参考的工具类出自博客：/p/394f9b0357b3
我仅仅只是改了下：通过getCombinationOfhead方法返回的是 byte[] 字节数组，其它不变。（因为我要将图片上传到 FastDFS，然后通过FastDFS返回 url 链接）
public final class ImageUtil {/*** 图片的间隙*/private static final int SIDE = 6;/*** 画板尺寸*/private static final int CANVANS_W = 112;private static final int CANVANS_H = 112;/*** 尺寸1 （小）*/private static final int ONE_IMAGE_SIZE = CANVANS_H - (2 * SIDE);/*** 尺寸2 （中）*/private static final int TWO_IMAGE_SIZE = (CANVANS_H - (3 * SIDE)) / 2;/*** 尺寸3 （大）*/private static final int FIVE_IMAGE_SIZE = (CANVANS_H - (4 * SIDE)) / 3;private ImageUtil() {}/*** 生成群组头像** @param paths 图片链接* @return* @throws IOException*/public static byte[] getCombinationOfhead(List<String> paths)throws IOException {List<BufferedImage> bufferedImages = new ArrayList<BufferedImage>();int imageSize = 0;if (paths.size() <= 1) {//若为一张图片imageSize = ONE_IMAGE_SIZE;} else if (paths.size() > 1 && paths.size() < 5) {//若为2-4张图片imageSize = TWO_IMAGE_SIZE;} else {//若>=5张图片imageSize = FIVE_IMAGE_SIZE;}for (int i = 0; i < paths.size(); i++) {BufferedImage resize2 = ImageUtil.resize2(paths.get(i), imageSize, imageSize, true);bufferedImages.add(resize2);}BufferedImage outImage = new BufferedImage(CANVANS_W, CANVANS_H, BufferedImage.TYPE_INT_RGB);// 生成画布Graphics g = outImage.getGraphics();Graphics2D g2d = (Graphics2D) g;// 设置背景色g2d.setBackground(new Color(231, 231, 231));// 通过使用当前绘图表面的背景色进行填充来清除指定的矩形。g2d.clearRect(0, 0, CANVANS_W, CANVANS_H);// 开始拼凑 根据图片的数量判断该生成那种样式的组合头像目前为九种for (int i = 1; i <= bufferedImages.size(); i++) {Integer size = bufferedImages.size();switch (size) {case 1:g2d.drawImage(bufferedImages.get(i - 1), SIDE, SIDE, null);break;case 2:if (i == 1) {g2d.drawImage(bufferedImages.get(i - 1), SIDE, (CANVANS_W - imageSize) / 2, null);} else {g2d.drawImage(bufferedImages.get(i - 1), 2 * SIDE + imageSize, (CANVANS_W - imageSize) / 2, null);}break;case 3:if (i == 1) {g2d.drawImage(bufferedImages.get(i - 1), (CANVANS_W - imageSize) / 2, SIDE, null);} else {g2d.drawImage(bufferedImages.get(i - 1), (i - 1) * SIDE + (i - 2) * imageSize, imageSize + (2 * SIDE), null);}break;case 4:if (i <= 2) {g2d.drawImage(bufferedImages.get(i - 1), i * SIDE + (i - 1) * imageSize, SIDE, null);} else {g2d.drawImage(bufferedImages.get(i - 1), (i - 2) * SIDE + (i - 3) * imageSize, imageSize + 2 * SIDE, null);}break;case 5:if (i <= 2) {g2d.drawImage(bufferedImages.get(i - 1), (CANVANS_W - 2 * imageSize - SIDE) / 2 + (i - 1) * imageSize + (i - 1) * SIDE, (CANVANS_W - 2 * imageSize - SIDE) / 2, null);} else {g2d.drawImage(bufferedImages.get(i - 1), (i - 2) * SIDE + (i - 3) * imageSize, ((CANVANS_W - 2 * imageSize - SIDE) / 2) + imageSize + SIDE, null);}//break;case 6:if (i <= 3) {g2d.drawImage(bufferedImages.get(i - 1), SIDE * i + imageSize * (i - 1), (CANVANS_W - 2 * imageSize - SIDE) / 2, null);} else {g2d.drawImage(bufferedImages.get(i - 1), ((i - 3) * SIDE) + ((i - 4) * imageSize), ((CANVANS_W - 2 * imageSize - SIDE) / 2) + imageSize + SIDE, null);}break;case 7:if (i <= 1) {g2d.drawImage(bufferedImages.get(i - 1), 2 * SIDE + imageSize, SIDE, null);}if (i <= 4 && i > 1) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 1) * SIDE) + ((i - 2) * imageSize), 2 * SIDE + imageSize, null);}if (i <= 7 && i > 4) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 4) * SIDE) + ((i - 5) * imageSize), 3 * SIDE + 2 * imageSize, null);}break;case 8:if (i <= 2) {g2d.drawImage(bufferedImages.get(i - 1), (CANVANS_W - 2 * imageSize - SIDE) / 2 + (i - 1) * imageSize + (i - 