import java.io.*;
public class Main {
    public static void main(String[] args) {
        // 使用 FileReader 讀取文件
        try (FileReader reader = new FileReader("D:\\a.txt")) {
            int data;
            while ((data = reader.read()) != -1) {
                System.out.print((char) data); // 逐個(gè)字符讀取
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 使用 InputStreamReader 讀取文件 
        try (InputStreamReader reader = new InputStreamReader(new FileInputStream("D:\\a.txt"), "UTF-8")) {
            int data;
            while ((data = reader.read()) != -1) {
                System.out.print((char) data);
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
        // 使用 BufferedReader 按行讀取文件
        try (BufferedReader br = new BufferedReader(new FileReader("D:\\a.txt"))) {
            String line;
            while ((line = br.readLine()) != null) {
                System.out.println(line); // 逐行讀取
            }
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

import java.io.*;
public class Main {
    public static void main(String[] args) {
        // 使用 FileWriter 寫(xiě)入文件
        try{
            FileWriter writer = new FileWriter("output.txt");
            writer.write("Hello, World!"); // 寫(xiě)入字符串
            writer.write("\nThis is a new line."); // 寫(xiě)入換行符
            writer.close();  //這個(gè)很重要沒(méi)有這個(gè)數(shù)據(jù)寫(xiě)入不進(jìn)去
        } catch (IOException e) {
            e.printStackTrace();
        }
        try {
            OutputStreamWriter writer = new OutputStreamWriter(new FileOutputStream("output.txt"));
            writer.write("Hello, World!"); // 寫(xiě)入字符串
            writer.write("\nThis is a new line."); // 寫(xiě)入換行符
            writer.close();  //這個(gè)很重要沒(méi)有這個(gè)數(shù)據(jù)寫(xiě)入不進(jìn)去
        }catch (IOException e){
            e.printStackTrace();
        }
        // 使用 BufferedWriter 按行寫(xiě)入文件
        try (BufferedWriter bw = new BufferedWriter(new FileWriter("output.txt"))) {
            bw.write("Hello, World!"); // 寫(xiě)入字符串
            bw.newLine(); // 寫(xiě)入換行符
            bw.write("This is a new line."); // 寫(xiě)入另一行
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
}

// 1. 寫(xiě)入單個(gè)字符
writer.write('H');
// 2. 寫(xiě)入字符數(shù)組
char[] array = {'e', 'l', 'l', 'o'};
 writer.write(array);
// 3. 寫(xiě)入字符數(shù)組的一部分
writer.write(array, 1, 2); // 寫(xiě)入 "ll"
// 4. 寫(xiě)入字符串
writer.write(", World!");
// 5. 寫(xiě)入字符串的一部分
String str = "\nThis is Java IO.";
writer.write(str, 0, 11); // 寫(xiě)入 "This is Java"

import java.io.*;
public class FileInputStreamTest {
    public static void main(String[] args)  {
        //定義輸入流
        FileInputStream fis =null;
        try {
            //1、創(chuàng)建文件對(duì)象
            File file = new File("D:\\IO\\hello.txt");
            //2、創(chuàng)建輸入流對(duì)象
            fis = new FileInputStream(file);
            //用定義字節(jié)數(shù)組，作為裝字節(jié)數(shù)據(jù)的容器
            byte[] buffer =new byte[5];
            int len;//記錄每次讀取的字節(jié)個(gè)數(shù)
            System.out.println(fis.read(buffer));
            while ((len=fis.read(buffer))!=-1){
                //轉(zhuǎn)成String型，否則輸出ASCII碼
                String str=new String(buffer,0,len);
                System.out.println(str);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //釋放資源
            try {
                fis.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}

import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
public class FileOutputStreamTest {
    public static void main (String[] args)  {
        //定義字節(jié)輸出流
        FileOutputStream fos =null;
        try {
            //1、創(chuàng)建文件對(duì)象
            File file = new File("D:\\IO\\hello.txt");
            //2、創(chuàng)建輸出流對(duì)象
            fos = new FileOutputStream(file);
            fos.write(97);
            //后面的 \r\n表示回車換行
            fos.write("中國(guó)人!\r\n".getBytes());
            //從索引2開(kāi)始輸出4個(gè)字節(jié)
            fos.write("ABCDEFGH".getBytes(),2,4);
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            //釋放資源
            try {
                fos.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
}