我正在使用RXTX从串口读取数据。读取是在以下列方式产生的线程内完成的:
CommPortIdentifier portIdentifier = CommPortIdentifier.getPortIdentifier(port);
CommPort comm = portIdentifier.open("Whatever", 2000);
SerialPort serial = (SerialPort)comm;
...settings
Thread t = new Thread(new SerialReader(serial.getInputStream()));
t.start();
SerialReader类实现Runnable并且无限循环,从端口读取并将数据构建到有用的包中,然后再将其发送到其他应用程序。但是,我已将其简化为以下简单性:
public void run() {
ReadableByteChannel byteChan = Channels.newChannel(in); //in = InputStream passed to SerialReader
ByteBuffer buffer = ByteBuffer.allocate(100);
while (true) {
try {
byteChan.read(buffer);
} catch (Exception e) {
System.out.println(e);
}
}
}
当用户单击停止按钮时,将触发以下功能,理论上应关闭输入流并中断阻塞byteChan.read(缓冲区)调用。代码如下:
public void stop() {
t.interrupt();
serial.close();
}
但是,当我运行此代码时,我从未得到一个ClosedByInterruptException,它应该在输入流关闭后触发。此外,执行阻止调用serial.close() - 因为底层输入流仍然在读取调用上阻塞。我已经尝试用byteChan.close()替换中断调用,然后应该导致AsynchronousCloseException,但是,我得到了相同的结果。
对我所缺少的任何帮助都将不胜感激。
答案 0 :(得分:7)
您只能通过包装它来将不支持可中断I / O的流制作成InterruptibleChannel
(并且,无论如何,ReadableByteChannel
不会扩展InterruptibleChannel
)
您必须查看基础InputStream
的合同。 SerialPort.getInputStream()
对结果的可中断性有什么看法?如果它没有说什么,你应该假设它忽略了中断。
对于任何不明确支持可中断性的I / O,唯一的选择通常是从另一个线程关闭流。这可能会立即在对流的调用中阻塞的线程中引发IOException
(尽管它可能不是AsynchronousCloseException
)。
然而,即使这非常依赖于InputStream
的实现 - 而底层操作系统也是一个因素。
请注意ReadableByteChannelImpl
返回的newChannel()
类的源代码注释:
private static class ReadableByteChannelImpl
extends AbstractInterruptibleChannel // Not really interruptible
implements ReadableByteChannel
{
InputStream in;
⋮
答案 1 :(得分:4)
RXTX SerialInputStream(由serial.getInputStream()调用返回的内容)支持超时方案,最终解决了我的所有问题。在创建新的SerialReader对象之前添加以下内容会导致读取不再无限期地阻塞:
serial.enableReceiveTimeout(1000);
在SerialReader对象中,我不得不改变一些东西直接从InputStream读取而不是创建ReadableByteChannel,但是现在,我可以毫无问题地停止并重新启动阅读器。
答案 2 :(得分:1)
我正在使用以下代码关闭rxtx。我运行测试,启动它们并关闭它们,似乎工作正常。我的读者看起来像:
private void addPartsToQueue(final InputStream inputStream) {
byte[] buffer = new byte[1024];
int len = -1;
boolean first = true;
// the read can throw
try {
while ((len = inputStream.read(buffer)) > -1) {
if (len > 0) {
if (first) {
first = false;
t0 = System.currentTimeMillis();
} else
t1 = System.currentTimeMillis();
final String part = new String(new String(buffer, 0, len));
queue.add(part);
//System.out.println(part + " " + (t1 - t0));
}
try {
Thread.sleep(sleep);
} catch (InterruptedException e) {
//System.out.println(Thread.currentThread().getName() + " interrupted " + e);
break;
}
}
} catch (IOException e) {
System.err.println(Thread.currentThread().getName() + " " + e);
//if(interruSystem.err.println(e);
e.printStackTrace();
}
//System.out.println(Thread.currentThread().getName() + " is ending.");
}
感谢
public void shutdown(final Device device) {
shutdown(serialReaderThread);
shutdown(messageAssemblerThread);
serialPort.close();
if (device != null)
device.setSerialPort(null);
}
public static void shutdown(final Thread thread) {
if (thread != null) {
//System.out.println("before intterupt() on thread " + thread.getName() + ", it's state is " + thread.getState());
thread.interrupt();
//System.out.println("after intterupt() on thread " + thread.getName() + ", it's state is " + thread.getState());
try {
Thread.sleep(100);
} catch (InterruptedException e) {
System.out.println(Thread.currentThread().getName() + " was interrupted trying to sleep after interrupting" + thread.getName() + " " + e);
}
//System.out.println("before join() on thread " + thread.getName() + ", it's state is " + thread.getState());
try {
thread.join();
} catch (InterruptedException e) {
System.out.println(Thread.currentThread().getName() + " join interruped");
}
//System.out.println(Thread.currentThread().getName() + " after join() on thread " + thread.getName() + ", it's state is" + thread.getState());
}