😑

.gitignore

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+/target/
+
+### IntelliJ IDEA ###
+.idea
+*.iws
+*.iml
+*.ipr
+
+.DS_Store

README.md

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+# Moment [![image](https://img.shields.io/badge/license-MIT-green.svg)](https://github.com/FantasticMao/moment/blob/master/LICENSE) [![image](https://img.shields.io/badge/release-download-blue.svg)](https://github.com/FantasticMao/moment/releases)
+
+Moment 是一个简单（可能没用）的小工具，它可以把多张图片（一般是视频截图）的底部字幕，拼接到第一张图片底下。
+
+## 在线演示
+Moment 可以用来保存视频的精彩瞬间：
+
+[![demo](doc/demo.png)](https://www.bilibili.com/video/av31172471)
+
+## 下载和使用
+Moment 下载地址：https://github.com/FantasticMao/moment/releases ，它以 Java 语言编写，以 .jar 文件发布，使用时需预先 [安装 Java 运行环境](https://www.baidu.com/s?wd=安装%20JRE)。
+
+Moment 使用手册：
+```
+java -jar moment-1.0.jar [options]
+  Options:
+    * -p, --path
+      The path of image list that need to be stitched
+    -h, --height
+      The bottom subtitle height should be in unit px
+      Default: 120
+    --out
+      The directory to save the finished image
+      Default: the current directory
+```

pom.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+
+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>cn.fantasticmao.util</groupId>
+    <artifactId>moment</artifactId>
+    <version>1.0</version>
+
+    <name>moment</name>
+    <url>https://github.com/FantasticMao/moment</url>
+
+    <properties>
+        <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
+        <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
+        <java.version>1.8</java.version>
+    </properties>
+
+    <dependencies>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>4.11</version>
+            <scope>test</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>org.projectlombok</groupId>
+            <artifactId>lombok</artifactId>
+            <version>1.18.2</version>
+            <scope>provided</scope>
+        </dependency>
+
+        <dependency>
+            <groupId>com.beust</groupId>
+            <artifactId>jcommander</artifactId>
+            <version>1.72</version>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- http://maven.apache.org/plugins/maven-assembly-plugin/ -->
+            <plugin>
+                <artifactId>maven-assembly-plugin</artifactId>
+                <version>3.1.0</version>
+                <configuration>
+                    <descriptorRefs>
+                        <descriptorRef>jar-with-dependencies</descriptorRef>
+                    </descriptorRefs>
+
+                    <archive>
+                        <manifest>
+                            <mainClass>cn.fantasticmao.util.moment.Main</mainClass>
+                        </manifest>
+                    </archive>
+                </configuration>
+                <executions>
+                    <execution>
+                        <id>make-assembly</id>
+                        <phase>package</phase>
+                        <goals>
+                            <goal>single</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

src/main/java/cn/fantasticmao/util/moment/Args.java

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+package cn.fantasticmao.util.moment;
+
+import com.beust.jcommander.Parameter;
+import lombok.Data;
+
+import java.io.File;
+import java.util.List;
+
+/**
+ * Args 命令行输入参数
+ *
+ * @author maodh
+ * @since 2018/9/4
+ */
+@Data
+class Args {
+    @Parameter(names = {"-p", "--path"}, description = "The path of image list that need to be stitched", required = true, order = 0)
+    private List<String> pathList;
+    @Parameter(names = {"-h", "--height"}, description = "The bottom subtitle height should be in unit px", order = 1)
+    private Integer height = 120;
+    @Parameter(names = "--out", description = "The directory to save the finished image", order = 2)
+    private String outputDir = System.getProperty("user.dir") + File.separator;
+}

