Today, I made a Java multi-image merge to generate a long pdf image. It feels good. Share it with everyone. The
pixels of the image must be consistent. ImageIO will use the largest image width as the benchmark when merging images, and other images are smaller than this width. The black box will be filled. I provide a method for image scaling, which can be used to zoom the image to ensure that the width and height of the image are consistent, especially the width. It doesn’t matter whether the height is consistent or not.
Research is not easy, if it helps you, please keep repeating. Thanks!
import com.itextpdf.text.Document;
import com.itextpdf.text.Image;
import com.itextpdf.text.Rectangle;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfWriter;
import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.util.ArrayList;
import java.util.List;
public class CreateImagePdf {
public static void main(String[] args) {
try {
/**
* 缩放图片
*/
scaleImages();
// 需要合并的图片文件列表（缩放后的图片）
List<String> imageFiles = new ArrayList<>();
imageFiles.add("E:\\newYsj1\\1.jpg");
imageFiles.add("E:\\newYsj1\\2.jpg");
imageFiles.add("E:\\newYsj1\\3.jpg");
imageFiles.add("E:\\newYsj1\\4.jpg");
imageFiles.add("E:\\newYsj1\\5.jpg");
imageFiles.add("E:\\newYsj1\\6.jpg");
imageFiles.add("E:\\newYsj1\\7.jpg");
imageFiles.add("E:\\newYsj1\\8.jpg");
imageFiles.add("E:\\newYsj1\\9.jpg");
imageFiles.add("E:\\newYsj1\\10.jpg");
imageFiles.add("E:\\newYsj1\\11.jpg");
imageFiles.add("E:\\newYsj1\\12.jpg");
// 合并后的长图文件
String mergedImageFile = "E:\\mergedImage.jpg";
//生成一张长图
mergeImages(imageFiles, mergedImageFile);
// 生成PDF文件
String pdfFile = "E:\\mergedImage.pdf";
createPDF(mergedImageFile, pdfFile);
} catch (Exception e) {
e.printStackTrace();
}
}
/**
* 将多个图片文件合并成一张长图
*
* @param imageFiles 图片文件列表
* @param mergedImageFile 合并后的长图文件
* @throws Exception
*/
public static void mergeImages(List<String> imageFiles, String mergedImageFile) throws Exception {
BufferedImage mergedImage = null;
int heightTotal = 0;
int maxWidth = 0;
for (String imageFile : imageFiles) {
BufferedImage image = ImageIO.read(new File(imageFile));
//图片大小不保持一致需要把这个判断注释掉，不然会出现黑框
// if (image.getWidth() > maxWidth) {
maxWidth = image.getWidth();
// }
heightTotal += image.getHeight();
}
mergedImage = new BufferedImage(maxWidth, heightTotal, BufferedImage.TYPE_INT_RGB);
int offsetY = 0;
for (String imageFile : imageFiles) {
BufferedImage image = ImageIO.read(new File(imageFile));
mergedImage.getGraphics().drawImage(image, 0, offsetY, null);
offsetY += image.getHeight();
}
ImageIO.write(mergedImage, "jpg", new File(mergedImageFile));
}
/**
* 将长图文件转换为PDF文件
*
* @param mergedImageFile 长图文件
* @param pdfFile PDF文件
* @throws Exception
*/
public static void createPDF(String mergedImageFile, String pdfFile) throws Exception {
//获取下图片的大小，图片的大小就是document的大小（建议图片就是A4纸的大小就行）
Image image = Image.getInstance(mergedImageFile);
com.itextpdf.text.Rectangle rectangle = new Rectangle(image.getWidth(), image.getHeight());
Document document = new Document(rectangle, 0, 0, 0, 0);
// 创建PdfWriter对象
PdfWriter writer = PdfWriter.getInstance(document, new FileOutputStream(pdfFile));
// 打开文档
document.open();
// 获取PdfContentByte对象
PdfContentByte cb = writer.getDirectContent();
image.scaleToFit(document.getPageSize().getWidth(), document.getPageSize().getHeight());
// 设置图片位置
image.setAbsolutePosition(0, 0);
// 添加图片到PdfContentByte对象
cb.addImage(image);
// 关闭文档
document.close();
}
//缩放图片方法
private static void scaleImages() throws Exception {
// 需要合并的图片文件列表
List<String> imageFiles = new ArrayList<>();
File file = new File("E:\\ysj1");
File[] files = file.listFiles();
for (int i = 0; i < files.length; i++) {
imageFiles.add(files[i].getName());
System.err.println(files[i].getName());
}
for (String imageFile : imageFiles) {
//加载图片
File f = new File("E:\\ysj1\\" + imageFile);
BufferedImage image = ImageIO.read(f);
BufferedImage imag = scaleImage(image, 595, 842);
String[] split = imageFile.split("\\.");
//保存图片
File targetFile = new File("E:\\newYsj1\\" + split[0] + ".jpg");
ImageIO.write(imag, "jpg", targetFile);
}
}
// 等比例缩放图片
private static BufferedImage scaleImage(BufferedImage img, int maxWidth, int maxHeight) {
int width = img.getWidth();
int height = img.getHeight();
// 计算缩放比例
double scale = Math.min((double) maxWidth / width, (double) maxHeight / height);
// 缩放后的图片宽度和高度
int newWidth = (int) (width * scale);
int newHeight = (int) (height * scale);
// 创建缩放后的图片
BufferedImage scaledImage = new BufferedImage(newWidth, newHeight, BufferedImage.TYPE_INT_RGB);
Graphics2D g2d = scaledImage.createGraphics();
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g2d.drawImage(img, 0, 0, newWidth, newHeight, null);
g2d.dispose();
return scaledImage;
}
}