Java怎么给图片加水印

在Java中给图片加水印可以通过以下步骤实现：

1. 导入相关的类库：

import java.awt.AlphaComposite; import java.awt.Font; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO; 

2. 加载原始图片和水印图片：

BufferedImage originalImage = ImageIO.read(new File("original.jpg")); BufferedImage watermarkImage = ImageIO.read(new File("watermark.png")); 

3. 创建一个新的图片对象，大小与原始图片相同：

BufferedImage combinedImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_INT_RGB); 

4. 创建一个图形对象并设置抗锯齿和渲染模式：

Graphics2D graphics = (Graphics2D) combinedImage.getGraphics(); graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON); graphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY); 

5. 将原始图片绘制到新的图片对象上：

graphics.drawImage(originalImage, 0, 0, null); 

6. 设置水印图片的透明度和位置，并绘制到新的图片对象上：

AlphaComposite alphaComposite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f); // 设置透明度为0.5 graphics.setComposite(alphaComposite);  int x = combinedImage.getWidth() - watermarkImage.getWidth() - 10; // 水印图片的x坐标 int y = combinedImage.getHeight() - watermarkImage.getHeight() - 10; // 水印图片的y坐标 graphics.drawImage(watermarkImage, x, y, null); 

7. 添加水印文本：

graphics.setFont(new Font("Arial", Font.BOLD, 12)); graphics.drawString("watermark", 10, 20); 

8. 保存新的图片对象为文件：

ImageIO.write(combinedImage, "JPEG", new File("result.jpg")); 

完整示例代码如下：

import java.awt.AlphaComposite; import java.awt.Font; import java.awt.Graphics2D; import java.awt.RenderingHints; import java.awt.image.BufferedImage; import java.io.File; import javax.imageio.ImageIO;  public class ImageWatermarkExample {     public static void main(String[] args) {         try {             BufferedImage originalImage = ImageIO.read(new File("original.jpg"));             BufferedImage watermarkImage = ImageIO.read(new File("watermark.png"));              BufferedImage combinedImage = new BufferedImage(originalImage.getWidth(), originalImage.getHeight(), BufferedImage.TYPE_INT_RGB);              Graphics2D graphics = (Graphics2D) combinedImage.getGraphics();             graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);             graphics.setRenderingHint(RenderingHints.KEY_RENDERING, RenderingHints.VALUE_RENDER_QUALITY);              graphics.drawImage(originalImage, 0, 0, null);              AlphaComposite alphaComposite = AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f);             graphics.setComposite(alphaComposite);              int x = combinedImage.getWidth() - watermarkImage.getWidth() - 10;             int y = combinedImage.getHeight() - watermarkImage.getHeight() - 10;             graphics.drawImage(watermarkImage, x, y, null);              graphics.setFont(new Font("Arial", Font.BOLD, 12));             graphics.drawString("watermark", 10, 20);              ImageIO.write(combinedImage, "JPEG", new File("result.jpg"));         } catch (Exception e) {             e.printStackTrace();         }     } } 

以上代码将原始图片和水印图片合并为一张新的图片，保存为result.jpg。其中，original.jpg是原始图片，watermark.png是水印图片，"watermark"是水印文本。您可以根据实际情况修改文件路径和水印位置、透明度等参数。