src/main/java/cn/fantasticmao/util/moment/FileUtil.java

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+package cn.fantasticmao.util.moment;
+
+import java.io.File;
+import java.io.FileInputStream;
+import java.io.IOException;
+
+/**
+ * FileUtil
+ *
+ * @author maodh
+ * @since 2018/9/4
+ */
+class FileUtil {
+
+    // common file utils
+
+    static String getFileNameWithoutExtension(File file) {
+        String fileName = file.getName();
+        int lastIndexOf = fileName.lastIndexOf(".");
+        return lastIndexOf == -1 ? "" : fileName.substring(0, lastIndexOf);
+    }
+
+    static String getFileExtension(File file) {
+        String fileName = file.getName();
+        int lastIndexOf = fileName.lastIndexOf(".");
+        return lastIndexOf == -1 ? "" : fileName.substring(lastIndexOf);
+    }
+
+    static String getFileExtensionWithoutDot(File file) {
+        String fileName = file.getName();
+        int lastIndexOf = fileName.lastIndexOf(".");
+        return lastIndexOf == -1 ? "" : fileName.substring(lastIndexOf + 1);
+    }
+
+    // image file utils
+
+    /**
+     * 比较图片的后缀名和魔数是否相符
+     *
+     * @see cn.fantasticmao.util.moment.ImageType
+     */
+    static boolean compareImageExtensionAndMagicNumber(File image) {
+        // 图片的后缀名
+        final String imageExtension = FileUtil.getFileExtension(image);
+        // 图片的类型
+        final ImageType imageType = ImageType.ofExtension(imageExtension);
+        // 图片的魔数
+        final String imageMagicNumber = FileUtil.getImageMagicNumber(image);
+        return imageType != null && imageMagicNumber.startsWith(imageType.magicNumber);
+    }
+
+    private static String getImageMagicNumber(File file) {
+        final int byteSize = 1 << 2;
+        byte[] bytes = new byte[byteSize];
+        try (FileInputStream in = new FileInputStream(file)) {
+            in.read(bytes, 0, byteSize);
+            return bytesToHex(bytes);
+        } catch (IOException e) {
+            e.printStackTrace();
+            return "";
+        }
+    }
+
+    private static final char[] HEX_ARRAY = "0123456789ABCDEF".toCharArray();
+
+    private static String bytesToHex(byte[] bytes) {
+        char[] hexChars = new char[bytes.length * 2];
+        for (int j = 0; j < bytes.length; j++) {
+            int v = bytes[j] & 0xFF;
+            hexChars[j * 2] = HEX_ARRAY[v >>> 4];
+            hexChars[j * 2 + 1] = HEX_ARRAY[v & 0x0F];
+        }
+        return new String(hexChars);
+    }
+}

src/main/java/cn/fantasticmao/util/moment/ImageType.java

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+package cn.fantasticmao.util.moment;
+
+import java.util.stream.Stream;
+
+/**
+ * ImageType
+ *
+ * @author maodh
+ * @since 2018/9/5
+ */
+enum ImageType {
+    BMP(".bmp", "424D"),
+    JPG(".jpg", "FFD8FFDB"),
+    JPEG(".jpeg", "FFD8FF"),
+    PNG(".png", "89504E47");
+
+    public final String extension;
+    public final String magicNumber;
+
+    ImageType(String extension, String magicNumber) {
+        this.extension = extension;
+        this.magicNumber = magicNumber;
+    }
+
+    public static ImageType ofExtension(final String extension) {
+        return Stream.of(ImageType.values())
+                .filter(fileType -> extension.equals(fileType.extension))
+                .findFirst().orElse(null);
+    }
+}

src/main/java/cn/fantasticmao/util/moment/Main.java

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+package cn.fantasticmao.util.moment;
+
+import com.beust.jcommander.JCommander;
+import com.beust.jcommander.ParameterException;
+
+import java.io.File;
+import java.util.List;
+import java.util.stream.Collectors;
+
+/**
+ * Main
+ *
+ * @author maodh
+ * @since 2018/9/4
+ */
+public class Main {
+
+    public static void main(String[] args) {
+        Args arguments = new Args();
+        try {
+            JCommander jCommander = JCommander.newBuilder().addObject(arguments).build();
+            jCommander.parse(args);
+        } catch (ParameterException e) {
+            e.usage();
+            return;
+        }
+
+        final List<File> imageFileList = arguments.getPathList().stream().map(File::new).collect(Collectors.toList());
+        final int subtitleHeight = arguments.getHeight();
+        final String outputDir = arguments.getOutputDir();
+
+        try {
+            File finalImageFile = StitchUtil.stitchImageList(imageFileList, subtitleHeight, outputDir);
+            System.out.println("well done, you can find your image here [ " + finalImageFile.getPath() + " ]");
+        } catch (IllegalArgumentException e) {
+            System.out.println("failed, illegal argument error suggestion: [ " + e.getMessage() + " ]");
+        } catch (Exception e) {
+            System.out.println("failed, report the problem mailto:maomao8017@gmail.com");
+            e.printStackTrace();
+        }
+    }
+}

