Java 编写一个带缓存的对文本文件进行读写操作的程序。 (1)可以读取不同位置的信息 (2)可以把数据写入到不同的位置 例如：创建一个学生类(含姓名，性别，年龄等信息)，从键盘上输入学生信息，把学 生对象保存在指定文本文件中的指定位置。从文本文件中读取特定学生信息。 实现学生信息的增加、删除、修改、插入等操作。

以下是一个基本的带缓存的对文本文件进行读写操作的Java程序。你可以根据需要进行修改和扩展。

import java.io.*;

class Student implements Serializable {
    private static final long serialVersionUID = 1L;
    String name;
    String gender;
    int age;

    public Student(String name, String gender, int age) {
        this.name = name;
        this.gender = gender;
        this.age = age;
    }

    public String toString() {
        return name + "," + gender + "," + age;
    }
}

class FileCache {
    private RandomAccessFile file;
    private int cacheSize;
    private byte[] buffer;
    private long start = 0;
    private long end = 0;
    private long pointer = 0;

    public FileCache(String filename, int cacheSize) throws IOException {
        file = new RandomAccessFile(filename, "rw");
        this.cacheSize = cacheSize;
        buffer = new byte[cacheSize];
    }

    public void write(long pos, byte[] data) throws IOException {
        if (pos < end && pos + data.length > end) {
            flush();
        }
        if (pos >= end) {
            start = pos;
            end = start + cacheSize;
            file.seek(start);
            pointer = start;
        }
        file.write(data);
    }

    public byte[] read(long pos, int len) throws IOException {
        if (pos < start || pos + len > end) {
            start = pos;
            end = start + cacheSize;
            file.seek(start);
            pointer = start;
            int n = file.read(buffer);
            if (n < cacheSize) {
                end = start + n;
            }
        }
        int off = (int) (pos - start);
        byte[] data = new byte[len];
        int n = Math.min(len, cacheSize - off);
        System.arraycopy(buffer, off, data, 0, n);
        pointer = pos + n;
        return data;
    }

    public void flush() throws IOException {
        file.seek(start);
        file.write(buffer, 0, (int) (end - start));
        start = end;
        end = start + cacheSize;
        pointer = start;
    }

    public void close() throws IOException {
        flush();
        file.close();
    }

    public long getPointer() {
        return pointer;
    }
}

public class FileDemo {
    private static final int CACHE_SIZE = 1024 * 1024; // 1MB

    public static void main(String[] args) throws IOException, ClassNotFoundException {
        FileCache cache = new FileCache("students.txt", CACHE_SIZE);
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        while (true) {
            System.out.println("请选择操作：1.增加 2.删除 3.修改 4.插入 5.查找 6.退出");
            int choice = Integer.parseInt(br.readLine());
            switch (choice) {
                case 1:
                    addStudent(cache, br);
                    break;
                case 2:
                    deleteStudent(cache, br);
                    break;
                case 3:
                    updateStudent(cache, br);
                    break;
                case 4:
                    insertStudent(cache, br);
                    break;
                case 5:
                    findStudent(cache, br);
                    break;
                case 6:
                    cache.close();
                    System.exit(0);
                    break;
                default:
                    System.out.println("无效的选择！");
            }
        }
    }

    private static void addStudent(FileCache cache, BufferedReader br) throws IOException {
        System.out.println("请输入学生信息：姓名，性别，年龄");
        String[] fields = br.readLine().split(",");
        Student s = new Student(fields[0], fields[1], Integer.parseInt(fields[2]));
        byte[] data = s.toString().getBytes();
        cache.write(cache.getPointer(), data);
        System.out.println("添加成功！");
    }

    private static void deleteStudent(FileCache cache, BufferedReader br) throws IOException {
        System.out.println("请输入要删除的学生姓名：");
        String name = br.readLine();
        long pos = 0;
        boolean found = false;
        while (pos < cache.getPointer() && !found) {
            byte[] data = cache.read(pos, CACHE_SIZE);
            String[] lines = new String(data).split("\n");
            for (String line : lines) {
                String[] fields = line.split(",");
                if (fields[0].equals(name)) {
                    found = true;
                    break;
                }
                pos += line.length() + 1;
            }
        }
        if (found) {
            pos -= line.length() + 1;
            cache.write(pos, new byte[line.length()]);
            System.out.println("删除成功！");
        } else {
            System.out.println("未找到指定学生！");
        }
    }

    private static void updateStudent(FileCache cache, BufferedReader br) throws IOException {
        System.out.println("请输入要修改的学生姓名：");
        String name = br.readLine();
        long pos = 0;
        boolean found = false;
        while (pos < cache.getPointer() && !found) {
            byte[] data = cache.read(pos, CACHE_SIZE);
            String[] lines = new String(data).split("\n");
            for (String line : lines) {
                String[] fields = line.split(",");
                if (fields[0].equals(name)) {
                    found = true;
                    System.out.println("请输入修改后的学生信息：姓名，性别，年龄");
                    String[] newFields = br.readLine().split(",");
                    Student s = new Student(newFields[0], newFields[1], Integer.parseInt(newFields[2]));
                    byte[] newData = s.toString().getBytes();
                    cache.write(pos, newData);
                    break;
                }
                pos += line.length() + 1;
            }
        }
        if (found) {
            System.out.println("修改成功！");
        } else {
            System.out.println("未找到指定学生！");
        }
    }

    private static void insertStudent(FileCache cache, BufferedReader br) throws IOException {
        System.out.println("请输入要插入的位置（从0开始）：");
        long pos = Long.parseLong(br.readLine());
        byte[] data = cache.read(pos, CACHE_SIZE);
        String[] lines = new String(data).split("\n");
        int len = 0;
        for (String line : lines) {
            len += line.length() + 1;
        }
        System.out.println("请输入要插入的学生信息：姓名，性别，年龄");
        String[] fields = br.readLine().split(",");
        Student s = new Student(fields[0], fields[1], Integer.parseInt(fields[2]));
        byte[] newData = (s.toString() + "\n").getBytes();
        cache.write(pos, newData);
        cache.write(pos + newData.length, data, 0, len);
        System.out.println("插入成功！");
    }

    private static void findStudent(FileCache cache, BufferedReader br) throws IOException, ClassNotFoundException {
        System.out.println("请输入要查找的学生姓名：");
        String name = br.readLine();
        long pos = 0;
        boolean found = false;
        while (pos < cache.getPointer() && !found) {
            byte[] data = cache.read(pos, CACHE_SIZE);
            String[] lines = new String(data).split("\n");
            for (String line : lines) {
                String[] fields = line.split(",");
                if (fields[0].equals(name)) {
                    found = true;
                    Student s = new Student(fields[0], fields[1], Integer.parseInt(fields[2]));
                    System.out.println("查找结果：" + s.toString());
                    break;
                }
                pos += line.length() + 1;
            }
        }
        if (!found) {
            System.out.println("未找到指定学生！");
        }
    }
}

这个程序使用了随机访问文件(RandomAccessFile)和缓存技术，可以对文本文件进行读写操作，并支持对学生信息的增加、删除、修改、插入和查找。注意，为了能够将学生对象保存到文件中，需要实现Serializable接口。