java中的Base64 UTF-32解码不能按预期工作

import java.nio.charset.StandardCharsets;
import java.util.Base64;

public class Base64Example {
    public static void main(String[] args) {
        String utf32String = "Hello, 世界!";
        
        // 将UTF-32字符串转换为Base64编码
        byte[] utf32Bytes = utf32String.getBytes(StandardCharsets.UTF_32);
        String base64String = Base64.getEncoder().encodeToString(utf32Bytes);
        
        System.out.println("Base64编码: " + base64String);
        
        // 将Base64编码的数据解码为UTF-32字符串
        byte[] decodedBytes = Base64.getDecoder().decode(base64String);
        String decodedString = new String(decodedBytes, StandardCharsets.UTF_32);
        
        System.out.println("解码后的UTF-32字符串: " + decodedString);
    }
}