Io流InputStream

package inputStream;

import java.io.FileInputStream;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.InputStream;

public class Demo {
    
        public static void main(String[] args) {
            readerFile3();
            // System.out.println("done");
        }
        public static void readerFile() {
            //创建字节输入流的对象
            InputStream in  =null;
            /**
             * 字符流能办到的，字节流也能办到，
             * 字节流能办到的，字符流不一定能办到
             * 字节流能读取图片，视频各种二进制的东西
             */
            try {
    /**
     * 单个字节读取的效率很低
     */
            in = new FileInputStream("e.txt");
    
            
                int num = in.read();
                System.out.println(num);
                System.out.println((char)num);
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }finally {
                if(in!=null) {
                    try {
                        in.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
        public static void readerFile1() {
            //创建字节输入流的对象
            InputStream in  =null;
            
            try {
    /**
     * 单个字节读取的效率很低
     */
            in = new FileInputStream("e.txt");
            
            byte[] bs = new byte[1024];
            int len = in.read(bs);
            System.out.println(new String(bs,0,len));
            
                
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }finally {
                if(in!=null) {
                    try {
                        in.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
        public static void readerFile3() {
            //创建字节输入流的对象
            InputStream in  =null;
            
            try {
    /**
     * 单个字节读取的效率很低
     */
            in = new FileInputStream("e.txt");
    
            byte[] bs = new byte[1024];
            //这里面穿的索引为1的话，就是往索引为1的地方放数据的，索引为0的地方为0，就是什么也没有，
            //所以用这三个参数的构造器，输入的时候是从哪开始，输出的时候也得从哪开始
            
            int len = in.read(bs, 1, 3);
            System.out.println(len);
            System.out.println(new String(bs,1,len));
            } catch (FileNotFoundException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            } catch (IOException e) {
                // TODO Auto-generated catch block
                e.printStackTrace();
            }finally {
                if(in!=null) {
                    try {
                        in.close();
                    } catch (IOException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                    }
                }
            }
        }
}