java 调用 ffmpeg 指令获取视频的第 n 帧图片-兼容【linux 和 win】

1.调用

 if (StringUtil.equals(HotCacheData.os, "linux")) {
                msg = processVideo(filePath, n, targetUrl);
 } else {
                if (StringUtil.isEmpty(HotCacheData.ffmpegUrl)) {
                    throw new CustomResultException(ResultEn.FILE_LOADUP_ERROR.getCode(), "win系统ffmpeg的执行文件未找到");
                }
                msg = processVideo(HotCacheData.ffmpegUrl, filePath, n, targetUrl);
}

2.封装的方法

 private static String processVideo(String filePath, int n, String targetUrl) {
        String msg = "";
        StringBuilder commend = new StringBuilder();
        commend.append("ffmpeg ")
                .append(" -i ")
                .append(filePath)
                .append(" -ss ")
                .append(" ").append(n).append(" ")
                .append(" -f ")
                .append(" image2 ")
                .append(targetUrl);
        Process process = null;
        try {
            ProcessBuilder pb = new ProcessBuilder();
            //因为process执行命令并不是像窗口中执行shell一样，所以需要添加参数，用于执行脚本
            pb.command("sh", "-c", commend.toString());
            //processBuilder支持将inputStream与ErrorStream合并为一个Stream，即所有的输出信息都合并到inputStream中，这样做可以减少一个线程
            pb.redirectErrorStream(true);
            process = pb.start();
            //由于process机制原因会导致死锁，所以需要在waitfor方法之前，创建线程用于处理inputstream中缓冲区的数据，这也是为什么要合并inputstream和errorstream的原因，在这里可以少创建一个线程
            readInputStream(process.getInputStream());
            //返回0则表示输出正常
            int resultCode = process.waitFor();
        } catch (Exception e) {
            msg = ExcBox.getExcMsg(e);
            log.info("\n视频解析帧画面异常:");
            log.info(msg);
        } finally {
            try {
                if (null != process) {
                    process.getErrorStream().close();
                    process.getInputStream().close();
                    process.getOutputStream().close();
                }
            } catch (Exception ignored) {
            }
        }
        return msg;
    }

private static String processVideo(String ffmpegPath, String filePath, int n, String targetUrl) {
        String msg = "";
        Process process = null;
        try {
            ProcessBuilder pb = new ProcessBuilder();
            //因为process执行命令并不是像窗口中执行shell一样，所以需要添加参数，用于执行脚本
            pb.command(ffmpegPath, "-y", "-i", filePath, "-ss", n + "", "-f", "image2", targetUrl);
            //processBuilder支持将inputStream与ErrorStream合并为一个Stream，即所有的输出信息都合并到inputStream中，这样做可以减少一个线程
            pb.redirectErrorStream(true);
            process = pb.start();
            //由于process机制原因会导致死锁，所以需要在waitfor方法之前，创建线程用于处理inputstream中缓冲区的数据，这也是为什么要合并inputstream和errorstream的原因，在这里可以少创建一个线程
            readInputStream(process.getInputStream());
            //返回0则表示输出正常
            int resultCode = process.waitFor();
        } catch (Exception e) {
            msg = ExcBox.getExcMsg(e);
            log.info("\n视频解析帧画面异常:");
            log.info(msg);
        } finally {
            try {
                if (null != process) {
                    process.getErrorStream().close();
                    process.getInputStream().close();
                    process.getOutputStream().close();
                }
            } catch (Exception ignored) {
            }
        }
        return msg;
    }

 //创建线程处理输出流
    private static void readInputStream(InputStream in) {
        executor.execute(new Runnable() {
            @Override
            public void run() {
                InputStreamReader reader = null;
                try {
                    reader = new InputStreamReader(in);
                    LineNumberReader line = new LineNumberReader(reader);
                    String str = null;
                    while ((str = line.readLine()) != null) {
                        System.out.println(str);
                    }
                } catch (Exception e) {
                    e.printStackTrace();
                } finally {
                    try {
                        if (reader != null) {
                            reader.close();
                        }
                    } catch (IOException e) {
                        e.printStackTrace();
                    }
                }
            }
        });
    }