fileradaccess.java

Java语言程序设计-源代码（第三部分）和课程相对应的提供了一些用于学习理解的代码设计

import java.io.*;
public class FileRadAccess{
	public static void main(String args[]){
		String readStr,tempStr;
		int fileLine=0;
		long pointerLast1=0,pointerLast2=0;
		try
		{
			RandomAccessFile f1 = new RandomAccessFile("e:/example.txt","rw");
			while(f1.readLine()!=null)
				fileLine++;
			pointerLast1 = f1.getFilePointer();
			for(int i=0;i<fileLine;i++)
			{
				f1.seek(4*i);
				readStr = f1.readLine();
				System.out.println(readStr);
			}
		}catch(IOException e){
		}
		try
		{
			RandomAccessFile f2 = new RandomAccessFile("e:/example.txt","rw");
			byte buf[] = new byte[1024];
			String writeStr = new String("***************************");
			f2.seek(pointerLast1);
			f2.writeBytes("\r\n"+writeStr+"\r\n");
			f2.seek(0);
			f2.readLine();
			f2.readLine();
			pointerLast2 = f2.getFilePointer();
			f2.read(buf);
			tempStr = new String(buf);
			f2.seek(pointerLast2);
			f2.writeBytes(writeStr+"\r\n");
			f2.writeBytes(tempStr);
		}catch(IOException e){
		}
	}
}