Java问题记录

1.I/O  在循环中 read方法多次循环是怎么接着上次循环到的末尾当做本次循环起始的？

fis=new FileInputStream("D:\\from.txt");  
			fos=new FileOutputStream("D:\\to.txt");  
		 
			System.out.println(fis+"");
			
			byte b[] = new byte[100];  
			
			while(true){
				int read = fis.read(b,0,b.length); 
				
				if(read == -1) break;
				
				fos.write(b,0,read);
			}