J2SE 8的输入输出--Path/Paths File/Files; FileSystems 类的用法

Path的简单用法

//1. Path 正常用法
Path path = Paths.get("src/main/resource/zip");
logger.debug(path.toRealPath());
logger.debug(path.toAbsolutePath());
logger.debug(path.getFileName());
logger.debug(path.getParent());
logger.debug(path.getNameCount());
logger.debug(path.getRoot());

path = FileSystems.getDefault().getPath("src/main/resource/zip");
logger.debug(path.toRealPath());
logger.debug(path.toAbsolutePath());
logger.debug(path.getFileName());
logger.debug(path.getParent());
logger.debug(path.getNameCount());
logger.debug(path.getRoot());

//2. Path get(String first, String... more)	用默认的文件系统路径分隔符连接元素
Path path2 = Paths.get("src/main", "resource/zip");
logger.debug(path2.toRealPath());
logger.debug(path2.toAbsolutePath());
logger.debug(path2.getFileName());
logger.debug(path2.getParent());
logger.debug(path2.getNameCount());
logger.debug(path2.getRoot());

//3. resolve(other)
//(1) other 不是绝对路径, 连接this父路径和other
Path mainPath = Paths.get("/main/");
Path completePath = mainPath.resolve("/zip/Json.rar");
logger.debug(completePath.toAbsolutePath());

//(2) other 是绝对路径, 使用other
completePath = mainPath.resolve("D:/AbsolutePath/zip/Json.rar");
logger.debug(completePath.toAbsolutePath());

//4. resolveSibling(other)	得到兄弟路径
//(1) other 不是绝对路径, 连接this父路径和other
mainPath = Paths.get("/main/");
completePath = mainPath.resolveSibling("/zip");
logger.debug(completePath.toAbsolutePath());

//(2) other 是绝对路径, 使用other
completePath = mainPath.resolveSibling("D:/AbsolutePath/zip/Json.rar");
logger.debug(completePath.toAbsolutePath());

//5. relativize()	对this解析, 得到相对于other的 相对路径
mainPath = Paths.get("/main/");
Path relativize = mainPath.relativize(Paths.get("/main/AA/BB/CC"));
logger.debug(relativize);

//6. normalize()	移除冗余的..和.
Path normalize = Paths.get("/home/cay/../fred/./myprog").normalize();
logger.debug(normalize);

//7. path to file
System.out.println(mainPath.toFile());

//8. file to path
System.out.println(mainPath.toFile().toPath());

Paths辅助类用法

File的简单用法

// 创建文件:
boolean result = new File("textFile.txt").createNewFile();

// 文件重命名:
result = new File("textFile.txt").renameTo(new File("newTextFile.txt"));

// 删除文件:
new File("somefile.txt").delete();

// 改变文件属性:
File f = new File("somefile.txt");
f.setReadOnly(); // making the file read only
f.setLastModified(new Date().getTime());

// 获取文件大小:
long length = new File("somefile.txt").length();

// 判断文件是否存在:
boolean status = new File("somefile.txt").exists();

// 移动文件:
boolean success = new File("somefile.txt").renameTo(new File(new File("directoryName"), "new Name"));

// 获取绝对路径:
File absPath = new File("somefile.txt").getAbsoluteFile();

// 判断是文件还是目录:
boolean isDirectory = new File("somefile.txt").isDirectory();
System.out.println(isDirectory); // false

// 列举目录下文件:
String[] fileResult = new File("users/ege").list();

// 创建目录:
boolean mkdirResult = new File("users/ege").mkdir();

//过滤文件
File file = new File("E:\\core");
String[] list = file.list(new FilenameFilter() {
	@Override
	public boolean accept(File dir, String name) {
		return name.endsWith(".pdf");
	}
});

for (String pdfFile : list) {
	System.out.println(pdfFile);
}

//文件监视器
watchService("E:\\test");

//异步通信
//Asynchronous

Files辅助类用法

//1. 读写文件
//(1) Files.readAllBytes()
String string = new String(Files.readAllBytes(Paths.get("E:\\111.txt")), StandardCharsets.UTF_8);
System.out.println(string);
System.out.println();

