前言:

你知道的这只是一个简单笔记......

生成商品海报图片需要处理两个问题：

1）将文字和二维码合成为一张图片；

2）将图片保存到文件。

依赖:

其中，com.google.zxing是一个二维码处理库，com.itextpdf是一个PDF处理库，org.apache.commons.lang3是一个常用的Java工具库。这些库可以通过Maven中央仓库进行下载和引用。

<dependency><groupId>com.google.zxing</groupId><artifactId>core</artifactId><version>3.4.1</version>
</dependency>
<dependency><groupId>com.google.zxing</groupId><artifactId>javase</artifactId><version>3.4.1</version>
</dependency>
<dependency><groupId>com.itextpdf</groupId><artifactId>itextpdf</artifactId><version>5.5.13</version>
</dependency>
<dependency><groupId>org.apache.commons</groupId><artifactId>commons-lang3</artifactId><version>3.12.0</version>
</dependency>

编写生成海报代码

生成海报代码可以分为两个部分，分别处理文字和二维码。

处理文字

处理文字需要使用iText库，通过创建PDF文档、设置字体、添加文本、设置位置等方式生成一个带有文字的PDF页面，然后将PDF页面转换为图片。

代码如下:

import com.itextpdf.text.*;
import com.itextpdf.text.pdf.PdfContentByte;
import com.itextpdf.text.pdf.PdfWriter;
import org.apache.commons.lang3.StringUtils;import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;public class PosterGenerator {private static final String FONT_PATH = "src/main/resources/msyh.ttf";/*** 生成带有文字的海报图片** @param text      文字内容* @param imageSize 图片大小* @param fontName  字体名称* @param fontSize  字体大小* @return 生成的海报图片*/public static BufferedImage generateTextPoster(String text, int imageSize, String fontName, float fontSize) throws DocumentException, IOException {Document document = new Document();PdfWriter writer = PdfWriter.getInstance(document, new ByteArrayOutputStream());document.open();PdfContentByte contentByte = writer.getDirectContent();Font font = FontFactory.getFont(fontName, BaseFont.IDENTITY_H, BaseFont.EMBEDDED, fontSize);Phrase phrase = new Phrase(text, font);ColumnText.showTextAligned(contentByte, Element.ALIGN_CENTER, phrase, imageSize / 2, imageSize / 2, 0);document.close();ByteArrayOutputStream baos = (ByteArrayOutputStream) writer.getDirectContent().getOutputStream();byte[] pdfBytes = baos.toByteArray();return convertPDFToImage(pdfBytes, imageSize, imageSize);}private static BufferedImage convertPDFToImage(byte[] pdfBytes, int width, int height) throws IOException {Image image = Image.getInstance(pdfBytes);BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);Graphics2D graphics = bufferedImage.createGraphics();graphics.setColor(Color.WHITE);graphics.fillRect(0, 0, width, height);graphics.drawImage(image, 0, 0, width, height, null);graphics.dispose();return bufferedImage;}
}

代码中，generateTextPoster方法用于生成带有文字的海报图片。首先创建一个PDF文档，设置字体、添加文本、设置位置等，然后将PDF文档转换为图片。convertPDFToImage方法用于将PDF文档转换为BufferedImage类型的图片。
处理二维码

处理二维码需要使用Google的ZXing库，通过创建二维码内容、设置参数等方式生成二维码图片。

代码如下:

