练习题08File、IO

1、创建一个文件文件中的内容是
name=张三
age =12 pwd=234
读取文件在控制台打印
张三
12
234

package com.xxx;

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


public class Homework1 {
    public static void main(String[] args) throws IOException {
        InputStream is = new FileInputStream("d:\\a\\b\\zhangsan.txt");
        byte[] buffer = new byte[1024];//存储读取到的数据 缓冲数组 的长度一般是1024的倍数，因为与计算机的处理单位。 理论上缓冲数组越大，效率越高
//        String s = "";
        int length = 0;//保存每次读取到的字节个数。
        while ((length = is.read(buffer)) != -1) {//read方法如果读取到了文件的末尾，那么会返回-1表示。
//            System.out.println(new String(buffer, 0, length));
            String s = new String(buffer, 0, length);
            String[] split = s.split("  ");
            for (int i = 0; i < split.length; i++) {
                int index = split[i].indexOf("=");
                String str = split[i].substring(index + 1);
            System.out.println(str);
            }
//            s += (char)length + "";
//            System.out.println(s);
        }


        is.close();
    }
}

2、使用代码在创建这个一个文件d: \admin\dd\1. txt
向文件中写入admin 12345
再将文件中的内容读取出来只将admin写入到 d:\a\b\2. txt中

package com.xxx;

import java.io.*;

public class Homework2 {
    public static void main(String[] args) throws IOException {
        File file = new File("d:\\a\\b\\111.txt");
        file.createNewFile();

        String s = "admin 12345";
        byte[] bytes = s.getBytes();


        InputStream is = new FileInputStream(file);
        BufferedInputStream bis = new BufferedInputStream(is);
        OutputStream os = new FileOutputStream("d:\\a\\b\\222.txt");
        BufferedOutputStream bos = new BufferedOutputStream(os);

        os.write(bytes);

        int length = -1;
        while ((length = bis.read()) != -1) {
            bos.write(length);
        }
    }
}

3、创建一个文件文件中的内容adhdheeuyrydhhddgddhdhddddsvsjssjsjdhdfbfd 将使用高效流读取文件中的内容
存入到1ist集合中统计出a=3 b=2

package com.xxx;

import java.io.BufferedInputStream;
import java.io.FileInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

public class Homework3 {
    public static void main(String[] args) throws IOException {
        InputStream is = new FileInputStream("d:\\a\\b\\new.txt");
        BufferedInputStream bis = new BufferedInputStream(is);

        List<Character> list = new ArrayList<Character>();
        int length = -1;
        while ((length = bis.read()) != -1) {
//            System.out.print((char)length);
            list.add((char)length);
        }
//        System.out.println(list);

        countOfList(list);
    }

    public static Map<Character,Integer> countOfList(List<Character> list) {
        Map<Character, Integer> map = new HashMap<>();
        list.forEach(c -> {Integer counts = map.get(c);map.put(c,counts == null ? 1 : ++counts); });
        System.out.println(map);
        return map;
    }
}

4、将c盘的音频复制到d盘中

package com.xxx;

import java.io.*;

public class Homework4 {
    public static void main(String[] args) throws IOException {

        InputStream is = new FileInputStream("d:\\a\\b\\old.mp3");
        BufferedInputStream bis = new BufferedInputStream(is);

        OutputStream os = new FileOutputStream("d:\\a\\old.mp3");
        BufferedOutputStream bos = new BufferedOutputStream(os);

        int length = -1;
        while ((length = bis.read()) != -1) {
            bos.write(length);
        }

        bos.close();
        bis.close();
        os.close();
        is.close();

    }
}