//(2) Files.readAllLines()
List<String> strings = Files.readAllLines(Paths.get("E:\\111.txt"), StandardCharsets.UTF_8);
System.out.println(strings);
System.out.println();

//(3) Files.write()
//向文件覆写内容
Files.write(Paths.get("E:\\111.txt"), "File Write Test1".getBytes(StandardCharsets.UTF_8));

//向文件追加内容
Files.write(Paths.get("E:\\111.txt"), "File Write Test2".getBytes(StandardCharsets.UTF_8), StandardOpenOption.APPEND);

//从另一个文件中拷贝文件(处理的文件比较大, 需要用Buffered等)	//java.nio.charset.MalformedInputException: Input length = 1==>GBK
Files.write(Paths.get("E:\\111.txt"), Files.readAllLines(Paths.get("E:\\java.txt"), Charset.forName("GBK")), StandardOpenOption.APPEND);

//(4) Files.newInputStream()
try(InputStream newInputStream = Files.newInputStream(Paths.get("E:\\111.txt"));){
	byte[] b = new byte[1024];
	int hasRead = 0;
	while ((hasRead = newInputStream.read(b)) > 0) {
		System.out.print(new String(b, 0, hasRead));
	}
}

//(5) Files.newOutputStream()
try(OutputStream newOutputStream = Files.newOutputStream(Paths.get("E:\\111.txt"));){
	newOutputStream.write("第一期面授培训大纲.pdf".getBytes());
	newOutputStream.write("2017.07体检报告.pdf".getBytes());
	newOutputStream.write("csdn下载文档".getBytes());
}

//(6) Files.newBufferedReader()
try(BufferedReader newBufferedReader = Files.newBufferedReader(Paths.get("E:\\111.txt"));){
	newBufferedReader.lines().forEach(n->System.out.println(n));
}

//(7) Files.newBufferedWriter()
try(BufferedWriter newBufferedWriter = Files.newBufferedWriter(Paths.get("E:\\111.txt"));){
	newBufferedWriter.write("时寒冰说：未来二十年，经济大趋势（未来篇） - 时寒冰");
	newBufferedWriter.write("时寒冰说：未来二十年，经济大趋势（现实篇）");
}

//2. 创建文件
//(1) 创建目录及文件
Path pathA = Paths.get("E:\\FilesTest\\A\\111.txt");
if(Files.notExists(pathA)){
	Files.createDirectories(pathA.getParent());		//创建中间目录

	//windows下不支持PosixFilePermission来指定rwx权限。
//			Set<PosixFilePermission> perms = PosixFilePermissions.fromString("rw-rw-rw-");
//			FileAttribute<Set<PosixFilePermission>> attrs = PosixFilePermissions.asFileAttribute(perms);

	Files.createFile(Paths.get("E:\\FilesTest\\A\\111.txt"));
}
System.out.println();

//(2) 创建临时文件
//建立临时目录
Path tempDirectory = Files.createTempDirectory("temp");
System.out.println(tempDirectory.toAbsolutePath());
Files.deleteIfExists(tempDirectory);
System.out.println();

//建立临时文件
Path createTempFile = Files.createTempFile("temp", ".txt");
System.out.println(createTempFile.toAbsolutePath());
Files.deleteIfExists(createTempFile);
System.out.println();

//3. 复制文件
Files.copy(Paths.get("E:\\111.txt"), pathA, StandardCopyOption.REPLACE_EXISTING, StandardCopyOption.COPY_ATTRIBUTES);

Files.copy(pathA, System.out);
System.out.println();

//		Path tempPath = Paths.get("E:\\temp.txt");
//		Files.copy(System.in, tempPath);
//		Files.copy(tempPath, System.out);

//4. 移动文件
Path pathB = Paths.get("E:\\FilesTest\\B\\222.txt");
Files.createDirectories(pathB.getParent());
Files.move(pathA, pathB, StandardCopyOption.ATOMIC_MOVE);

