字节输入流-InputStream demo4

Posted 2020-09-21

package inputstream.cn;

import java.io.File;
import java.io.FileInputStream;
import java.io.InputStream;

/*
 * 改进版 4
 * 使用read()通过循环读取
 * byte[] b = new byte[(int)f.length()];
            for (int i = 0; i < b.length; i++) {
                    b[i] = (byte)is.read();
            }
 */
public class InputStreamDemo4 {
        public static void main(String[] args) throws Exception {
            //使用file 找到一个文件
            File f = new File("d:"+File.separator+"test.txt");
            //通过子类实例化父类
            InputStream is =new FileInputStream(f);
            //开辟一个1024的字节数组，把所有的类容读到此数组中
            byte[] b = new byte[(int)f.length()];
            for (int i = 0; i < b.length; i++) {
                    b[i] = (byte)is.read();
            }
            //关闭输入流
            is.close();
            //打印读的数据,将byte类型转换为string类型输出
            System.out.println(new String(b));
            
        }
    }