package daily;

import java.io.*;
import java.util.Calendar;

public class test3_file {
    public static void main(String[] args) throws IOException {

        //获取系统时间
        Calendar today = Calendar.getInstance();
        int year = today.get(Calendar.YEAR);
        int month =today.get(Calendar.MONTH)+1;//注意
        int day = today.get(Calendar.DAY_OF_MONTH);
        String y = ""+year;
        String m = ""+month;
        String d = Integer.toString(day);

//        创建一个目录
        String filePath ="D:\\"+y+"\\"+m+"\\"+d+"";
        File f =new File(filePath);
        if (!f.exists()){
            f.mkdirs();
            System.out.println("创建完成！");
        }
        else{
            System.out.println("该目录已经存在！");
        }
//        向文件中存入数据
//        自动创建文件
        File file = new File(filePath,"test.txt");
        Writer writer = new FileWriter(file);//此处需要抛出异常
        writer.write("你好！世界！！");
        writer.close();

//        从文件中读取数据
        File file2 = new File(filePath,"test.txt");
        Reader reader = new FileReader(file2);
        char [] c = new char[1024];
         int len = reader.read(c);
         String str  = "";
         while(len!=-1){

             str=new String(c,0,len);
             len = reader.read(c);
         }
        System.out.println(str);
    }
}