randomlong.java

发布/订阅系统路由重配算法,可应用于ad hoc环境

package util;

import java.io.*;

public class RandomLong {

	
	static String randomFile = "random";
	static String positionFile = "position";
	
	static int pos;
	
	/**
	 * @param args
	 */
	public static void main(String[] args) {
		
		LineNumberReader posIn;
		PrintWriter posOut;
		BufferedInputStream bytes;
		String line;
		int b;
		long l;
		
		// TODO Auto-generated method stub
		try{
			
			posIn = new LineNumberReader(new FileReader(positionFile));
			line = posIn.readLine();
			pos = Integer.parseInt(line);
			posIn.close();
			
			// overread the first pos bytes
			bytes = new BufferedInputStream(new FileInputStream(randomFile));
			for(int i=0; i<pos; i++){
				bytes.read();
			}
			
			l = 0;
			for(int i=0; i<8; i++){
				l = l << 8;
				b = bytes.read();
				if(b==-1){
					throw new IllegalStateException("EOF reached.");
				}
				l = l | b;
			}
			
			pos += 8;
			posOut = new PrintWriter(new FileWriter(positionFile),true);
			posOut.println(pos);
			
			System.out.println("N盲chster Long: "+l);
		}catch(Exception e){
			System.err.println(e);
			e.printStackTrace();			
		}		
	}

}