import com.google.zxing.BarcodeFormat;
import com.google.zxing.EncodeHintType;
import com.google.zxing.WriterException;
import com.google.zxing.common.BitMatrix;
import com.google.zxing.qrcode.QRCodeWriter;import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;public class PosterGenerator {/*** 生成带有文字和二维码的海报图片** @param text         文字内容* @param imageSize    图片大小* @param fontName     字体名称* @param fontSize     字体大小* @param qrCodeString 二维码内容* @param qrCodeSize   二维码大小* @param qrCodeX      二维码X坐标* @param qrCodeY      二维码Y坐标* @return 生成的海报图片*/public static BufferedImage generatePoster(String text, int imageSize, String fontName, float fontSize,String qrCodeString, int qrCodeSize, int qrCodeX, int qrCodeY) throws Exception {BufferedImage textImage = generateTextPoster(text, imageSize, fontName, fontSize);BufferedImage qrCodeImage = generateQRCode(qrCodeString, qrCodeSize);Graphics2D graphics = textImage.createGraphics();graphics.drawImage(qrCodeImage, qrCodeX, qrCodeY, null);graphics.dispose();return textImage;}/*** 生成带有文字的海报图片** @param text      文字内容* @param imageSize 图片大小* @param fontName  字体名称* @param fontSize  字体大小* @return 生成的海报图片*/public static BufferedImage generateTextPoster(String text, int imageSize, String fontName, float fontSize) throws Exception {Document document = new Document();PdfWriter writer = PdfWriter.getInstance(document, new ByteArrayOutputStream());document.open();PdfContentByte contentByte = writer.getDirectContent();Font font = FontFactory.getFont(fontName, BaseFont.IDENTITY_H, BaseFont.EMBEDDED, fontSize);Phrase phrase = new Phrase(text, font);ColumnText.showTextAligned(contentByte, Element.ALIGN_CENTER, phrase, imageSize / 2, imageSize / 2, 0);document.close();ByteArrayOutputStream baos = (ByteArrayOutputStream) writer.getDirectContent().getOutputStream();byte[] pdfBytes = baos.toByteArray();return convertPDFToImage(pdfBytes, imageSize, imageSize);}/*** 生成二维码图片** @param qrCodeString 二维码内容* @param size         二维码大小* @return 生成的二维码图片*/public static BufferedImage generateQRCode(String qrCodeString, int size) throws WriterException, IOException {Map<EncodeHintType, Object> hints = new HashMap<>();hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");QRCodeWriter qrCodeWriter = new QRCodeWriter();BitMatrix bitMatrix = qrCodeWriter.encode(qrCodeString, BarcodeFormat.QR_CODE, size, size, hints);BufferedImage qrCodeImage = new BufferedImage(size, size, BufferedImage.TYPE_INT_RGB);for (int x = 0; x < size; x++) {for (int y = 0; y < size; y++) {qrCodeImage.setRGB(x, y, bitMatrix.get(x, y) ? Color.BLACK.getRGB() : Color.WHITE.getRGB());}}return qrCodeImage;}private static BufferedImage convertPDFToImage(byte[] pdfBytes, int width, int height) throws IOException {Image image = Image.getInstance(pdfBytes);BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);Graphics2D graphics = bufferedImage.createGraphics();graphics.setColor(Color.WHITE);graphics.fillRect(0, 0, width, height);graphics.drawImage(image, 0, 0, width, height, null);graphics.dispose();return bufferedImage;}public static void main(String[] args) throws Exception {String text = "这是一段测试文字，用于生成海报";String qrCodeString = "https://www.baidu.com/";int imageSize = 600;int qrCodeSize =

另一个方法:

