FileReader 和 FileWriter 是字符流，即按照字符来操作 I/O 。

示例代码

import java.io.FileReader;
import java.io.IOException;
public class Main {
    public static void main(String[] args) {
//        readFile01();
        readFile02();
    }
    // 一次读取 1 个字符
    public static void readFile01() {
        String path = "./hello.txt";
        FileReader freader = null;
        int temp;
        try {
            freader = new FileReader(path);
            while ((temp = freader.read()) != -1) {
                System.out.print((char) temp);
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭流
            try {
                freader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
    // 一次读取 1024 个字符
    public static void readFile02() {
        String path = "./hello.txt";
        FileReader freader = null;
        int readLen = 0;
        char[] buffer = new char[1024];
        try {
            freader = new FileReader(path);
            while ((readLen = freader.read(buffer)) != -1) {
                System.out.print(new String(buffer, 0, readLen));
            }
        } catch (IOException e) {
            e.printStackTrace();
        } finally {
            // 关闭流
            try {
                freader.close();
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
    }
}