1) * SIDE, SIDE, null);}if (i <= 5 && i > 2) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 2) * SIDE) + ((i - 3) * imageSize), 2 * SIDE + imageSize, null);}if (i <= 8 && i > 5) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 5) * SIDE) + ((i - 6) * imageSize), 3 * SIDE + 2 * imageSize, null);}break;case 9:if (i <= 3) {g2d.drawImage(bufferedImages.get(i - 1), (i * SIDE) + ((i - 1) * imageSize), SIDE, null);}if (i <= 6 && i > 3) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 3) * SIDE) + ((i - 4) * imageSize), 2 * SIDE + imageSize, null);}if (i <= 9 && i > 6) {g2d.drawImage(bufferedImages.get(i - 1), ((i - 6) * SIDE) + ((i - 7) * imageSize), 3 * SIDE + 2 * imageSize, null);}break;default:break;}}//将BufferedImage转为byte[]字节数组ByteArrayOutputStream baos = new ByteArrayOutputStream();ImageIO.write(outImage, "jpg", baos );baos.flush();byte[] imageInByte = baos.toByteArray();baos.close();return imageInByte;}/*** 图片缩放** @param filePath 图片路径* @param height 高度* @param width 宽度* @param bb 比例不对时是否需要补白*/public static BufferedImage resize2(String filePath, int height, int width,boolean bb) {try {double ratio = 0; // 缩放比例BufferedImage bi = null;if (filePath.indexOf("http://") == 0) {bi = ImageIO.read(new URL(filePath));} else {bi = ImageIO.read(new File(filePath));}Image itemp = bi.getScaledInstance(width, height,Image.SCALE_SMOOTH);// 计算比例if ((bi.getHeight() > height) || (bi.getWidth() > width)) {if (bi.getHeight() > bi.getWidth()) {ratio = (new Integer(height)).doubleValue() / bi.getHeight();} else {ratio = (new Integer(width)).doubleValue() / bi.getWidth();}AffineTransformOp op = new AffineTransformOp(AffineTransform.getScaleInstance(ratio, ratio), null);itemp = op.filter(bi, null);}if (bb) {BufferedImage image = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);Graphics2D g = image.createGraphics();g.setColor(Color.white);g.fillRect(0, 0, width, height);if (width == itemp.getWidth(null)) {g.drawImage(itemp, 0, (height - itemp.getHeight(null)) / 2,itemp.getWidth(null), itemp.getHeight(null),Color.white, null);} else {g.drawImage(itemp, (width - itemp.getWidth(null)) / 2, 0,itemp.getWidth(null), itemp.getHeight(null),Color.white, null);}g.dispose();itemp = image;}return (BufferedImage) itemp;} catch (IOException e) {e.printStackTrace();}return null;}}
关于FastDFS与SpringBoot的配置可以看该博文：/xyang81/article/details/52850667
使用的FastDFS版本：
<dependency><groupId>com.github.tobato</groupId><artifactId>fastdfs-client</artifactId><version>1.26.2</version></dependency>
在FastDFSClientWrapper中 新增了一个方法：（其实只是把入参变成了 byte[]）
@Componentpublic class FastDFSClientWrapper {@Autowiredprivate FastFileStorageClient storageClient;/*** 上传byte[]字节数组*/public String uploadFile(byte[] buff, String fileExtension) {ByteArrayInputStream stream = new ByteArrayInputStream(buff);StorePath storePath = storageClient.uploadFile(stream,buff.length, fileExtension,null);return getResAccessUrl(storePath);}// 封装图片URL地址private String getResAccessUrl(StorePath storePath) {return storePath.getFullPath();}}
然后就可以使用了：
@RestController@RequestMapping("/")public class GroupsController {@Autowiredprivate FastDFSClientWrapper dfsClient;/*** @param picUrls FastDFS上的图片链接集合* @return 返回图片在FastDFS上的url链接*/private String init9Pic(List<String> picUrls){try {//生成九宫格群组头像byte[] buff = ImageUtil.getCombinationOfhead(picUrls);//上传到FastDFSString url = dfsClient.uploadFile(buff,"jpg");if(!Objects.equals(url, "")){return url;}} catch (IOException e) {e.printStackTrace();}return "";}}
搞定：
