File类

引用自java中的IO整理

  • 初始化变量

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    private static final String FILENAME = "E:\\hello.txt";
    private static final String FILENAME_WITH_SEPARATOR = "E:" + File.separator + "world.txt";
    private static final String DIRECTORY_NAME = "E:" + File.separator + "hello" + File.separator + "world";
    private static final String ROOT_DIRECTORY = "E:" + File.separator;
    private static final String SUCCESS = "成功";
    private static final String FAIL = "失败";

创建一个新文件

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private static void testCreateFile() {
    File file = new File(FILENAME);
    try {
        boolean createResult = file.createNewFile();
        System.out.println("创建文件" + FILENAME + (createResult ? SUCCESS : FAIL));
    } catch (IOException e) {
        e.printStackTrace();
    }
}

File类的两个常量

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private static void fileConstants() {
    System.out.println(File.separator);
    System.out.println(File.pathSeparator);
}

创建包含File.separator的文件

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private static void testCreateFileWithSeparator() {
    File file = new File(FILENAME_WITH_SEPARATOR);
    try {
        boolean createResult = file.createNewFile();
        System.out.println("创建文件" + FILENAME_WITH_SEPARATOR + (createResult ? SUCCESS : FAIL));
    } catch (IOException e) {
        e.printStackTrace();
    }
}

删除一个文件

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private static void testDeleteFile() {
    File file = new File(FILENAME_WITH_SEPARATOR);
    if (file.exists()) {
        boolean deleteResult = file.delete();
        System.out.println("删除文件" + FILENAME_WITH_SEPARATOR + (deleteResult ? SUCCESS : FAIL));
    } else {
        System.out.println("文件不存在");
    }
}

创建一个文件夹

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private static void testCreateDirectory() {
    File directory = new File(DIRECTORY_NAME);
    boolean result = directory.mkdirs();
    System.out.println("创建文件夹" + DIRECTORY_NAME + (result ? SUCCESS : FAIL));
}

列出指定目录的全部文件（包括隐藏文件）

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private static void testList() {
    File rootDirectory = new File(ROOT_DIRECTORY);
    String[] files = rootDirectory.list();
    if (files != null) {
        Arrays.stream(files).forEach(System.out::println);
    }
}

列出指定目录完整路径的全部文件（包括隐藏文件）

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private static void testListFiles() {
    File rootDirectory = new File(ROOT_DIRECTORY);
    File[] files = rootDirectory.listFiles();
    if (files != null) {
        Arrays.stream(files).forEach(System.out::println);
    }
}

判断一个指定的路径是否为目录

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private static void testIsDirectory() {
    File directory = new File(DIRECTORY_NAME);
    File file = new File(FILENAME);
    System.out.println(DIRECTORY_NAME + "是文件夹：" + directory.isDirectory());
    System.out.println(FILENAME + "是文件夹：" + file.isDirectory());
}

搜索指定目录的全部内容

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private static void testListAllFiles() {
    File rootDirectory = new File(ROOT_DIRECTORY);
    printFile(rootDirectory);
}

private static void printFile(File file) {
    if (file != null) {
        if (file.isDirectory()) {
            File[] subFiles = file.listFiles();
            if (subFiles != null) {
                Arrays.stream(subFiles).forEach(FileTest::printFile);
            }
        } else {
            System.out.println(file);
        }
    }
}

使用RandomAccessFile写入文件

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private static void testWriteFile() {
    File file = new File(FILENAME);
    try {
        RandomAccessFile raf = new RandomAccessFile(file, "rw");
        raf.writeBytes("lfdasj;fdalsj");
        raf.writeInt(42342);
        raf.writeBoolean(false);
        raf.writeChar('A');
        raf.writeFloat(45.5f);
        raf.writeDouble(76876.34);
        raf.close();
    } catch (IOException e) {
        e.printStackTrace();
    }
}