Springboot 系列（八）自定义 Banner 与 ASCII 字符图案的收到实现

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|_| |_|_|\__,_|_| |_| |_|\___/ \___/ 版本：${spring-boot.formatted-version}

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 |_| |_|_|\__,_|_| |_| |_|\___/ \___/ 版本：(v2.1.3.RELEASE)
2019-02-25 14:00:31.289  INFO 12312 --- [           main] net.codingme.banner.BannerApplication    : Starting BannerApplication on LAPTOP-L1S5MKTA with PID 12312 (D:\IdeaProjectMy\springboot-git\springboot-banner\target\classes started by Niu in D:\IdeaProjectMy\springboot-git\springboot-banner)
2019-02-25 14:00:31.291  INFO 12312 --- [           main] net.codingme.banner.BannerApplication    : No active profile set, falling back to default profiles: default
2019-02-25 14:00:32.087  INFO 12312 --- [           main] o.s.b.w.embedded.tomcat.TomcatWebServer  : Tomcat initialized with port(s): 8080 (http)

/** 位置：org.springframework.boot.SpringApplicationBannerPrinter */
//方法1：
public Banner print(Environment environment, Class<?> sourceClass, Log logger) {
	    // 获取 banner  调用方法记为2
		Banner banner = getBanner(environment);
		try {
			logger.info(createStringFromBanner(banner, environment, sourceClass));
		}
		catch (UnsupportedEncodingException ex) {
			logger.warn("Failed to create String for banner", ex);
		}
		// 打印 banner
		return new PrintedBanner(banner, sourceClass);
}
// 方法2
private Banner getBanner(Environment environment) {
		Banners banners = new Banners();
		// 获取图片banner，我们只关注这个，调用方法记为3
		banners.addIfNotNull(getImageBanner(environment));
		banners.addIfNotNull(getTextBanner(environment));
		if (banners.hasAtLeastOneBanner()) {
			return banners;
		}
		if (this.fallbackBanner != null) {
			return this.fallbackBanner;
		}
		return DEFAULT_BANNER;
	}
// 方法3
/** 获取自定义banner文件信息 */
private Banner getImageBanner(Environment environment) {
	// BANNER_IMAGE_LOCATION_PROPERTY = "spring.banner.image.location";
		String location = environment.getProperty(BANNER_IMAGE_LOCATION_PROPERTY);
		if (StringUtils.hasLength(location)) {
			Resource resource = this.resourceLoader.getResource(location);
			return resource.exists() ? new ImageBanner(resource) : null;
		}
		// IMAGE_EXTENSION = { "gif", "jpg", "png" };
		for (String ext : IMAGE_EXTENSION) {
			Resource resource = this.resourceLoader.getResource("banner." + ext);
			if (resource.exists()) {
				return new ImageBanner(resource);
			}
		}
		return null;
}

// 位置：org.springframework.boot.ImageBanner#printBanner
private void printBanner(BufferedImage image, int margin, boolean invert,
			PrintStream out) {
		AnsiElement background = invert ? AnsiBackground.BLACK : AnsiBackground.DEFAULT;
		out.print(AnsiOutput.encode(AnsiColor.DEFAULT));
		out.print(AnsiOutput.encode(background));
		out.println();
		out.println();
		AnsiColor lastColor = AnsiColor.DEFAULT;
		// 图片高度遍历
		for (int y = 0; y < image.getHeight(); y++) {
			for (int i = 0; i < margin; i++) {
				out.print(" ");
			}
			// 图片宽度遍历
			for (int x = 0; x < image.getWidth(); x++) {
				// 获取每一个像素点
				Color color = new Color(image.getRGB(x, y), false);
				AnsiColor ansiColor = AnsiColors.getClosest(color);
				if (ansiColor != lastColor) {
					out.print(AnsiOutput.encode(ansiColor));
					lastColor = ansiColor;
				}
				// 像素点转换成字符输出，调用方法记为2
				out.print(getAsciiPixel(color, invert));
			}
			out.println();
		}
		out.print(AnsiOutput.encode(AnsiColor.DEFAULT));
		out.print(AnsiOutput.encode(AnsiBackground.DEFAULT));
		out.println();
	}
// 方法2，像素点转换成字符
	private char getAsciiPixel(Color color, boolean dark) {
		// 根据 color 算出一个亮度值
		double luminance = getLuminance(color, dark);
		for (int i = 0; i < PIXEL.length; i++) {
			// 寻找亮度值匹配的字符
			if (luminance >= (LUMINANCE_START - (i * LUMINANCE_INCREMENT))) {
				// PIXEL = { ' ', '.', '*', ':', 'o', '&', '8', '#', '@' };
				return PIXEL[i];
			}
		}
		return PIXEL[PIXEL.length - 1];
	}

