简介

Thumbnailator 是一个优秀的图片处理的Google开源Java类库。处理效果远比Java API的好。从API提供现有的图像文件和图像对象的类中简化了处理过程，两三行代码就能够从现有图片生成处理后的图片，且允许微调图片的生成方式，同时保持了需要写入的最低限度的代码量。还支持对一个目录的所有图片进行批量处理操作。

支持的处理操作：图片缩放、裁剪、水印添加、旋转、保持比例、格式转换等等。Thumbnailator至今仍在不断更新……

准备工作

依赖

<!-- Thumbnailator图片处理 -->
<dependency>
    <groupId>net.coobird</groupId>
    <artifactId>thumbnailator</artifactId>
    <version>0.4.8</version>
</dependency>

上传页面

<!DOCTYPE html>
<html lang="en" xmlns="http://www.w3.org/1999/html" xmlns="http://www.w3.org/1999/html">
<head>
    <meta charset="UTF-8">
    <title>图上上传处理</title>
    <script src="https://cdn.bootcdn.net/ajax/libs/jquery/3.5.1/jquery.js"></script>
</head>

<body>
<form enctype="multipart/form-data" method="post" id="upload" role="form">
    <input type="file" name="file" id="file" accept="image/jpeg,image/jpg,image/png,image/gif">
    <input type="button" id="but" value="上传图片">
</form>

</br></br>
<input type="text" style="border:none;width:500px" name="tbg" id="tbg">
</br></br>
<img src="" alt="" id="tbgShow">

</br></br>
<input type="text" style="border:none;width:500px" name="ntbg" id="ntbg">
</br></br>
<img src="" alt="" id="ntbgShow">

</br></br>
<input type="text" style="border:none;width:300px" name="ppt" id="ppt">
</br></br>
<img src="" alt="" id="pptShow">

</br></br>
<input type="text" style="border:none;width:300px" name="rt" id="rt">
</br></br>
<img src="" alt="" id="rtShow">

</br></br>
<input type="text" style="border:none;width:300px" name="cp" id="cp">
</br></br>
<img src="" alt="" id="cpShow">

</br></br>
<input type="text" style="border:none;width:300px" name="wm" id="wm">
</br></br>
<img src="" alt="" id="wmShow">

</br></br>
<input type="text" style="border:none;width:300px" name="ti" id="ti">
</br></br>
<img src="" alt="" id="tiShow">

</br></br>
<input type="text" style="border:none;width:300px" name="ci" id="ci">
</br></br>
<img src="" alt="" id="ciShow">

</br></br>
<input type="text" style="border:none;width:300px" name="os" id="os">
</br></br>
<img src="" alt="" id="osShow">

</br></br>
<input type="text" style="border:none;width:300px" name="bi" id="bi">
</br></br>
<img src="" alt="" id="biShow">

</br></br>
<input type="text" style="border:none;" name="avatar" id="avatar">
</br></br>
<img src="" alt="" id="avatarShow">

<script type="text/javascript">
    $("#but").click(function () {
            var data = new FormData($("#upload")[0]);
            if ($("#file").val() != "" && $("#file")[0].files[0].size / 1000 < 1024 * 5) { // 限制图片大小
                $.ajax({
                    async: false,
                    type: "POST",
                    url: "/process",
                    dataType: "json",
                    data: data,
                    fileElementId: "file",
                    cache: false,   // 上传文件不需要缓存
                    contentType: false, // 不设置contentType值，已经声明属性enctype="multipart/form-data"，所以这里设置为false。
                    processData: false, // data值是FormData对象，不需要对数据做处理
                    success: function (d) {
                        if (
                            d.hasOwnProperty("srcPath") || d.hasOwnProperty("tbgPath") ||
                            d.hasOwnProperty("pptPath") || d.hasOwnProperty("ntbgPath") ||
                            d.hasOwnProperty("rtPath") || d.hasOwnProperty("cpPath") ||
                            d.hasOwnProperty("wmPath") || d.hasOwnProperty("tiPath") ||
                            d.hasOwnProperty("ciPath") || d.hasOwnProperty("osPath") ||
                            d.hasOwnProperty("biPath")
                        ) {
                            //图片显示
                            $("#avatar").attr("value", d.srcMsg);
                            $("#avatarShow").attr("src", d.srcPath);

                            $("#tbg").attr("value", d.tbgMsg);
                            $("#tbgShow").attr("src", d.tbgPath);

                            $("#ntbg").attr("value", d.ntbgMsg);
                            $("#ntbgShow").attr("src", d.ntbgPath);

