java File

1、静态方法

// 1.路径与路径之间分隔符 ;
System.out.println(File.pathSeparator);
// 2.路径本身的分隔符 /
System.out.println(File.separator);

2、构造方法

// 1.newFile(String)
File file = new File("E:\\data\\1.jpg");
System.out.println("file = " + file);
// 2.newFile(String, String)
File file1 = new File("E:\\data", "2.jpg");
System.out.println("file1 = " + file1);
// 3.newFile(File, String)
File file2 = new File("E:\\data");
File file3 = new File(file2, "3.jpg");
System.out.println("file3 = " + file3);

3、获取方法

// 1.获取绝度路径
File file = new File("E:\\data\\4.jpg");
String absolutePath = file.getAbsolutePath();
System.out.println("absolutePath = " + absolutePath);
// 2.获取文件前的路径
String path = file.getParent();
System.out.println("path = " + path);
// 3.获取文件名称
String name = file.getName();
System.out.println("name = " + name);

获取文件字节数

// length
File file2 = new File("E:\\data\\1.txt");
long length = file2.length();
System.out.println("length = " + length);

4、创建方法

注意：创建文件和创建文件夹，无论是文件还是文件夹需要再构造方法中体现

// 1.createNewFile，创建文件，file路径中
File file = new File("E:\\data\\1.txt");
boolean newFile = file.createNewFile();
System.out.println("newFile = " + newFile);
// 2.创建文件夹
File file1 = new File("E:\\data\\aa\\bb\\cc");
boolean mkdirs = file1.mkdirs();
System.out.println("mkdirs = " + mkdirs);

5、删除方法

注意：删除文件夹，只能删除空的，且删除的文件或文件夹，体现在构造方法

// 1.删除文件夹，只能删除空的
File file = new File("E:\\data\\aa\\bb\\cc");
boolean delete = file.delete();
System.out.println("delete = " + delete);
// 2.删除文件
File file1 = new File("E:\\data\\1.txt");
boolean delete1 = file1.delete();
System.out.println("delete1 = " + delete1);

6、判断方法

File file = new File("E:\\data\\aa\\bb");
// 1.isDirectory,判断是否是目录(文件夹)
boolean directory = file.isDirectory();
System.out.println("directory = " + directory);
// 2.isFile,判断是否是文件
boolean file1 = file.isFile();
System.out.println("file1 = " + file1);
// 3.exists, 判断是否存在
boolean exists = file.exists();
System.out.println("exists = " + exists);

7、遍历方法

File file = new File("E:\\data");
// 1.listFiles 遍历 完整路径
File[] files = file.listFiles();
for (File file1 : files) {
    System.out.println(file1);
}
System.out.println("===================================");
// 2. list 遍历不是完整 路径
String[] list = file.list();
for (String s : list) {
    System.out.println(s);
}