java.nio.file.Files

public static boolean isExecutable(Path path) 
public static boolean isRegularFile(Path path, LinkOption... options) 
public static boolean isDirectory(Path path, LinkOption... options) 
public static boolean isSymbolicLink(Path path) 



boolean exist = Files.exists(Paths.get(path));
boolean notExist = Files.notExists(Paths.get(path));

Files.delete(Paths.get(path));
Files.deleteIfExists(Paths.get(path));

NoSuchFileException
DirectoryNotEmptyException
   
Files.createDirectories(Paths.get(path));
Files.createFile(Paths.get(file));

List< String> list = new ArrayList< >();
list.add("this is title");
list.add("this is content");
Files.write(Paths.get(path), list, StandardOpenOption.APPEND, StandardOpenOption.CREATE);
Files.write(Paths.get(path), "this is context".getBytes(), StandardOpenOption.APPEND, StandardOpenOption.CREATE);


StandardOpenOption.APPEND 追加 
StandardOpenOption.CREATE 文件不存在则创建
默认使用UTF-8 


List< String> list1 = Files.readAllLines(Paths.get("/path/file.txt"), StandardCharsets.UTF_8);
List< String> list2 = Files.readAllLines(Paths.get("/path/file.txt"), Charset.forName("UTF-8"));
List< String> list3 = Files.readAllLines(Paths.get("/path/file.txt"), Charset.defaultCharset());


按行读取
String file = "/path/file.txt";
try (InputStreamReader reader = new InputStreamReader(new FileInputStream(file), Charset.forName("UTF-8"));
    BufferedReader br = new BufferedReader(reader);) {
    String line;
    while ((line = br.readLine()) != null) {
        System.out.println(line);
    }
} catch (Exception e) {
    e.printStackTrace();
}

递归删除文件及文件夹
String path = "/path/dir";
Files.walk(Paths.get(path))
        .sorted(Comparator.reverseOrder())
        .map(Path::toFile)
        .forEach(File::delete);

Files.walkFileTree 遍历删除

String path = "/path/dir";
Files.walkFileTree(Paths.get(path), new SimpleFileVisitor() {
            // 访问文件时
            @Override
            public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                Files.delete(file);
                System.out.printf("文件被删除 : %s%n", file);
                return FileVisitResult.CONTINUE;
            }

            // 访问子目录前
            @Override
            public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
                System.out.printf("正在访问目录 : %s%n", dir);
                return FileVisitResult.CONTINUE;
            }

            // 访问目录之后
            @Override
            public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                Files.delete(dir);
                System.out.printf("文件夹被删除: %s%n", dir);
                return FileVisitResult.CONTINUE;
            }

            // 访问失败时 
            @Override
            public FileVisitResult visitFileFailed(Path file, IOException exc) throws IOException {
                System.out.println("visitFileFailed "+exc);
                return super.visitFileFailed(file, exc);
            }

        }
);