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

所以我的代码有错误吗？

我是否滥用了包装器？

是不是kryo的错误（用3.0.3和4.0.0版本测试过）？

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();
}

Java 8 Base64 流包装器吃掉最后两个字符？

Java 8 Base64 stream wrapper eats last two chars?

java

base64

kryo

java-8