无法使用java解码文本文件中的base64图像

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.Base64;

public class Base64ImageDecoder {
    public static void main(String[] args) {
        String filePath = "path/to/textfile.txt";
        String outputFilePath = "path/to/outputimage.png";

        try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {
            StringBuilder sb = new StringBuilder();
            String line;
            while ((line = reader.readLine()) != null) {
                sb.append(line);
            }
            String base64Image = sb.toString();

            // 解码Base64图像
            byte[] decodedImage = Base64.getDecoder().decode(base64Image);

            // 保存解码后的图像
            try (BufferedWriter writer = new BufferedWriter(new FileWriter(outputFilePath))) {
                writer.write(decodedImage);
            }

            System.out.println("Base64图像解码成功，并保存为文件：" + outputFilePath);
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}