fisdemo.java

Java语言是目前最流行

//FileInputStream类创建一个能从文件中读取字节的InputStream类
import java.io.*;

class FISDemo
{
	public static void main(String[] args) throws Exception
	{
		int size;
		FileInputStream f = new FileInputStream("FISDemo.java");
		System.out.println("合计可用到的字节:"+(size = f.available()));
		int n = size/40;
		System.out.println("一次"+n+"字节在文件中读取");
		for(int i=0;i<n;i++)
		{
			System.out.print((char) f.read());	
		}
		System.out.println("\n 可读取的字节数:"+f.available());
		//available()返回当前输入流中可读的字节数
		System.out.println("读取下一个"+n+"有一 read([b])");
		byte b[] = new byte[n];
		if(f.read(b)!=n)
		{//试图读取b.length个字节到b中，并返回实际成功读取的字节数。遇到文件尾则返回-1
			System.out.println("couldn't read "+n+" bytes.");	
		}
		System.out.println(new String(b,0,n));
		System.out.println("\t Still Available:"+(size = f.available()));
		System.out.println("skipping half of remaining bytes with skip()");
		f.skip(size/2);
		System.out.println("Still Available:"+f.available());
		System.out.println("reading "+n/2+" into the end of array");
		if(f.read(b,n/2,n/2)!=n/2)
		{
			System.out.println("couldn't read "+n/2+" byte.");	
		}
		System.out.println(new String(b,0,b.length));
		System.out.println("\n Still Available:"+f.available());
		f.close();//关闭输入流并释放系统资源
	}	
}