//5. 文件属性
//(1) Files
Path path = Paths.get("E:\\java.txt");
System.out.println(Files.size(path));
System.out.println(Files.isHidden(path));
System.out.println(Files.isReadable(path));
System.out.println(Files.isWritable(path));
System.out.println(Files.isExecutable(path));
System.out.println(Files.isRegularFile(path));
System.out.println(Files.isDirectory(path));
System.out.println(Files.isSymbolicLink(path));
System.out.println(Files.isSameFile(path, path));
System.out.println();

//Reset Attributes
//		PosixFileAttributes readAttributes = Files.readAttributes(source, PosixFileAttributes.class);
//		Set<PosixFilePermission> permissions = readAttributes.permissions();
//		permissions.clear();
//
//		String owner = readAttributes.owner().getName();
//		String perms = PosixFilePermissions.toString(permissions);
//		permissions.add(PosixFilePermission.OWNER_READ);
//		permissions.add(PosixFilePermission.GROUP_READ);
//		permissions.add(PosixFilePermission.OTHERS_READ);
//		permissions.add(PosixFilePermission.OWNER_READ);
//
//		Files.setPosixFilePermissions(source, permissions);

//(2) BasicFileAttributes
BasicFileAttributes fileAttributes = Files.readAttributes(path, BasicFileAttributes.class, LinkOption.NOFOLLOW_LINKS);
System.out.println(fileAttributes.creationTime());
System.out.println(fileAttributes.lastAccessTime());
System.out.println(fileAttributes.lastModifiedTime());
System.out.println(fileAttributes.isRegularFile());
System.out.println(fileAttributes.isDirectory());
System.out.println(fileAttributes.isSymbolicLink());
System.out.println(fileAttributes.size());
System.out.println(fileAttributes.fileKey());
System.out.println();

//6. 删除文件
//		Files.deleteIfExists(pathA);
//		Files.deleteIfExists(pathB);

//7. 访问目录中的项
//(1) Files.list()		注意不是Files.lines()		注意list()方法不处理子目录
Path listPath = Paths.get("E:\\core");
Stream<Path> entries = Files.list(listPath);
entries.forEach(n->System.out.println(n.toAbsolutePath()));
System.out.println();

//(2) Files.walk()		walk()可以处理子目录, 也可以设置最大访问深度
Stream<Path> walkEntries = Files.walk(listPath, FileVisitOption.FOLLOW_LINKS);
walkEntries.forEach(n->System.out.println(n.toAbsolutePath()));
System.out.println();

//8. 过滤文件
//(1) Files.newDirectoryStream()  	the glob pattern
DirectoryStream<Path> newDirectoryStream = Files.newDirectoryStream(listPath, "*.doc");
newDirectoryStream.forEach(n->System.out.println(n.toAbsolutePath()));
System.out.println();

//(2) Files.walkFileTree()
Files.walkFileTree(listPath, new FindDocisitor());
System.out.println();

//(3) 利用FileVisitor接口, 在删除所有文件后, 移除对应目录
Files.walkFileTree(Paths.get("E:\\FilesTest"), new SimpleFileVisitor<Path>(){
	public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
		Files.delete(file);
		return FileVisitResult.CONTINUE;
	};

	public FileVisitResult postVisitDirectory(Path dir, IOException exc) throws IOException {
		if(null!=exc){
			throw exc;
		}

		Files.delete(dir);
		return FileVisitResult.CONTINUE;
	};
});

//9. 

FileSystems 辅助类用法

处理Zip文件

//1. 建立文件系统
FileSystem fileSystem = FileSystems.newFileSystem(Paths.get("E:\\core.zip"), null);

//2. 从zip文件中复制出任意文件
Files.copy(fileSystem.getPath("/111.txt"), Paths.get("E:\\888.txt"));

//3. 遍历zip文件系统
Files.walkFileTree(fileSystem.getPath("/"), new SimpleFileVisitor<Path>(){
	@Override
	public FileVisitResult visitFile(Path file, BasicFileAttributes attrs) throws IOException {
		System.out.println(file.toAbsolutePath());
		return super.visitFile(file, attrs);
	}
});