JAVA 探究NIO

　　Path get(String pathname,String ...more)
　　Path get(URI uri)

        Path path = Paths.get("./nio/src/1.txt");
        System.out.println("自身路径："+path.toString());//输出.\nio\src\1.txt
        System.out.println("文件或目录名称："+path.getFileName());//输出1.txt
        System.out.println("路径元素数量："+path.getNameCount());//输出4
        System.out.println("路径中第3截："+path.getName(2));//输出src
        System.out.println("父目录的路径"+path.getParent());//输出.\nio\src
        System.out.println(path.getRoot());//输出null
        System.out.println("是否绝对路径："+path.isAbsolute());//输出false

        Path p = path.toAbsolutePath();//返回与该路径等价的绝对路径
        System.out.println("看看我这个是不是绝对路径："+p.toString());//输出E:\JAVA\java_learning\.\nio\src\1.txt

        File file = path.toFile();//从该路径创建一个File对象
        System.out.println("文件是否存在："+file.exists());//false

        Path path1 = file.toPath();//再把File对象转成Path对象
        System.out.println("是不是同一个对象："+path1.equals(path));//输出true

        try(FileChannel seekableByteChannel = (FileChannel) Files.newByteChannel(Paths.get("./nio/src/2.txt"))){
            ByteBuffer buffer = ByteBuffer.allocate(5);//指定缓冲区大小
            int count = seekableByteChannel.read(buffer);//将文件中的数据读取到缓冲区
            buffer.rewind();
            while (count > 0){
                System.out.println((char)buffer.get());//读取缓冲区中的数据
                count --;
            }
        }catch (Exception e){
            e.printStackTrace();
        }

　　MappedByteBuffer map(FileChannel.MapMode how,long begin,long size) throws IOException

        try(FileChannel fileChannel = (FileChannel) Files.newByteChannel(Paths.get("./nio/src/2.txt"))){
            long size = fileChannel.size();//获取文件字节数量
            MappedByteBuffer mappedByteBuffer = fileChannel.map(FileChannel.MapMode.READ_ONLY,0,size);
            for(int i=0;i < size; i ++){
                System.out.println((char)mappedByteBuffer.get());
            }
        }catch (Exception e){
            e.printStackTrace();
        }

        try(FileChannel seekableByteChannel = (FileChannel) Files.newByteChannel(Paths.get("./nio/src/2.txt"),StandardOpenOption.WRITE,StandardOpenOption.CREATE,StandardOpenOption.APPEND)){
            ByteBuffer buffer = ByteBuffer.allocate(5);//指定缓冲区大小
            for(int i=0;i<5;i++){
                buffer.put((byte)('A'+i));
            }
            buffer.rewind();
            seekableByteChannel.write(buffer);
        }catch (Exception e){
            e.printStackTrace();
        }

        Path path = Paths.get("./nio/src/4.txt");
        try(FileChannel fileChannel = (FileChannel) Files.newByteChannel(path,StandardOpenOption.WRITE,StandardOpenOption.READ,StandardOpenOption.CREATE)){
            MappedByteBuffer buffer = fileChannel.map(FileChannel.MapMode.READ_WRITE,0,5);
            for(int i=0;i < 5; i ++){
                buffer.put((byte) ('A'+i));
            }
        }catch (Exception e){
            e.printStackTrace();
        }

        Path path = Paths.get("./nio/src/4.txt");
        Path path2 = Paths.get("./nio/src/40.txt");
        try{
            Files.copy(path2,path, StandardCopyOption.REPLACE_EXISTING);
            //Files.move(path,path2, StandardCopyOption.REPLACE_EXISTING);
        }catch (Exception e){
            e.printStackTrace();
        }

　　static InputStream newInputStream(Path path,OpenOption... how) throws IOException

        try(BufferedInputStream inputStream = new BufferedInputStream(Files.newInputStream(Paths.get("./nio/src/2.txt")))){
            int s = inputStream.available();
            for(int i=0;i<s;i++){
                int c = inputStream.read();
                System.out.print((char) c);
            }
        }catch (Exception e){
            e.printStackTrace();
        }

        try(BufferedOutputStream outputStream = new BufferedOutputStream(Files.newOutputStream(Paths.get("./nio/src/2.txt")))){
            for(int i=0;i<26;i++){
                outputStream.write((byte)('A'+i));
            }
        }catch (Exception e){
            e.printStackTrace();
        }

        try{
            Path path = Paths.get("./nio/src/8.txt");
            String str = "今天天气不错哦\n";
            Files.write(path,str.getBytes(),StandardOpenOption.CREATE, StandardOpenOption.APPEND);
        }catch (Exception e){
            e.printStackTrace();
        }

　　static DirectoryStream<Path> newDirectoryStream(Path dir) throw IOException

        try(DirectoryStream<Path> paths = Files.newDirectoryStream(Paths.get("./nio/src"))){
            for(Path path : paths){
                System.out.println(path.getFileName());
            }
        }catch (Exception e){
            e.printStackTrace();
        }

　　static DirectoryStream<Path> newDirectoryStream(Path dir,String glob) throws IOException

        try(DirectoryStream<Path> paths = Files.newDirectoryStream(Paths.get("./nio/src"),"*.java")){
            for(Path path : paths){
                System.out.println(path.getFileName());
            }
        }catch (Exception e){
            e.printStackTrace();
        }

　　static DirectoryStream<Path> newDirectoryStream(Path dir,DirectoryStream.Filter<? super Path> filter) throws IOException

　　boolean accept(T entry) throws IOException

        String dirname = "./nio/src";
        DirectoryStream.Filter<Path> filter = (entry)->{
            if(Files.size(entry) > 25){
                return true;
            }
            return false;
        };
        try(DirectoryStream<Path> paths = Files.newDirectoryStream(Paths.get(dirname),filter)){
            for(Path path : paths){
                System.out.println(path.getFileName());
            }
        }catch (Exception e){
            e.printStackTrace();
        }

        String dir = "./nio";
        try{
            Files.walkFileTree(Paths.get(dir), new SimpleFileVisitor<Path>(){
                @Override
                public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
                    System.out.println("正在访问文件："+file);
                    return super.visitFile(file, attrs);
                }

                @Override
                public FileVisitResult preVisitDirectory(Path dir, BasicFileAttributes attrs) throws IOException {
                    System.out.println("正在访问目录："+dir);
                    return super.preVisitDirectory(dir, attrs);
                }

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

                @Override
                public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
                    System.out.println("这个目录访问结束了："+dir);
                    return super.postVisitDirectory(dir, exc);
                }
            });
        }catch (Exception e){
            e.printStackTrace();
        }

　　FileChannel channel = FileChannel.open(path);
　　FileLock lock = channel.lock() 或者 FileLock lock1 = channel.tryLock()

　　FileLock lock(long start,long size,boolean shared)
　　FileLock lock(long start,long size,boolean shared)