视频下载增加水印说明文档

package nexus.io.kit.handler;

import java.io.File;
import java.io.IOException;
import java.io.RandomAccessFile;

import nexus.io.media.utils.VideoWaterUtils;
import nexus.io.tio.boot.http.TioRequestContext;
import nexus.io.tio.http.common.HttpRequest;
import nexus.io.tio.http.common.HttpResponse;
import nexus.io.tio.http.server.util.CORSUtils;
import nexus.io.tio.http.server.util.Resps;
import nexus.io.tio.utils.crypto.Md5Utils;
import nexus.io.tio.utils.http.ContentTypeUtils;
import nexus.io.tio.utils.hutool.FilenameUtils;
import nexus.io.tio.utils.hutool.StrUtil;

public class VideoWaterHandler {

  public HttpResponse index(HttpRequest request) {
    HttpResponse response = TioRequestContext.getResponse();
    CORSUtils.enableCORS(response);
    String path = request.getString("path");
    String text = request.getString("text");
    String filename = request.getString("filename");
    if (StrUtil.isNotBlank(filename)) {
      filename += ".mp4";
    } else {
      filename = "main.mp4";
    }
    Integer fontSize = request.getInt("font_size");
    if (fontSize == null) {
      fontSize = 24;
    }

    if (StrUtil.isBlank(path)) {
      return response.body("path can not be empty");
    }

    String targetFile = "." + path;
    File file = new File(targetFile);
    if (!file.exists()) {
      response.setStatus(404);
      return response;
    }

    String suffix = FilenameUtils.getSuffix(path);
    String contentType = ContentTypeUtils.getContentType(suffix);

    if (StrUtil.isNotBlank(text)) {
      String md5 = Md5Utils.md5Hex(text);
      String subPath = FilenameUtils.getSubPath(targetFile);
      String baseName = FilenameUtils.getBaseName(targetFile);
      String outputFile = subPath + File.separator + baseName + "_" + fontSize + "_" + md5 + "." + suffix;
      file = new File(outputFile);
      if (!file.exists()) {
        try {
          VideoWaterUtils.addWatermark(targetFile, outputFile, fontSize, text);
          targetFile = outputFile;
        } catch (IOException e) {
          e.printStackTrace();
          return response.body(e.getMessage());
        } catch (InterruptedException e) {
          e.printStackTrace();
          return response.body(e.getMessage());
        }
      }
    }

    long fileLength = file.length();
    // 检查是否存在 Range 头信息
    String range = request.getHeader("range");
    if (range != null && range.startsWith("bytes=")) {
      String rangeValue = range.substring("bytes=".length());
      String[] parts = rangeValue.split("-");
      try {
        long start = parts[0].isEmpty() ? 0 : Long.parseLong(parts[0]);
        long end = (parts.length > 1 && !parts[1].isEmpty()) ? Long.parseLong(parts[1]) : fileLength - 1;
        if (start > end || end >= fileLength) {
          response.setStatus(416);
          return response;
        }
        long contentLength = end - start + 1;
        byte[] data = new byte[(int) contentLength];

        try (RandomAccessFile raf = new RandomAccessFile(file, "r")) {
          raf.seek(start);
          raf.readFully(data);
        }
        // 设置响应头
        response.setStatus(206); // Partial Content
        response.setHeader("Content-Range", "bytes " + start + "-" + end + "/" + fileLength);
        response.setHeader("Accept-Ranges", "bytes");
        // 如果传入了 filename，则在响应头中指定下载文件名
        if (StrUtil.isNotBlank(filename)) {
          response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
        }
        Resps.bytesWithContentType(response, data, contentType);
      } catch (Exception e) {
        response.setStatus(416);
      }
    } else {
      response.setHeader("Accept-Ranges", "bytes");
      if (StrUtil.isNotBlank(filename)) {
        response.setHeader("Content-Disposition", "attachment; filename=\"" + filename + "\"");
      }
      response.setFileBody(file); 
    }
    // 视频文件（如 mp4）本身已经是压缩格式，再进行 gzip 压缩可能会破坏文件格式，导致浏览器无法正确解码。
    response.setSkipGzipped(true);
    return response;
  }
}

package nexus.io.media.utils;

import java.io.File;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class VideoWaterUtils {

  /**
   * 使用 ffmpeg 给视频添加右下角水印，并将标准输出和错误输出分别写入日志文件。
   *
   * @param inputFile     输入视频文件路径
   * @param outputFile    输出视频文件路径
   * @param fontSize      水印文字的字号
   * @param watermarkText 水印文本
   * @throws IOException          当执行命令时发生 I/O 错误
   * @throws InterruptedException 当线程等待 ffmpeg 进程结束时被中断
   */
  public static int addWatermark(String inputFile, String outputFile, int fontSize, String watermarkText) throws IOException, InterruptedException {

    String osName = System.getProperty("os.name").toLowerCase();
    String fontFile;
    if (osName.contains("win")) {
      fontFile = "C\\:/Windows/Fonts/simhei.ttf";
    } else if (osName.contains("mac")) {
      fontFile = "/Library/Fonts/Arial Unicode.ttf";
    } else if (osName.contains("nix") || osName.contains("nux") || osName.contains("aix")) {
      fontFile = "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc";
    } else {
      fontFile = "/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc";
    }

    // 构造 drawtext 过滤器参数
    // x=w-tw-10:y=h-th-10 表示让水印距离右下角各留10像素
    String template = "drawtext=fontfile='%s':text='%s':x=w-tw-10:y=h-th-10:fontsize=%d:fontcolor=yellow";
    String filterSpec = String.format(template, fontFile, watermarkText, fontSize);

    // 构造 ffmpeg 命令参数列表
    List<String> command = new ArrayList<>();
    command.add("ffmpeg");
    command.add("-i");
    command.add(inputFile);
    command.add("-vf");
    command.add(filterSpec);
    command.add("-codec:a");
    command.add("copy");
    command.add(outputFile);

    System.out.println("cmd：" + String.join(" ", command));

    ProcessBuilder pb = new ProcessBuilder(command);

    // 设置将标准输出和错误输出分别重定向到文件
    File stdoutFile = new File("ffmpeg_stdout.log");
    File stderrFile = new File("ffmpeg_stderr.log");
    pb.redirectOutput(ProcessBuilder.Redirect.to(stdoutFile));
    pb.redirectError(ProcessBuilder.Redirect.to(stderrFile));

    // 启动进程并等待完成
    Process process = pb.start();
    return process.waitFor();
  }
}