将文字和二维码合成为一张图片，需要将二维码图片放置到文字图片上，并设置二维码的位置和大小。

示例代码如下：

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.HashMap;
import java.util.Map;public class PosterGenerator {private static final String FONT_PATH = "src/main/resources/msyh.ttf";/*** 生成带有文字和二维码的海报图片** @param text         文字内容* @param imageSize    图片大小* @param fontName     字体名称* @param fontSize     字体大小* @param qrCodeString 二维码内容* @param qrCodeSize   二维码大小* @param qrCodeX      二维码X坐标* @param qrCodeY      二维码Y坐标* @return 生成的海报图片*/public static BufferedImage generatePoster(String text, int imageSize, String fontName, float fontSize,String qrCodeString, int qrCodeSize, int qrCodeX, int qrCodeY) throws Exception {BufferedImage textImage = generateTextPoster(text, imageSize, fontName, fontSize);BufferedImage qrCodeImage = generateQRCode(qrCodeString, qrCodeSize);Graphics2D graphics = textImage.createGraphics();graphics.drawImage(qrCodeImage, qrCodeX, qrCodeY, null);graphics.dispose();return textImage;}/*** 生成带有文字的海报图片** @param text      文字内容* @param imageSize 图片大小* @param fontName  字体名称* @param fontSize  字体大小* @return 生成的海报图片*/public static BufferedImage generateTextPoster(String text, int imageSize, String fontName, float fontSize) throws Exception {Document document = new Document();PdfWriter writer = PdfWriter.getInstance(document, new ByteArrayOutputStream());document.open();PdfContentByte contentByte = writer.getDirectContent();Font font = FontFactory.getFont(fontName, BaseFont.IDENTITY_H, BaseFont.EMBEDDED, fontSize);Phrase phrase = new Phrase(text, font);ColumnText.showTextAligned(contentByte, Element.ALIGN_CENTER, phrase, imageSize / 2, imageSize / 2, 0);document.close();ByteArrayOutputStream baos = (ByteArrayOutputStream) writer.getDirectContent().getOutputStream();byte[] pdfBytes = baos.toByteArray();return convertPDFToImage(pdfBytes, imageSize, imageSize);}/*** 生成二维码图片** @param qrCodeString 二维码内容* @param size         二维码大小* @return 生成的二维码图片*/public static BufferedImage generateQRCode(String qrCodeString, int size) throws WriterException {Map<EncodeHintType, Object> hints = new HashMap<>();hints.put(EncodeHintType.CHARACTER_SET, "UTF-8");BitMatrix bitMatrix = new MultiFormatWriter().encode(qrCodeString, BarcodeFormat.QR_CODE, size, size, hints);int width = bitMatrix.getWidth();int height = bitMatrix.getHeight();BufferedImage qrCodeImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);for (int x = 0; x < width; x++) {for (int y = 0; y < height; y++) {qrCodeImage.setRGB(x, y, bitMatrix.get(x, y) ? Color.BLACK.getRGB() : Color.WHITE.getRGB());}}return qrCodeImage;}private static BufferedImage convertPDFToImage(byte[] pdfBytes, int width, int height) throws IOException {Image image = Image.getInstance(pdfBytes);BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);Graphics2D graphics = bufferedImage.createGraphics();graphics.setColor(Color.WHITE);graphics.fillRect(0, 0, width, height);graphics.drawImage(image, 0, 0, width, height, null);graphics.dispose();return bufferedImage;}public static void main(String[] args) throws Exception {String text = "这是一段测试文字，用于生成海报";String qrCodeString = "https://www.baidu.com/";int imageSize = 600;int qrCodeSize = 200;int qrCodeX = 200;int qrCodeY = 200;String fontPath = "src/main/resources/msyh.ttf";float fontSize = 30;BufferedImage posterImage = generatePoster(text, imageSize, fontPath, fontSize,qrCodeString, qrCodeSize, qrCodeX, qrCodeY);File outputFile = new File("poster.png");ImageIO.write(posterImage, "png", outputFile);
}
}

补全上面的main测试方法:

public static void main(String[] args) throws Exception {String text = "这是一段测试文字，用于生成海报";String qrCodeString = "https://www.baidu.com/";int imageSize = 600;int qrCodeSize = 200;int qrCodeX = 200;int qrCodeY = 200;String fontPath = "src/main/resources/msyh.ttf";float fontSize = 30;BufferedImage posterImage = generatePoster(text, imageSize, fontPath, fontSize,qrCodeString, qrCodeSize, qrCodeX, qrCodeY);File outputFile = new File("poster.png");ImageIO.write(posterImage, "png", outputFile);
}

在主函数中，我们设置了以下参数：