java使用hutool把base64编码转为图片

使用Hutool将Base64编码转换为图片的代码如下：

import cn.hutool.core.codec.Base64;
import cn.hutool.core.io.FileUtil;

public class Base64ToImage {
    public static void main(String[] args) {
        // Base64编码字符串
        String base64Str = "data:image/png;base64,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";

        // 去掉Base64编码字符串中的前缀
        String base64 = base64Str.substring(base64Str.indexOf(",") + 1);

        // 将Base64编码字符串解码为字节数组
        byte[] bytes = Base64.decode(base64);

        // 将字节数组写入图片文件
        FileUtil.writeBytes(bytes, "test.png");
    }
}

其中，使用`Base64.decode()`方法将Base64编码字符串解码为字节数组，然后使用`FileUtil.writeBytes()`方法将字节数组写入图片文件。