利用Java实现了任意两张图片的垂直方向拼接，不限制大小类型，可直接用于生产。

实现任意两张图片的垂直方向拼接，对于过小图片实现了放大，保证了图片拼接后的清晰度。

对于高度大于宽度的图片，进行了-90度旋转。

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.Arrays;
import java.util.List;//垂直方向合并图片
public class ImageMerge {/*** 1比较2张图片的大小，以2张图片的最大边长为宽，以第二边长为高，构造2张空图片* 2选择第一张图片，若宽小于于高，旋转-90度，粘贴到第一张空图片上* 3选择第二张图片，若宽小于于高，旋转-90度，粘贴到第二张空图片上** @param img1 待合并的第一张图* @param img2 带合并的第二张图* @return 返回合并后的BufferedImage对象* @throws IOException*/public static BufferedImage mergeImage(BufferedImage img1, BufferedImage img2) throws IOException {//判断是否需要放大图片if (Math.max(img1.getWidth(), img1.getHeight()) > Math.max(img2.getWidth(), img2.getHeight())) {img2 = judgeIfNeedChangeImageSize(img1, img2);} else {img1 = judgeIfNeedChangeImageSize(img1, img2);}//获取背景图片宽高int w1 = img1.getWidth();int h1 = img1.getHeight();int w2 = img2.getWidth();int h2 = img2.getHeight();List<Integer> list = Arrays.asList(w1, w2, h1, h2);list.sort((v1, v2) -> v2 - v1);int maxWidth = list.get(0);int maxHeight = list.get(1);int[] backgroundImage = new int[maxWidth * maxHeight];//设置背景图片数据for (int i = 0; i < backgroundImage.length; i++) {backgroundImage[i] = -1;}//绘制背景图片BufferedImage createImage = new BufferedImage(maxWidth, maxHeight << 1, BufferedImage.TYPE_INT_RGB);createImage.setRGB(0, 0, maxWidth, maxHeight, backgroundImage, 0, maxWidth);createImage.setRGB(0, maxHeight, maxWidth, maxHeight, backgroundImage, 0, maxWidth);//准备图片一绘制数据int[] imageArrayOne = new int[w1 * h1];imageArrayOne = img1.getRGB(0, 0, w1, h1, imageArrayOne, 0, w1);if (w1 < h1) {rotateImage(w1, h1, imageArrayOne);int temp = w1;w1 = h1;h1 = temp;}//计算绘图位置，尽量居中int startX;int startY;startX = (maxWidth - w1) >> 1;startY = (maxHeight - h1) >> 1;//在背景图片上绘制图片createImage.setRGB(startX, startY, w1, h1, imageArrayOne, 0, w1);//准备图片一绘制数据int[] imageArrayTwo = new int[w2 * h2];imageArrayTwo = img2.getRGB(0, 0, w2, h2, imageArrayTwo, 0, w2);if (w2 < h2) {rotateImage(w2, h2, imageArrayTwo);int temp = w2;w2 = h2;h2 = temp;}//计算绘图位置，尽量居中startX = (maxWidth - w2) >> 1;startY = (maxHeight - h2) >> 1;//准备图片二绘制数据createImage.setRGB(startX, maxHeight + startY, w2, h2, imageArrayTwo, 0, w2);return createImage;}private static BufferedImage judgeIfNeedChangeImageSize(BufferedImage img1, BufferedImage img2) {int w1 = img1.getWidth();int h1 = img1.getHeight();int w2 = img2.getWidth();int h2 = img2.getHeight();int max1 = Math.max(w1, h1);int max2 = Math.max(w2, h2);if (max1 < max2) {return enlargementImage(img1, w1, h1, max1, max2);} else {return enlargementImage(img2, w2, h2, max2, max1);}}private static BufferedImage enlargementImage(BufferedImage srcImg, int w1, int h1, int max1, int max2) {while (max2 / max1 >= 2) {max1 *= 2;w1 *= 2;h1 *= 2;}// 放大边长BufferedImage resultImg = new BufferedImage(w1, h1, BufferedImage.TYPE_INT_RGB);//绘制放大后的图片resultImg.getGraphics().drawImage(srcImg, 0, 0, w1, h1, null);return resultImg;}/*** 旋转图片-90度** @param width  目标图像宽度* @param height 目标图像高度* @return*/public static void rotateImage(int width, int height, int[] imageArray) {int[][] arr = new int[height][width];int x = 0;int y = 0;for (int i = 0; i < imageArray.length; i++) {arr[y][x++] = imageArray[i];if (x % width == 0) {x = 0;y++;}}//旋转-90度int index = 0;for (int j = width - 1; j >= 0; j--) {for (int i = 0; i < arr.length; i++) {imageArray[index++] = arr[i][j];}}}private static final String SOURCE_FILE_PATH = "C:\\Users\\Administrator\\Pictures\\fee.jpg";private static final String WATER_FILE_PATH = "C:\\Users\\Administrator\\Pictures\\invoiceH.png";private static final String SAVE_FILE_PATH = "C:\\Users\\Administrator\\Pictures\\overlyingImageNew.jpg";/*** @param fileUrl 文件绝对路径或相对路径* @return 读取到的缓存图像* @throws IOException 路径错误或者不存在该文件时抛出IO异常*/public static BufferedImage getBufferedImage(String fileUrl)throws IOException {File f = new File(fileUrl);return ImageIO.read(f);}/*** 输出图片** @param buffImg  图像拼接叠加之后的BufferedImage对象* @param savePath 图像拼接叠加之后的保存路径*/public static void generateSaveFile(BufferedImage buffImg, String savePath) {int temp = savePath.lastIndexOf(".") + 1;try {File outFile = new File(savePath);if (!outFile.exists()) {outFile.createNewFile();}ImageIO.write(buffImg, savePath.substring(temp), outFile);System.out.println("ImageIO write...");} catch (IOException e) {e.printStackTrace();}}/*** Java 测试图片合并方法*/public static void imageMargeTest() {// 读取待合并的文件BufferedImage bi1 = null;BufferedImage bi2 = null;// 调用mergeImage方法获得合并后的图像BufferedImage destImg = null;System.out.println("下面是垂直合并的情况：");String saveFilePath = WATER_FILE_PATH;String divingPath = SOURCE_FILE_PATH;String margeImagePath = SAVE_FILE_PATH;try {bi1 = getBufferedImage(saveFilePath);bi2 = getBufferedImage(divingPath);// 调用mergeImage方法获得合并后的图像destImg = mergeImage(bi1, bi2);} catch (IOException e) {e.printStackTrace();}// 保存图像generateSaveFile(destImg, margeImagePath);System.out.println("垂直合并完毕!");}public static void main(String[] args) {// 测试图片的垂直合并imageMargeTest();}}