package bxd;

import java.io.File;

public class FileDemo {

    public static void consMethod() {
        // 将a.txt封装成File对象, 可以将已有的或者未创建的"文件或文件夹"封装成对象.
        File file1 = new File("a.txt");
        File file2 = new File("/Users/Eric/Documents/IdeaProjects/Servlet_JSP/JDBCDemo/b.txt");
        String parent = "/Users/Eric/Documents/IdeaProjects/Servlet_JSP/JDBCDemo";
        File file3 = new File(parent, "c.txt");

        /* static String    separator
                The system-dependent default name-separator character, represented as a string for convenience.
        */
        File file4 = new File(File.separator + "abc" + File.separator + "xyz.txt");

        // 会以字符串形式打印出创建File对象时传入的参数,不会改变.
        sop("file1: " + file1);
        sop("file2: " + file2);
        sop("file3: " + file3);
        sop("file4: " + file4);
    }

    public static void main(String[] args) {
        consMethod();
    }

    public static void sop(Object object) {
        System.out.println(object);
    }
}

package bxd;

import java.io.File;
import java.io.IOException;

/*
File类常见方法:
1. 创建
    boolean createNewFile()  在指定位置创建文件. 如果创建成功则返回true; 如果创建失败或文件已经存在则返回false.
                             相比较, new一个输出流对象会马上创建文件, 且遇到文件已存在时会覆盖源文件.
    boolean mkdir()          创建指定的目录
    boolean mkdirs()         创建指定的目录, 包括所有所需但不存在的父目录
2. 删除
    boolean delete()         删除失败则返回false.
    void deleteOnExit()      文件有可能正被程序访问而无法删除, 此时可以将文件设置为程序退出时删除.
*/
public class FileDemo1 {

    public static void method_1() throws IOException {
        File file = new File("file.txt");
        sop("create file.txt: " + file.createNewFile());
    }

    public static void method_2() throws IOException {
        File dir = new File("dir_abc");
        dir.mkdir();
    }

    public static void method_3() {
        File file = new File("file.txt");
        sop("delete file.txt: " + file.delete());
    }

    public static void main(String[] args) throws IOException {
        method_2();
    }

    public static void sop(Object object) {
        System.out.println(object);
    }
}

package bxd;

import java.io.File;
import java.io.IOException;

/*
File类常见方法:
3. 判断
    boolean exists()     判断文件/文件夹是否存在
    boolean canExecute() 判断文件是否可执行, 如果文件不存在也返回false
    boolean isFile()
    boolean isDirectory  判断File对象是否是文件/目录, 如果不存在也返回false
        所以判断时要注意区分: 是/否/不存在

    boolean isAbsolute() 判断File对象所对应的pathname是否是绝对路径(与文件/文件夹是否存在无关)
*/
public class FileDemo2 {

    public static void method_1() throws IOException {
        File file = new File("file.txt");
        sop("file.txt exists: " + file.exists());
        sop("file.txt canExcute: " + file.canExecute());
    }

    public static void method_2() {
        File file = new File("file.txt");
        sop("file.txt isFile: " + file.isFile());
        sop("file.txt isDirectory: " + file.isDirectory());
    }

    public static void main(String[] args) throws IOException {
        method_2();
    }

    public static void sop(Object object) {
        System.out.println(object);
    }
}