package com.sgcc;

import java.io.*;
import java.text.DecimalFormat;
import java.util.ArrayList;
import java.util.List;
import java.util.Random;

public class Main {
        public static String generateMixedString(int length) {
        Random random = new Random();
        StringBuilder sb = new StringBuilder(length);
        for (int i = 0; i < length; i++) {
            // 生成隨機(jī)數(shù)，當(dāng)生成的數(shù)字為0時，表示生成字母,生成數(shù)字為1時，表示生成數(shù)字；
            int type = random.nextInt(2);
            if (type == 0) {
                // 生成隨機(jī)字母（小寫）
                char letter = (char) (random.nextInt(26) + 'a');
                sb.append(letter);
            } else {
                // 生成隨機(jī)數(shù)字
                char digit = (char) (random.nextInt(10) + '0');
                sb.append(digit);
            }
        }

        return sb.toString().toUpperCase();
    }
    
    public static void main(String[] args) {
    //示例一： 生成5個長度，隨機(jī)字符串
    Main  m = new Main();
    String result =  m.generateMixedString(5);
    System.out.println(result);
    System.out.println("------------------------------------");

    //示例二： 生成18為長度不重復(fù)字符串，前6位為隨機(jī)字母和數(shù)字，后12位為數(shù)字序列
    int  limitNum = 10;
    DecimalFormat df = new DecimalFormat("000000000000");
    StringBuffer  stringBuffer = new StringBuffer();
    for (int i=0 ;i < limitNum;i++){
        stringBuffer.append(generateMixedString(6) + df.format(i)).append("\n");
    }

    //示例三：將數(shù)據(jù)寫入到文件
    String filePath = "result.txt";
    try (BufferedWriter writer = new BufferedWriter(new FileWriter(filePath))) {
        writer.write(stringBuffer.toString());
    } catch (IOException e) {
        e.printStackTrace();
    }

    //示例四：讀取文件
    final String CHARSET_NAME = "UTF-8";
    List<String> content = new ArrayList<>();
    try (BufferedReader br = new BufferedReader(new InputStreamReader(new FileInputStream(filePath), CHARSET_NAME))) {
        String line;
        while ((line = br.readLine()) != null) {
            content.add(line);
        }
    } catch (Exception e) {
        e.printStackTrace();
    }

//  輸出list中每一行的內(nèi)容
//    content.forEach(System.out::println);
//  根據(jù)下表獲取List每一行的內(nèi)容
    for (int i=0;i<content.size();i++){
        System.out.println(content.get(i));
    }


    }
}