commons-fileupload -->
<dependency>
    <groupId>commons-fileupload</groupId>
    <artifactId>commons-fileupload</artifactId>
    <version>1.3.1</version>
</dependency>

b>在SpringMVC的配置文件中添加配置：

<!--必须通过文件解析器的解析才能将文件转换为MultipartFile对象-->
<bean id="multipartResolver" class="org.springframework.web.multipart.commons.CommonsMultipartResolver"></bean>

c>控制器方法：

@RequestMapping("/testUp")
public String testUp(MultipartFile photo, HttpSession session) throws IOException {
    //获取上传的文件的文件名
    String fileName = photo.getOriginalFilename();
    //处理文件重名问题
    String hzName = fileName.substring(fileName.lastIndexOf("."));
    fileName = UUID.randomUUID().toString() + hzName;
    //获取服务器中photo目录的路径
    ServletContext servletContext = session.getServletContext();
    String photoPath = servletContext.getRealPath("photo");
    File file = new File(photoPath);
    if(!file.exists()){
        file.mkdir();
    }
    String finalPath = photoPath + File.separator + fileName;
    //实现上传功能
    photo.transferTo(new File(finalPath));
    return "success";
}

d>视图：

<form th:action="@{/testUp}" method="post" enctype="multipart/form-data">
    头像: <input type="file" name="photo"><br>
    <input type="submit" value="上传"><br>
</form>

文件的上传下载

文件下载

文件上传