如何将 UTF-8 byteOffset 转换为 Java String 的 charOffset？

import java.nio.ByteBuffer;
import java.nio.charset.Charset;

public class Main {
    public static void main(String[] args) {
        String str = "这是一个测试字符串";
        int byteOffset = 6; // 假设您想要获取第6个字节的 charOffset

        ByteBuffer byteBuffer = Charset.forName("UTF-8").encode(str);
        int charOffset = byteBuffer.position(byteOffset).get();

        System.out.println("charOffset: " + charOffset);
    }
}

import java.nio.ByteBuffer;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.CharsetDecoder;

public class Main {
    public static void main(String[] args) {
        String str = "这是一个测试字符串";
        int byteOffset = 6; // 假设您想要获取第6个字节的 charOffset

        CharsetDecoder decoder = Charset.forName("UTF-8").newDecoder();
        CharBuffer charBuffer = decoder.decode(ByteBuffer.wrap(str.getBytes("UTF-8")));

        int charOffset = charBuffer.position(byteOffset).get();
        System.out.println("charOffset: " + charOffset);
    }
}