ResourceHttpRequestHandler 实现视频流

Question

springboot返回视频流

package com.dplyer.demos.utils;
import org.springframework.core.io.FileSystemResource;
import org.springframework.core.io.Resource;
import org.springframework.stereotype.Component;
import org.springframework.web.servlet.resource.ResourceHttpRequestHandler;
import javax.servlet.http.HttpServletRequest;
import java.nio.file.Path;
//返回视频流
@Component
public class NonStaticResourceHttpRequestHandler extends ResourceHttpRequestHandler {
    public final static String ATTR_FILE = "NON-STATIC-FILE";

    @Override
    protected Resource getResource(HttpServletRequest request) {
        final Path filePath = (Path) request.getAttribute(ATTR_FILE);
        return new FileSystemResource(filePath);
    }

}

@RestController
@RequestMapping("/abc")
@AllArgsConstructor
public class DplayerController {

    //引入返回视频流的组件
    private final NonStaticResourceHttpRequestHandler nonStaticResourceHttpRequestHandler;
    @GetMapping("/d")
    public void videoPreview(HttpServletRequest request, HttpServletResponse response) throws Exception {

        //从视频信息中单独把视频路径信息拿出来保存
        String videoPathUrl="src/main/resources/static/my.mp4";

        //保存视频磁盘路径
        Path filePath = Paths.get(videoPathUrl);
        //Files.exists：用来测试路径文件是否存在
        if (Files.exists(filePath)) {
            //获取视频的类型，比如是MP4这样
            String mimeType = Files.probeContentType(filePath);
            if (StringUtils.hasText(mimeType)) {
                //判断类型，根据不同的类型文件来处理对应的数据
                response.setContentType(mimeType);
            }
            //转换视频流部分
            request.setAttribute(NonStaticResourceHttpRequestHandler.ATTR_FILE, filePath);
            nonStaticResourceHttpRequestHandler.handleRequest(request, response);
        } else {
            response.setStatus(HttpServletResponse.SC_NOT_FOUND);
            response.setCharacterEncoding(StandardCharsets.UTF_8.toString());
        }
    }
}

ResourceHttpRequestHandler 的作用是什么，是如何实现向前端返回视频流？

Answer 1

NonStaticResourceHttpRequestHandler 继承了 ResourceHttpRequestHandler，
将文件路径 filePath 存储在请求的属性中（使用 request.setAttribute），这样 NonStaticResourceHttpRequestHandler 就可以使用这个路径来返回资源。
最后，调用 nonStaticResourceHttpRequestHandler.handleRequest 方法，将资源作为响应返回给客户端。