这是Plexus CommandlineUtils的工作方式：
Process p;p = cl.execute();...if ( timeoutInSeconds <= 0 ){ returnValue = p.waitFor();}else{ long now = System.currentTimeMillis(); long timeoutInMillis = 1000L * timeoutInSeconds; long finish = now + timeoutInMillis; while ( isAlive( p ) && ( System.currentTimeMillis() < finish ) ) { Thread.sleep( 10 ); } if ( isAlive( p ) ) { throw new InterruptedException( "Process timeout out after " + timeoutInSeconds + " seconds" ); } returnValue = p.exitValue();}public static boolean isAlive( Process p ) { try { p.exitValue(); return false; } catch (IllegalThreadStateException e) { return true; }}
