将一维数据编码为方形图像的策略与实现

import java.awt.Color;
import java.awt.image.BufferedImage;

public class SquareImageEncoder {

    /**
     * 将字节值编码为灰度颜色。
     * 为了避免负值，将字节值加上128，使其范围变为0-255。
     *
     * @param byt 要编码的字节
     * @return 对应的灰度Color对象
     */
    public static Color encodeByteToColor(byte byt){
        // byte的范围是-128到127，加上128后变为0到255
        int grayValue = byt + 128;
        return new Color(grayValue, grayValue, grayValue);
    }

    /**
     * 将字符串编码为一个方形的BufferedImage。
     * 图像的尺寸根据字符串的字节长度计算，确保所有数据都能被容纳。
     *
     * @param str 要编码的字符串
     * @return 包含编码数据的方形BufferedImage
     */
    public static BufferedImage encodeStringToSquareImage(String str){
        // 1. 获取字符串的字节表示
        byte[] bytes = str.getBytes();
        int dataLength = bytes.length;

        // 2. 计算方形图像的边长
        // 使用Math.ceil(Math.sqrt(dataLength))确保所有数据都能被容纳
        int imageSideLength = (int) Math.ceil(Math.sqrt(dataLength));

        // 3. 创建BufferedImage对象
        // TYPE_INT_ARGB 支持透明度，未填充的像素将默认为透明黑色
        BufferedImage img = new BufferedImage(imageSideLength, imageSideLength, BufferedImage.TYPE_INT_ARGB);

        // 4. 遍历字节数组，将每个字节映射到图像的像素
        for (int index = 0; index < dataLength; index++) {
            // 计算当前字节在图像中的二维坐标
            int x = index % imageSideLength;
            int y = (int) Math.floor(index / (float)imageSideLength); // 使用浮点数除法确保精确计算y坐标

            // 获取字节对应的颜色
            int pixelColor = encodeByteToColor(bytes[index]).getRGB();

            // 设置像素颜色
            img.setRGB(x, y, pixelColor);
        }

        return img;
    }

    public static void main(String[] args) {
        String testString1 = "Hello World!"; // 12 bytes
        BufferedImage img1 = encodeStringToSquareImage(testString1);
        System.out.println("Image 1 created: " + img1.getWidth() + "x" + img1.getHeight()); // Expected: 4x4 (sqrt(12) approx 3.46, ceil is 4)

        String testString2 = "abcdefghijklmnopqrstuvwxy"; // 25 bytes
        BufferedImage img2 = encodeStringToSquareImage(testString2);
        System.out.println("Image 2 created: " + img2.getWidth() + "x" + img2.getHeight()); // Expected: 5x5 (sqrt(25) is 5)

        String testString3 = "a"; // 1 byte
        BufferedImage img3 = encodeStringToSquareImage(testString3);
        System.out.println("Image 3 created: " + img3.getWidth() + "x" + img3.getHeight()); // Expected: 1x1 (sqrt(1) is 1)

        String testString4 = "This is a longer string with more data to fill up a larger square image."; // 71 bytes
        BufferedImage img4 = encodeStringToSquareImage(testString4);
        System.out.println("Image 4 created: " + img4.getWidth() + "x" + img4.getHeight()); // Expected: 9x9 (sqrt(71) approx 8.42, ceil is 9)
    }
}