src/main/java/cn/fantasticmao/util/moment/StitchUtil.java

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+package cn.fantasticmao.util.moment;
+
+import javax.imageio.ImageIO;
+import java.awt.image.BufferedImage;
+import java.io.File;
+import java.io.IOException;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * StitchUtil
+ *
+ * @author maodh
+ * @since 2018/9/4
+ */
+class StitchUtil {
+
+    /**
+     * @param imageFileList  图片文件列表
+     * @param subtitleHeight 字幕高度，单位 px
+     * @param outputDir      保存最终图片文件的目录
+     * @return 拼接而成的最终图片文件
+     * @throws IOException I/O Exception
+     */
+    static File stitchImageList(List<File> imageFileList, final int subtitleHeight, final String outputDir) throws IOException {
+        // 校验参数
+        if (imageFileList == null || imageFileList.size() == 0) {
+            throw new IllegalArgumentException("the image list should not be empty");
+        } else {
+            if (imageFileList.stream().anyMatch(file -> !file.exists())) {
+                throw new IllegalArgumentException("every list should be filled with image");
+            }
+        }
+        if (subtitleHeight <= 0) {
+            throw new IllegalArgumentException("the subtitle height should be a positive integer");
+        }
+        if (outputDir == null || outputDir.length() == 0) {
+            throw new IllegalArgumentException("the output directory path should not be empty");
+        } else {
+            File outputFile = new File(outputDir);
+            if (!outputFile.exists() || !outputFile.isDirectory()) {
+                throw new IllegalArgumentException("there must be an output directory for finished image");
+            }
+        }
+
+        final File firstImageFile = imageFileList.get(0);
+        // 校验第一张图片文件的后缀名和魔数
+        if (!FileUtil.compareImageExtensionAndMagicNumber(firstImageFile)) {
+            throw new IllegalArgumentException("the format of No.1 image is not supported or cannot opened");
+        }
+
+        // 第一张图片的后缀名
+        final String firstImageFileExtensionWithoutDot = FileUtil.getFileExtensionWithoutDot(firstImageFile);
+
+        // 最终拼接而成的图片
+        BufferedImage firstImage = ImageIO.read(firstImageFile);
+        final int finalImageWidth = firstImage.getWidth();
+        final int finalImageHeight = firstImage.getHeight() + (imageFileList.size() - 1) * subtitleHeight;
+        final int finalImageType = firstImage.getType();
+        BufferedImage finalImage = new BufferedImage(finalImageWidth, finalImageHeight, finalImageType);
+
+        // 拼接图片
+        finalImage.createGraphics().drawImage(firstImage, 0, 0, null);
+        for (int i = 0; i < imageFileList.size(); i++) {
+            if (i == 0) continue;
+            File thisImageFile = imageFileList.get(i);
+
+            // 校验当前图片文件的后缀名和魔数
+            if (!FileUtil.compareImageExtensionAndMagicNumber(thisImageFile)) {
+                throw new IllegalArgumentException("the format of No." + (i + 1) + " image is not supported or cannot opened");
+            }
+
+            // 校验当前图片文件的后缀名
+            final String thisImageFileExtensionWithoutDot = FileUtil.getFileExtensionWithoutDot(thisImageFile);
+            if (!Objects.equals(thisImageFileExtensionWithoutDot, firstImageFileExtensionWithoutDot)) {
+                throw new IllegalArgumentException("the extension of the No." + (i + 1) + " image should be same as the first image");
+            }
+
+            BufferedImage thisImage = ImageIO.read(thisImageFile);
+
+            // 校验当前图片的宽度
+            if (thisImage.getWidth() != firstImage.getWidth()) {
+                throw new IllegalArgumentException("the width of the No." + (i + 1) + " image should be same as the first image");
+            }
+
+            // 裁剪图片字幕
+            BufferedImage subtitle = thisImage.getSubimage(0, thisImage.getHeight() - subtitleHeight, thisImage.getWidth(), subtitleHeight);
+
+            // 拼接图片字幕
+            finalImage.createGraphics().drawImage(subtitle, 0, firstImage.getHeight() + (i - 1) * subtitleHeight, null);
+        }
+
+        // 如果最终图片文件已存在，则会覆盖
+        File finalImageFile = newFinalImageFileFromImageList(imageFileList, outputDir);
+        ImageIO.write(finalImage, firstImageFileExtensionWithoutDot, finalImageFile);
+        return finalImageFile;
+    }
+
+    private static File newFinalImageFileFromImageList(List<File> imageFileList, String outputDir) {
+        final File firstImageFile = imageFileList.get(0);
+        final String finalImageFileNameWithoutExtension = FileUtil.getFileNameWithoutExtension(firstImageFile);
+        final String finalImageFileExtension = FileUtil.getFileExtension(firstImageFile);
+
+        final String finalImagePath = outputDir + finalImageFileNameWithoutExtension + "_final" + finalImageFileExtension;
+        return new File(finalImagePath);
+    }
+
+}