“管道”是java.io包的一部分。它是Java的特性，而不是Android特有的。一条“管道”为两个线程建立一个单向的通道。生产者负责写数据，消费者负责读取数据。
下面是一个使用管道流进行通信的例子。
public class PipeExampleActivity extends Activity {
private static final String TAG = "PipeExampleActivity";
private EditText editText;
PipedReader r;
PipedWriter w;
private Thread workerThread;
public void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
r = new PipedReader();
w = new PipedWriter();
try {
w.connect(r);
} catch (IOException e) {
e.printStackTrace();
}
setContentView(R.layout.activity_pipe);
editText = (EditText) findViewById(R.id.edit_text);
editText.addTextChangedListener(new TextWatcher() {
@Override
public void beforeTextChanged(CharSequence charSequence, int start, int count, int after) {
}
@Override
public void onTextChanged(CharSequence charSequence, int start, int before, int count) {
try {
if(count > before) {
w.write(charSequence.subSequence(before, count).toString());
}
} catch (IOException e) {
e.printStackTrace();
}
}
@Override
public void afterTextChanged(Editable editable) {
}
});
workerThread = new Thread(new TextHandlerTask(r));
workerThread.start();
}
@Override
protected void onDestroy() {
super.onDestroy();
workerThread.interrupt();
try {
r.close();
w.close();
} catch (IOException e) {
}
}
private static class TextHandlerTask implements Runnable {
private final PipedReader reader;
public TextHandlerTask(PipedReader reader){
this.reader = reader;
}
@Override
public void run() {
while(!Thread.currentThread().isInterrupted()){
try {
int i;
while((i = reader.read()) != -){
char c = (char) i;
Log.d(TAG, "char = " + c);
}
} catch (IOException e) {
e.printStackTrace();
}
}
}
}
}
在这个例子中，对EditText设置一个TextWatcher监听，一旦EditText的内容发生改变，就向“管道”中输入字符，它就是所谓的生产者。同时，有一个工作线程负责从管道中读取字符，它就是所谓的消费者。这样，就实现了UI线程和工作线程之间的数据通信。