mark长度和缓存区大小中有一个大于文件大小都可以实现返回到mark 位置

实例：
import java.io.BufferedInputStream;
import java.io.BufferedOutputStream;
import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.FileOutputStream;
import java.io.IOException;

public class BufferedStreamDemo {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    FileInputStream fInputStream =null ;
    FileOutputStream fOutputStream =null ;
    BufferedInputStream fBufferedInputStream =null;
    BufferedOutputStream fBufferedOutputStream = null;
    
    try {
        fInputStream =new FileInputStream("e:/io/a.txt");
        fOutputStream =new FileOutputStream("e:/io/b.txt");
        // 处理流的构造函数必须以一个流对象做参数
        fBufferedInputStream = new BufferedInputStream(fInputStream,5); // 缓冲区默认为32字节   如果发到32字节会自动清空缓冲区
        fBufferedOutputStream = new BufferedOutputStream(fOutputStream);
        
        int b;
        fBufferedInputStream.mark(15); // mark长度和缓存区大小中有一个大于文件大小都可以实现返回到mark 位置
        try {
            while((b = fBufferedInputStream.read()) !=-1){
                char c = (char) b;
                System.out.print(c+" ");
                fBufferedOutputStream.write(b);
            }
            System.out.println();
            fBufferedInputStream.reset();
            while((b = fBufferedInputStream.read()) !=-1){
                char c = (char) b;
                System.out.print(c+" ");
            }
            
            fBufferedOutputStream.flush();
            
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    } catch (FileNotFoundException e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    } finally { 
        
        try {
            
            // 关闭自动清空缓存区，数据保存
            fInputStream.close();
            fOutputStream.close();
            fBufferedInputStream.close();
            fBufferedOutputStream.close();
        } catch (IOException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        
    }
    
}

}