                            $("#ppt").attr("value", d.pptMsg);
                            $("#pptShow").attr("src", d.pptPath);

                            $("#rt").attr("value", d.rtMsg);
                            $("#rtShow").attr("src", d.rtPath);

                            $("#cp").attr("value", d.cpMsg);
                            $("#cpShow").attr("src", d.cpPath);

                            $("#wm").attr("value", d.wmMsg);
                            $("#wmShow").attr("src", d.wmPath);

                            $("#ti").attr("value", d.tiMsg);
                            $("#tiShow").attr("src", d.tiPath);

                            $("#ci").attr("value", d.ciMsg);
                            $("#ciShow").attr("src", d.ciPath);

                            $("#os").attr("value", d.osMsg);
                            $("#osShow").attr("src", d.osPath);

                            $("#bi").attr("value", d.biMsg);
                            $("#biShow").attr("src", d.biPath);
                        } else {
                            alert("上传失败");
                        }
                    },
                    error: function (e) {
                        alert("上传异常");
                    }
                });
            }
        }
    )
</script>
</body>
</html>

文件上传工具类

/**
 * @author Nicky
 * @version 1.0
 * @className FileUtils
 * @blog goitman.cn | blog.csdn.net/minkeyto
 * @description 文件上传工具类
 * @date 2021/3/10 15:47
 */
public class FileUtils {

    /**
     * @param file     文件
     * @param path     文件存放路径
     * @param fileName 保存的文件名
     * @return
     */
    public static boolean upload(MultipartFile file, String path, String fileName) {

        //确定上传的文件名
        String realPath = path + "\\" + fileName;

        File dest = new File(realPath);

        //判断文件父目录是否存在
        if (!dest.getParentFile().exists()) {
            dest.getParentFile().mkdir();
        }

        try {
            //保存文件
            file.transferTo(dest);
            return true;
        } catch (IllegalStateException e) {
            e.printStackTrace();
            return false;
        } catch (IOException e) {
            e.printStackTrace();
            return false;
        }
    }
}

请求接口

@RequestMapping("/process")
public String imagePro(MultipartFile file) throws IOException {
    Map<String, Object> map = new HashMap<>();

    String filename = null;
    String url = "http://127.0.0.1:8080/img/";
    String localPath = null;
    String srcPath = null;
    String suffixName = null;

    String type = file.getContentType();
    if (type.equals("image/jpeg") || type.equals("image/jpg") || type.equals("image/png") || type.equals("image/gif")) {
        filename = file.getOriginalFilename();
        suffixName = filename.substring(filename.lastIndexOf("."));
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        localPath = this.getClass().getResource("/").getPath() + "static/img/";
        srcPath = localPath + uuidName;

        if (FileUtils.upload(file, localPath, uuidName)) {
            map.put("srcPath", url + uuidName);
            map.put("srcMsg", "原图大小为：" + String.format("%.0f", file.getSize() / 1024f) + " KB");
        }
    }

    thumbnailImg(map, 200, 300, url, localPath, srcPath, suffixName);
    thumbnailImg2(map, 200, 300, url, localPath, srcPath, suffixName);
    proportionImg(map, 0.5, url, localPath, srcPath, suffixName);
    rotatingImg(map, 200, 300, 90, url, localPath, srcPath, suffixName);
    compressionImg(map, 1, 0.5, url, localPath, srcPath, suffixName);
    watermarkImg(map, 500, 500,"1.jpg",0.5f,0.8, url, localPath, srcPath, suffixName);
    tailoringImg(map, 300, 300, url, localPath, srcPath, suffixName);
    conversionImg(map, "gif", url, localPath, srcPath, suffixName);
    outputStream(map, "gif", url, localPath, srcPath, suffixName);
    bufferedImg(map, "bmp", url, localPath, srcPath, suffixName);
    return JSON.toJSONString(map);
}

原图

文件大小：468 KB 分辨率：2560*1440像素
2022617.jpg

功能演示

按指定大小缩放图片（遵循原图高宽比例）

/**
 * @method thumbnailImg
 * @description 按指定大小缩放图片（遵循原图高宽比例）
 * @param [map, wdith 宽度, heigth 高度, url 请求地址, localPath 本地项目地址, srcPath 原图片地址, suffixName 文件后缀名]
 * @return void
 */
private void thumbnailImg(Map<String, Object> map, int wdith, int heigth, String url, String localPath, String srcPath, String suffixName) {
    try {
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        // of()可设置为图片目录地址，toFile()可设为图片转换后的目录地址，图片批量处理
        Thumbnails.of(srcPath)
                .size(wdith, heigth)
                .toFile(localPath + uuidName);
        File file = new File(localPath + uuidName);
        BufferedImage bin = ImageIO.read(file);
        map.put("tbgPath", url + uuidName);
        map.put("tbgMsg", "遵循原图缩略大小为：" + String.format("%.0f", file.length() / 1024f) + " KB; " + "比例大小为：" + bin.getWidth() + "*" + bin.getHeight());
    } catch (IOException e) {
        e.printStackTrace();
    }
}

