Java 8 Base64 流包装器吃掉最后两个字符？

Question

我有以下代码:

public static String encode(Object object)
{
    final String result;

    try (ByteArrayOutputStream bOut = new ByteArrayOutputStream();
         Output output = new Output(bOut))
    {
        KRYO.writeObject(output, object);
        output.flush();
        result = Base64.getUrlEncoder().encodeToString(bOut.toByteArray());
    } catch (IOException e)
    {
        // Do nothing, should never happen!
        throw new RuntimeException("MEGA FAIL");
    }

    return result;
}

public static String encodeTest(Object object)
{
    final String result;

    try (ByteArrayOutputStream bOut = new ByteArrayOutputStream();
         OutputStream base64Out = Base64.getUrlEncoder().wrap(bOut);
         Output output = new Output(base64Out))
    {
        KRYO.writeObject(output, object);
        output.flush();
        result = bOut.toString();
    } catch (IOException e)
    {
        // Do nothing, should never happen!
        throw new RuntimeException("MEGA FAIL");
    }

    return result;
}

测试:

String test = "asdf";
System.out.println(encode(test));
System.out.println(encodeTest(test));

给出输出(使用 kryo 记录器):

00:10 TRACE: [kryo] Write: asdf
00:10 TRACE: [kryo] Object graph complete.
YXNk5g==
00:10 TRACE: [kryo] Write: asdf
00:10 TRACE: [kryo] Object graph complete.
YXNk

那么我的代码有错误吗？

我是否滥用了包装器？

是不是kryo的错误(用3.0.3和4.0.0版本测试)？

Answer 1

根据 Base64.Encoder.wrap() 的文档，您需要在完成后关闭流:

It is recommended to promptly close the returned output stream after use, during which it will flush all possible leftover bytes to the underlying output stream.

在编码器流关闭后调用 bOut.toString() 将解决问题:

public static String encodeTest(Object object)
{
    ByteArrayOutputStream bOut = new ByteArrayOutputStream();
    try (OutputStream base64Out = Base64.getUrlEncoder().wrap(bOut);
         Output output = new Output(base64Out))
    {
        KRYO.writeObject(output, object);
    } catch (IOException e)
    {
        // Do nothing, should never happen!
        throw new RuntimeException("MEGA FAIL");
    }

    return bOut.toString();
}