Java文件下载controller

在Spring MVC中，可以使用以下的Controller实现文件下载：

@Controller
public class FileDownloadController {
    private static final int BUFFER_SIZE = 4096;
    
    @RequestMapping(value = "/download", method = RequestMethod.GET)
    public void downloadFile(HttpServletRequest request, HttpServletResponse response) throws IOException {
        // 获取要下载的文件路径
        String filePath = "/path/to/file/example.pdf";
        File downloadFile = new File(filePath);
        FileInputStream inputStream = new FileInputStream(downloadFile);
        
        // 设置响应头
        response.setContentType("application/pdf");
        response.setContentLength((int) downloadFile.length());
        response.setHeader("Content-Disposition", "attachment; filename=\"" + downloadFile.getName() + "\"");
        
        // 使用缓冲流读取文件并输出到客户端
        OutputStream outputStream = response.getOutputStream();
        byte[] buffer = new byte[BUFFER_SIZE];
        int bytesRead = -1;
        while ((bytesRead = inputStream.read(buffer)) != -1) {
            outputStream.write(buffer, 0, bytesRead);
        }
        inputStream.close();
        outputStream.close();
    }
}

这个Controller会接收GET请求，将指定路径下的文件以二进制流形式输出到响应中，使得浏览器会弹出下载文件的对话框。需要注意的是，需要在Spring MVC的配置文件中配置视图解析器和Handler映射。