按指定大小缩放图片（不遵循原图比例）

/**
     * @method thumbnailImg2
     * @description 按指定大小缩放图片（不遵循原图比例）
     * @param [map, wdith, heigth, url, localPath, srcPath , suffixName]
     * @return void
     */
    private void thumbnailImg2(Map<String, Object> map, int wdith, int heigth, String url, String localPath, String srcPath, String suffixName) {
        try {
            String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
            // keepAspectRatio值为false，默认为true
            Thumbnails.of(srcPath)
                    .size(wdith, heigth)
                    .keepAspectRatio(false)
                    .toFile(localPath + uuidName);
            File file = new File(localPath + uuidName);
            // 图像缓存区类
            BufferedImage bin = ImageIO.read(file);
            map.put("ntbgPath", url + uuidName);
            map.put("ntbgMsg", "不遵循原图缩略大小为：" + String.format("%.0f", file.length() / 1024f) + " KB; " + "比例大小为：" + bin.getWidth() + "*" + bin.getHeight());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

按比例率缩放图片

/**
 * @method  proportionImg
 * @description  按比例率缩放图片
 * @param  [map, percentag 比例值, url, localPath, srcPath, suffixName]
 * @return  void
 */
private void proportionImg(Map<String, Object> map, double percentag, String url, String localPath, String srcPath, String suffixName) {
    try {
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        // scale 取值范围：大于1：放大，反之缩小；等于1：比例不变，压缩图片大小；等同于百分比)
        Thumbnails.of(srcPath)
                .scale(percentag)
                .toFile(localPath + uuidName);
        map.put("pptPath", url + uuidName);
        map.put("pptMsg", "比例图大小为：" + String.format("%.0f", new File(localPath + uuidName).length() / 1024f) + " KB; " + "比例值为：" + percentag);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

旋转图片

/**
 * @method rotatingImg
 * @description 旋转图片
 * @param [map, wdith, heigth, angle 角度, url, localPath, srcPath, suffixName]
 * @return void
 */
private void rotatingImg(Map<String, Object> map, int wdith, int heigth, int angle, String url, String localPath, String srcPath, String suffixName) {
    try {
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        // rotate角度：正数顺时针旋转，反之亦然
        Thumbnails.of(srcPath)
                .size(wdith, heigth)
                .rotate(angle)
                .toFile(localPath + uuidName);
        map.put("rtPath", url + uuidName);
        map.put("rtMsg", "旋转角度为：" + angle);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

压缩图片文件大小

比例图大小为：72 KB; 比例值为：0.5 (压缩图与原图分辨率一致，此代码未做比例缩放处理)

/**
 * @method compressionImg
 * @description 压缩图片文件大小
 * @param [map, percentag 比例值, compressValue 压缩值, url, localPath, srcPath , suffixName]
 * @return void
 */
private void compressionImg(Map<String, Object> map, double percentag, double compressValue, String url, String localPath, String srcPath, String suffixName) {
    try {
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        // outputQuality 取值范围：0.0-1.0之间，等于1质量最高，等同于百分比，文件大小变大
        Thumbnails.of(srcPath)
                .scale(percentag)
                .outputQuality(compressValue)
                .toFile(localPath + uuidName);
        map.put("cpPath", url + uuidName);
        map.put("cpMsg", "压缩图大小为：" + String.format("%.0f", new File(localPath + uuidName).length() / 1024f) + " KB; " + "压缩值为：" + compressValue);
    } catch (IOException e) {
        e.printStackTrace();
    }
}

