package demo1;

import java.io.File;

import java.io.IOException;

import java.io.RandomAccessFile;

import java.util.Scanner;

public class DateDemo {

/*

* 用RandomAccessFile 模仿数据库写法

* */

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

// TODO Auto-generated method stub

Scanner in = new Scanner(System.in);

RandomAccessFile raf = new RandomAccessFile(new File("./date.txt"),"rw");

// 各个 信息占空间是固定值

// 姓名 20 年龄 10 联系方式20 地址 60

for (int i = 0; i < 3; i++) {

System.out.println("请输入第"+(i+1)+"学生的姓名");

StringBuilder strb_Name = new StringBuilder(in.nextLine());

strb_Name = DateDemo.dealString(strb_Name, 20);

System.out.println("请输入第"+(i+1)+"学生的年龄");

StringBuilder strb_Age = new StringBuilder(in.nextLine());

strb_Age = DateDemo.dealString(strb_Age, 10);

System.out.println("请输入第"+(i+1)+"学生的联系方式");

StringBuilder strb_Tel = new StringBuilder(in.nextLine());

strb_Tel = DateDemo.dealString(strb_Tel, 20);

System.out.println("请输入第"+(i+1)+"学生的地址");

StringBuilder strb_Addr = new StringBuilder(in.nextLine());

strb_Addr = DateDemo.dealString(strb_Addr, 60);

strb_Name.append(strb_Age).append(strb_Tel).append(strb_Addr).append("\r\n");

raf.write((strb_Name+"").getBytes());

strb_Name.delete(0, strb_Name.length());

}

System.out.println("接下载修改第二名同学的电话和地址信息");

System.out.println("请输入电话");

StringBuilder strb_Tel = new StringBuilder(in.nextLine());

strb_Tel = DateDemo.dealString(strb_Tel, 20);

raf.seek(112+30);

raf.write(strb_Tel.toString().getBytes());

System.out.println("请输入地址");

StringBuilder strb_Addr = new StringBuilder(in.nextLine());

strb_Addr = DateDemo.dealString(strb_Addr, 60);

raf.seek(112+30+20);

raf.write(strb_Addr.toString().getBytes());

raf.close();

in.close();

}

//处理输入的字符 空间没有沾满的 用空格代替

public static StringBuilder dealString(StringBuilder strb , int num ) {

byte[] b = (""+strb).getBytes();

for (int i = 0; i < num - b.length; i++) {

strb.append(" ");

}

return strb;

}

}