效果：

2020-04-07_084804.png

2020-04-07_084938.png

代码：

package xdemo;

import java.awt.image.BufferedImage;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;

import javax.imageio.ImageIO;
import javax.swing.filechooser.FileSystemView;

public class Test {
        //将本地桌面上的picts文件夹内的图片转化为字符画
    public static void main(String[] args) throws Exception {
        String path1 = FileSystemView.getFileSystemView().getHomeDirectory().getAbsolutePath();
        path1 += "\\picts";
        String pathSource = "";
        String pathTarget = "";
        File picts = new File(path1);
        if (picts.exists()) {
            File[] files = picts.listFiles();
            for (File file : files) {
                // 判断文件是否为图片，支持bmp/gif/jpg/png
                if (ImageIO.read(file) != null) {
                    String fileName = file.getName();
                    pathSource = path1 + "\\" + fileName;
                    pathTarget = path1 + "\\" + fileName.split("\\.")[0] + ".txt";
                    createAsciiPic(pathSource, pathTarget);
                }
            }
        }
    }
    /**
     * @param path
     *            图片路径
     */
    public static void createAsciiPic(final String path, String path2) {
        final String base = "\"@#&$%*o!;.";// 字符串由复杂到简单
        // final String base = "#8XOHLTI)i=+;:,. ";// 字符串由复杂到简单
        try {
            final BufferedImage image = ImageIO.read(new File(path)); // 读取图片
            // 输出到指定文件中
            final BufferedWriter fos = new BufferedWriter(new FileWriter(path2,
                    false)); // true表示是否追加
            for (int y = 0; y < image.getHeight(); y += 2) {
                for (int x = 0; x < image.getWidth(); x++) {
                    final int pixel = image.getRGB(x, y);
                    final int r = (pixel & 0xff0000) >> 16, g = (pixel & 0xff00) >> 8, b = pixel & 0xff;
                    final float gray = 0.299f * r + 0.578f * g + 0.114f * b;
                    final int index = Math.round(gray * (base.length() + 1)
                            / 255);
                    String s = index >= base.length() ? " " : String.valueOf(base.charAt(index));
                    fos.write(s);
                }
                fos.newLine();
            }
            fos.close();
        } catch (final IOException e) {
            e.printStackTrace();
        }
    }
}