添加水印

/**
 * @method  watermarkImg
 * @description  添加水印
 * @param  [map, wdith, heigth, fileName 图片名称, transparency 透明度, compressValue 压缩值, url, localPath, srcPath, suffixName]
 * @return  void
 */
private void watermarkImg(Map<String, Object> map, int wdith, int heigth, String fileName, float transparency, double compressValue, String url, String localPath, String srcPath, String suffixName) {
    try {
        String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
        // 读取水印图片
        BufferedImage read = ImageIO.read(new File(localPath + fileName));
        /*
         * watermark(位置，水印图，透明度)：Positions.BOTTOM_RIGHT表示在右下角，有9个位置枚举可选
         * transparency 取值范围：0.0-1.0之间，1为不透明
         */
        Thumbnails.of(srcPath)
                .size(wdith, heigth)
                .watermark(Positions.BOTTOM_RIGHT, read, transparency)
                .outputQuality(compressValue).toFile(localPath + uuidName);
        map.put("wmPath", url + uuidName);
        map.put("wmMsg", "添加水印成功");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

图片裁剪

    /**
     * @method  tailoringImg
     * @description  图片裁剪
     * @param  [map, wdith, heigth, url, localPath, srcPath, suffixName]
     * @return  void
     */
    private void tailoringImg(Map<String, Object> map, int wdith, int heigth, String url, String localPath, String srcPath, String suffixName) {
        try {
            String uuidName = UUID.randomUUID().toString().replace("-", "") + suffixName;
            /*
             * sourceRegion(位置，裁剪宽度，裁剪高度)
             * 位置：Positions.CENTER 表示在中间，有9个位置枚举可选，也可用两个像素值定位
             */
            Thumbnails.of(srcPath)
//                    .sourceRegion(Positions.CENTER, wdith, heigth)
                    .sourceRegion(0,0, wdith, heigth)
                    .size(wdith, heigth)
                    .toFile(localPath + uuidName);
            map.put("tiPath", url + uuidName);
            map.put("tiMsg", "图片裁剪成功");
        } catch (IOException e) {
            e.printStackTrace();
        }
    }

图片格式转换

/**
* @method  conversionImg
* @description 图片格式转换
* @param  [map, format 图片格式, url, localPath, srcPath, suffixName]
* @return  void
*/
private void conversionImg(Map<String, Object> map, String format, String url, String localPath, String srcPath, String suffixName) {
    try {
        String formatPath = srcPath.substring(0, srcPath.lastIndexOf(".")) + "." + format;
        String fileName = srcPath.substring(srcPath.lastIndexOf("/") + 1, srcPath.lastIndexOf(".")) + "." + format;
        // outputFormat： 支持bmp,jpg,png,gif,jpeg格式
        Thumbnails.of(srcPath)
                .scale(0.5f)
                .outputFormat(format)
                .toFile(formatPath);
        map.put("ciPath", url + fileName);
        map.put("ciMsg", "格式为：" + format + "    图片大小为：" + String.format("%.0f", new File(formatPath).length() / 1024f) + " KB; ");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

把图片输出至输出流

/**
* @method  outputStream
* @description 把图片输出至输出流
 * @param  [map, format, url, localPath, srcPath, suffixName]
* @return  void
*/
private void outputStream(Map<String, Object> map, String format, String url, String localPath, String srcPath, String suffixName) {
    try {
        String formatPath = srcPath.substring(0, srcPath.lastIndexOf(".")) + "." + format;
        String fileName = srcPath.substring(srcPath.lastIndexOf("/") + 1, srcPath.lastIndexOf(".")) + "." + format;
        OutputStream os = new FileOutputStream(formatPath);

        Thumbnails.of(srcPath).size(300, 400).outputFormat(format).toOutputStream(os);
        map.put("osPath", url + fileName);
        map.put("osMsg", "输出文件流成功");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

输出图片缓冲流

/**
* @method  bufferedImg
* @description  输出图片缓冲流
* @param  [map, format, url, localPath, srcPath, suffixName]
* @return  void
*/
private void bufferedImg(Map<String, Object> map, String format,String url, String localPath, String srcPath, String suffixName) {
    try {
        String formatPath = srcPath.substring(0, srcPath.lastIndexOf(".")) + "." + format;
        String fileName = srcPath.substring(srcPath.lastIndexOf("/") + 1, srcPath.lastIndexOf(".")) + "." + format;
        OutputStream os = new FileOutputStream(formatPath);

        BufferedImage bi = Thumbnails.of(srcPath).size(300, 400).asBufferedImage();
        ImageIO.write(bi, format, os);
        map.put("biPath", url + fileName);
        map.put("biMsg", "输出图片缓冲流成功");
    } catch (IOException e) {
        e.printStackTrace();
    }
}

注意：若png、gif格式图片中含有透明背景，使用该工具压缩处理后背景会变成黑色，这是Thumbnailator的一个bug

源码地址：https://github.com/wangdaicong/spring-boot-project/tree/master/imageProcessing-demo