jlibs.core.io

Class PumpedInputStream

java.lang.Object

java.io.InputStream

java.io.PipedInputStream

jlibs.core.io.PumpedInputStream

All Implemented Interfaces:

Closeable, AutoCloseable, Runnable

public abstract class PumpedInputStream
extends PipedInputStream
implements Runnable

This class simplifies usage of PipedInputStream and PipedOutputStream

Using PipedInputStream and PipedOutputStream looks cumbersome.

 PipedInputStream pipedIn = new PipedInputStream();
 final PipedOutputStream pipedOut = new PipedOutputStream(pipedIn);
 final IOException ioEx[] = { null };
 new Thread(){
     @Override
     public void run(){
         try{
             writeDataTo(pipedOut);
             pipedOut.close();
         }catch(IOException ex){
             ioEx[0] = ex;
         }
     }
 }.start();
 readDataFrom(pipedIn);
 pipedIn.close();
 if(ioEx[0]!=null)
     throw new RuntimeException("something gone wrong", ioEx[0]);
 

The same can be achieved using PumpedInputStream as follows:

 PumpedInputStream in = new PumpedInputStream(){
     @Override
     protected void pump(PipedOutputStream out) throws Exception{
         writeDataTo(out);
     }
 }.start(); // start() will spawn new thread
 readDataFrom(in);
 in.close(); // any exceptions occurred in pump(...) are thrown by close()
 

PumpedInputStream is an abstract class with following abstract method:

 protected abstract void pump(PipedOutputStream out) throws Exception;
 

This method implementation should write data into out which is passed as argument and close it.
Any exception thrown by pump(...) are wrapped in IOException and rethrown by PumpedReader.close().

PumpedInputStream implements Runnable which is supposed to be run in thread.
You can use PumpedInputStream.start() method to start thread or spawn thread implicitly.
start() method returns self reference.

 public PumpedInputStream start();
 

The advantage of PumpedInputStream over PipedInputStream/PipedOutputStream/Thread is:

• it doesn't clutter the exising flow of code
• exception handling is better

Author:

Santhosh Kumar T

See Also:

PumpedReader

Field Summary

Fields inherited from class java.io.PipedInputStream

buffer, in, PIPE_SIZE

Constructor Summary

Constructors

Constructor and Description
PumpedInputStream()

Method Summary

Modifier and Type	Method and Description
void	close() Closes this stream and releases any system resources associated with the stream.
protected abstract void	pump(PipedOutputStream out) Subclasse implementation should write data into writer.
void	run()
PumpedInputStream	start() Starts a thread with this instance as runnable.

Methods inherited from class java.io.PipedInputStream

available, connect, read, read, receive

Methods inherited from class java.io.InputStream

mark, markSupported, read, reset, skip

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

PumpedInputStream

public PumpedInputStream()

Method Detail

run

public void run()

Specified by:

run in interface Runnable

start

public PumpedInputStream start()

Starts a thread with this instance as runnable.

Returns:

self reference

close

public void close()
           throws IOException

Closes this stream and releases any system resources associated with the stream.

Any exception thrown by pump(java.io.PipedOutputStream) are cached and rethrown by this method

Specified by:

close in interface Closeable

Specified by:

close in interface AutoCloseable

Overrides:

close in class PipedInputStream

Throws:

IOException - if an I/O error occurs.

pump

protected abstract void pump(PipedOutputStream out)
                      throws Exception

Subclasse implementation should write data into writer.

Parameters:

out - outputstream into which data should be written

Throws:

Exception