java使用nio写【中文与ascii字符（abc123）混合】时，出现不可见字符，其ascii码为0

问题代码demo

public static void main(String[] args) {

        String text = "你好aa";
        final CharBuffer charStreamBuffer = CharBuffer.allocate(8192);

        BufferedReader bufferInput = new BufferedReader(new StringReader(text));
        try {
            int singleBatchSize;
            while ((singleBatchSize = bufferInput.read(charStreamBuffer)) != -1) {
                byte[] array = StandardCharsets.UTF_8.encode((CharBuffer) charStreamBuffer.flip()).array();
                charStreamBuffer.clear();
                System.out.println(Arrays.toString(array));
                System.out.println(singleBatchSize);
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            charStreamBuffer.clear();
        }
    }

output:

[-28, -67, -96, -27, -91, -67, 97, 97, 0]
4

修正后代码demo

public static void main(String[] args) {
        String text = "你ac";
        final CharBuffer charStreamBuffer = CharBuffer.allocate(8192);

        BufferedReader bufferInput = new BufferedReader(new StringReader(text));
        try {
            int singleBatchSize;
            while ((singleBatchSize = bufferInput.read(charStreamBuffer)) != -1) {
                charStreamBuffer.flip();
                ByteBuffer byteBuffer = StandardCharsets.UTF_8.encode(charStreamBuffer);
                System.out.println(byteBuffer);
                System.out.println(byteBuffer.position());
                System.out.println(byteBuffer.limit());
                byte[] array = byteBuffer.array();

                charStreamBuffer.clear();
                System.out.println(Arrays.toString(array));
                System.out.println(singleBatchSize);
            }
        } catch (IOException e) {
            throw new RuntimeException(e);
        } finally {
            charStreamBuffer.clear();
        }
    }

output:

java.nio.HeapByteBuffer[pos=0 lim=5 cap=7]
0
5
[-28, -67, -96, 97, 99]
3

其中关于 limit() 的介绍来自：https://www.cnblogs.com/atwanli/articles/7473795.html