常用IO输入输出流

• 字节流不限于读取纯文本格式的文件，对于常见的word、Excel、PPT、MP3、MP4等音频、视频文件也是能读取的

package com.wei.io.study;

import java.io.FileInputStream;
import java.io.FileOutputStream;
import java.io.IOException;


public class ByteReadAndWriteDemo {
    public static void main(String[] args) throws Exception {
        String src = "C:\IDEA\mystudy\file-study\src\main\resources\mytest.txt";
        String dist = "C:\IDEA\mystudy\file-study\src\main\resources\myOuttest.txt";
        try (
                // 1、方式1
                FileInputStream fis = new FileInputStream(src);
                // 2、方式2
                //BufferedInputStream bis = new BufferedInputStream(new FileInputStream(src));
                //方式1
                FileOutputStream fos = new FileOutputStream(dist);
                //方式2
                //BufferedOutputStream bos = new BufferedOutputStream(new FileOutputStream(dist));
        ) {
            //长度自定义,读写速度跟硬盘有关，机械硬盘一般设置为1024，固态硬盘可以设为4096
            byte[] buffer = new byte[5];
            int len;
            while ((len = fis.read(buffer)) != -1) {
                System.out.println(new String(buffer, 0, len));
                // 读取到多少长度就写多少长度，避免出现乱码，避免直接使用write();
                fos.write(buffer, 0, len);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}

• 字符流是从字节流上延伸出来为了方便对字符的读取而诞生，只能读取纯文本文件
• 常见应用场景：

1. 从文本读取配置文件内容，用于程序里使用

package com.wei.io.study;

import java.io.*;

public class BufferWriteDemo {
    public static void main(String[] args) throws Exception {
        try (
                BufferedReader bufferedReader = new BufferedReader(new FileReader("C:\IDEA\mystudy\file-study\src\main\resources\mytest.txt"));
                BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter("C:\IDEA\mystudy\file-study\src\main\resources\mytestWrite.txt"));
        ) {
            // 长度自定义
            char[] buffer = new char[3];
            int len;
            StringBuilder builder = new StringBuilder();
            while ((len = bufferedReader.read(buffer)) != -1) {
                builder.append(new String(buffer,0,len));
                // 读取到多少写多少
                bufferedWriter.write(buffer, 0, len);
            }
            System.out.println(builder.toString());
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}