Java InputStream Read Bytes readBytes(InputStream in, int expectedBytes, long timeoutMs)

Description

Read expectedBytes from an input stream and time out if no change on the input stream for more than timeoutMs.
Bytes are read from the input stream as they become available.

License

Apache License

Parameter

Parameter	Description
in	a parameter
expectedBytes	the total number of bytes to read, a byte array of this size is created
timeoutMs	a parameter

Exception

Parameter	Description
TimeoutException	an exception
IOException	an exception

Declaration

public static final byte[] readBytes(InputStream in, int expectedBytes,
        long timeoutMs) throws TimeoutException, IOException,
        InterruptedException 

Method Source Code

//package com.java2s;
//License from project: Apache License 

import java.io.IOException;
import java.io.InputStream;

import java.util.concurrent.TimeoutException;

public class Main {
    /**//from w  ww .j a va2s  . c om
     * Read expectedBytes from an input stream and time out if no change on the input stream for more than timeoutMs.<br/>
     * Bytes are read from the input stream as they become available.
     * @param in
     * @param expectedBytes the total number of bytes to read, a byte array of this size is created
     * @param timeoutMs
     * @throws TimeoutException
     * @throws IOException
     * @return
     */
    public static final byte[] readBytes(InputStream in, int expectedBytes,
            long timeoutMs) throws TimeoutException, IOException,
            InterruptedException {
        byte[] bytes = new byte[expectedBytes];
        int pos = 0;
        long lastTimeAvailable = System.currentTimeMillis();

        do {
            int avail = in.available();
            if (avail > 0) {
                //have an new data, read the available bytes and add to the byte array, note we use expectedBytes-pos, to calculate the remaining bytes
                //required to read
                int btsRead = in.read(bytes, pos,
                        Math.min(avail, expectedBytes - pos));
                pos += btsRead;

                if (pos >= expectedBytes) //we've read all required bytes, exit the loop
                    break;

                //save the last time data was available
                lastTimeAvailable = System.currentTimeMillis();
            } else if ((System.currentTimeMillis() - lastTimeAvailable) > timeoutMs) {
                //check for timeout
                throw new TimeoutException(
                        "Timeout while reading data from the input stream: got only "
                                + pos
                                + " bytes of "
                                + expectedBytes
                                + " last seen "
                                + lastTimeAvailable
                                + " diff "
                                + (System.currentTimeMillis() - lastTimeAvailable));
            } else {
                //sleep to simulate IO blocking and avoid consuming CPU resources on IO wait
                Thread.sleep(100);
            }

        } while (true);

        return bytes;
    }
}

Related

1. readBytes(InputStream in, byte[] buffer)
2. readBytes(InputStream in, byte[] buffer, int maxBytesAtOnce)
3. readBytes(InputStream in, byte[] data, int offset, int length)
4. readBytes(InputStream in, int bufferSize, boolean forceClose)
5. readBytes(InputStream in, int bytesToRead, byte[] buffer, int bufferOffset)
6. readBytes(InputStream in, int len, boolean isLE)
7. readBytes(InputStream in, int length)
8. readBytes(InputStream in, int maxLeng)
9. readBytes(InputStream in, long len)