java - 从输出流中获取输入流

Question

我有一个组件在输出流 (ByteArrayOutputStream) 中为我提供数据，我需要将其写入 SQL 数据库的 blob 字段而不创建临时缓冲区，因此需要获取输入溪流。

基于答案 here和 here我想出了以下方法从输出流中获取输入流:

private PipedInputStream getInputStream(ByteArrayOutputStream outputStream) throws InterruptedException
{
    PipedInputStream pipedInStream = new PipedInputStream();
    Thread copyThread = new Thread(new CopyStreamHelper(outputStream, pipedInStream));
    copyThread.start();
    // Wait for copy to complete
    copyThread.join();
    return pipedInStream;
}

class CopyStreamHelper implements Runnable
{
    private ByteArrayOutputStream outStream;
    private PipedInputStream pipedInStream;

    public CopyStreamHelper (ByteArrayOutputStream _outStream, PipedInputStream _pipedInStream)
    {
        outStream = _outStream;
        pipedInStream = _pipedInStream;
    }

    public void run()
    {
        PipedOutputStream pipedOutStream = null;
        try
        {
            // write the original OutputStream to the PipedOutputStream
            pipedOutStream = new PipedOutputStream(pipedInStream);
            outStream.writeTo(pipedOutStream);
        }
        catch (IOException e) 
        {
            // logging and exception handling should go here
        }
        finally
        {
            IOUtils.closeQuietly(pipedOutStream);
        }
    }
}

请注意，输出流已经包含了写入的数据，它最多可以运行 1-2 MB。然而，无论尝试在两个单独的线程或同一个线程中执行此操作，我发现总是 PipedInputStream 卡在以下位置:

Object.wait(long) line: not available [native method]   
PipedInputStream.awaitSpace() line: not available   

Answer 1

您使解决方案过于复杂

ByteArrayOutputStream baos = ...;
byte[] data = baos.toByteArray();
return new ByteArrayInputStream(data);