import java.awt.*;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;

import javax.imageio.ImageIO;

/**
 * <p>
 * 根据图片生成字符图案
 * 1.图片大小缩放
 * 2.遍历图片像素点
 * 3.获取图片像素点亮度
 * 4.匹配字符
 * 5.输出图案
 *
 * @Author niujinpeng
 */

public class GeneratorTextImage {
    private static final char[] PIXEL = {'@', '#', '8', '&', 'o', ':', '*', '.', ' '};
    public static void main(String[] args) throws Exception {
        // 图片缩放
        BufferedImage bufferedImage = makeSmallImage("src/main/resources/banner.jpg");
        // 输出
        printImage(bufferedImage);
    }

    public static void printImage(BufferedImage image) throws IOException {
        int width = image.getWidth();
        int height = image.getHeight();
        for (int i = 0; i < height; i++) {
            for (int j = 0; j < width; j++) {
                int rgb = image.getRGB(j, i);
                Color color = new Color(rgb);
                int red = color.getRed();
                int green = color.getGreen();
                int blue = color.getBlue();
                // 一个用于计算RGB像素点亮度的公式
                Double luminace = 0.2126 * red + 0.7152 * green + 0.0722 * blue;
                double index = luminace / (Math.ceil(255 / PIXEL.length) + 0.5);
                System.out.print(PIXEL[(int)(Math.floor(index))]);
            }
            System.out.println();
        }
    }

    public static BufferedImage makeSmallImage(String srcImageName) throws Exception {
        File srcImageFile = new File(srcImageName);
        if (srcImageFile == null) {
            System.out.println("文件不存在");
            return null;
        }
        FileOutputStream fileOutputStream = null;
        BufferedImage tagImage = null;
        Image srcImage = null;
        try {
            srcImage = ImageIO.read(srcImageFile);
            int srcWidth = srcImage.getWidth(null);// 原图片宽度
            int srcHeight = srcImage.getHeight(null);// 原图片高度
            int dstMaxSize = 90;// 目标缩略图的最大宽度/高度，宽度与高度将按比例缩写
            int dstWidth = srcWidth;// 缩略图宽度
            int dstHeight = srcHeight;// 缩略图高度
            float scale = 0;
            // 计算缩略图的宽和高
            if (srcWidth > dstMaxSize) {
                dstWidth = dstMaxSize;
                scale = (float)srcWidth / (float)dstMaxSize;
                dstHeight = Math.round((float)srcHeight / scale);
            }
            srcHeight = dstHeight;
            if (srcHeight > dstMaxSize) {
                dstHeight = dstMaxSize;
                scale = (float)srcHeight / (float)dstMaxSize;
                dstWidth = Math.round((float)dstWidth / scale);
            }
            // 生成缩略图
            tagImage = new BufferedImage(dstWidth, dstHeight, BufferedImage.TYPE_INT_RGB);
            tagImage.getGraphics().drawImage(srcImage, 0, 0, dstWidth, dstHeight, null);
            return tagImage;
        } finally {
            if (fileOutputStream != null) {
                try {
                    fileOutputStream.close();
                } catch (Exception e) {
                }
                fileOutputStream = null;
            }
            tagImage = null;
            srcImage = null;
            System.gc();
        }
    }
}