How to use Java to implement the image watermark function of the CMS system

Abstract: Adding the image watermark function to the CMS system can effectively prevent images from being tampered with and stolen. This article will introduce how to use Java to implement the image watermark function of the CMS system and provide code examples.

1. Introduction
   With the popularity of the Internet and the popularity of digital cameras, the theft and tampering of pictures has become a common problem. In order to protect the copyright of images, many CMS systems will add image watermark functions. Image watermark is a technology that adds some identifiable information to the image, such as shooting time, copyright information, etc., in order to identify the copyright ownership of the image.
2. The basic principle of implementing the image watermark function
   The basic principle of implementing the image watermark function is to add some text or graphics to the image, and the transparency and position can be adjusted to achieve the effect without affecting the content of the original image. In Java, you can use the Java 2D API to implement the watermark function of images.
3. Steps to add image watermark
   In order to implement the image watermark function, you need to follow the following steps:

Step 1: Load the image
First, you need to load the image that needs to be added Watermark pictures. You can use Java's ImageIO class to load images. The code is as follows:

File file = new File("image.jpg");
BufferedImage image = ImageIO.read(file);

Step 2: Create a Graphics object
To operate the image by creating a Graphics object, the code is as follows:

Graphics2D g2d = (Graphics2D) image.getGraphics();

Step 3: Add watermark
Before adding a watermark to the picture, you can first set the font, font size, transparency and other attributes. Then, use the corresponding method of the Graphics object to draw text or graphics on the image. The code is as follows:

Font font = new Font("Arial", Font.BOLD, 12);
g2d.setFont(font);
g2d.setColor(Color.RED);
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
g2d.drawString("Copyright", 10, 10);

Step 4: Save the image
After adding the watermark, you need to save the image to the disk. The code is as follows:

ImageIO.write(image, "jpg", new File("watermarked_image.jpg"));

Complete code example:

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import javax.imageio.ImageIO;

public class ImageWatermark {

    public static void main(String[] args) {
        try {
            // 加載圖片
            File file = new File("image.jpg");
            BufferedImage image = ImageIO.read(file);
            
            // 創(chuàng)建Graphics對象
            Graphics2D g2d = (Graphics2D) image.getGraphics();
            
            // 添加水印
            Font font = new Font("Arial", Font.BOLD, 12);
            g2d.setFont(font);
            g2d.setColor(Color.RED);
            g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER, 0.5f));
            g2d.drawString("Copyright", 10, 10);

            // 保存圖片
            ImageIO.write(image, "jpg", new File("watermarked_image.jpg"));
        } catch (Exception e) {
            e.printStackTrace();
        }
    }
}

4. Summary
   By using Java’s Java 2D API, we can easily implement the image watermark function of the CMS system. The above code example demonstrates how to load an image, create a Graphics object, add a watermark, and save the watermarked image to disk. According to specific needs, parameters such as font and transparency can be adjusted to achieve different effects. Implementing the image watermark function can effectively protect the copyright of images, prevent image theft and tampering, and provide greater protection for authors.

Reference link:

• Java official documentation: https://docs.oracle.com/javase/8/docs/api/java/awt/Graphics2D.html

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