Java 文件操作

//创建文件夹
public static void OnCreateFolder() {
    String path = "E:\temp\t01\t02\t03";
    File file = new File(path);
    try {
        if (!file.exists()) {
            // boolean result = file.mkdir();
            boolean result = file.mkdirs();
            System.out.println("create " + (result?"success":"fail"));
            //mkdir 只能创建一层目录, 父目录必须存在
            //mkdirs 必需但不存在的父目录也会一同创建出来
        }
    }
    catch (Exception e) {
        System.out.println("error mkdir");
        e.printStackTrace();
    }
}

//创建文件
public static void OnCreateFile() {
    String path = "E:\temp\file_01.doc";
    File file = new File(path);
    try {
        if (!file.exists()) {
            boolean result = file.createNewFile();
            System.out.println("create " + (result?"success":"fail"));
            //父目录必须存在
        }
    }
    catch (Exception e) {
        System.out.println("error createNewFile");
        e.printStackTrace();
    }
}

//删除文件/空文件夹
public static void OnDeleteFile() {
    // String path = "E:\temp\file_01.doc";
    String path = "E:\temp\t01\t02\";
    File file = new File(path);
    try {
        boolean result = file.delete();
        System.out.println("delete " + (result?"success":"fail"));
    }
    catch (Exception e) {
        System.out.println("error delete");
        e.printStackTrace();
    }
}

//文件属性
public static void OnProperty() {
    // String path = "E:\temp\t01\t02\t03";
    String path = "E:\temp\file_01.doc";
    File file = new File(path);

    if (file.exists()) {
        System.out.println(file.getName() + "的属性如下n文件长度为：" + file.length());
        System.out.println(file.isFile() ? "是文件" : "不是文件");
        System.out.println(file.isDirectory() ? "是目录" : "不是目录");
        System.out.println(file.canRead() ? "可读取" : "不");
        System.out.println(file.canWrite() ? "可写入" : "");
        System.out.println("最后修改日期为: " + new Date(file.lastModified()));
        System.out.println("绝对路径: " + file.getAbsolutePath());
    }
}

//字符流写入文件
public static void OnFileWriteBuffer() {
    String path = "E:\temp\file_01.txt";
    File file = new File(path);
    String content = "新内容: " + new Date() + " File Writern";
    FileWriter fileWriter = null;
    BufferedWriter bufferedWriter = null;

    try {
        if (!file.exists()) {
            boolean result = file.createNewFile();
            System.out.println("create " + (result?"success":"fail"));
            //父目录必须存在
        }
        boolean append = true; //追加 or 覆盖
        fileWriter = new FileWriter(file.getAbsoluteFile(), append);
        bufferedWriter = new BufferedWriter(fileWriter);
        bufferedWriter.write(content);
        bufferedWriter.close();
        fileWriter.close();
    }
    catch (Exception e) {
        System.out.println("error file write");
        e.printStackTrace();
    }
}

//字节流写入文件
public static void OnFileWriteStream() {
    String path = "E:\temp\file_01.txt";
    File file = new File(path);
    String content = "新内容: " + new Date() + " File Streamn";
    FileOutputStream fileOutputStream = null;

    try {
        if (!file.exists()) {
            boolean result = file.createNewFile();
            System.out.println("create " + (result?"success":"fail"));
            //父目录必须存在
        }
        boolean append = true; //追加 or 覆盖
        fileOutputStream = new FileOutputStream(file, append);
        fileOutputStream.write(content.getBytes(StandardCharsets.UTF_8));
        fileOutputStream.close();
    }
    catch (Exception e) {
        System.out.println("error file write");
        e.printStackTrace();
    }
}

//Access写入文件
public static void OnFileWriteAccess() {
    String path = "E:\temp\file_01.txt";
    File file = new File(path);
    String content = "新内容: " + new Date() + " Accessn";
    RandomAccessFile randomAccessFile = null;

    try {
        if (!file.exists()) {
            boolean result = file.createNewFile();
            System.out.println("create " + (result?"success":"fail"));
            //父目录必须存在
        }
        randomAccessFile = new RandomAccessFile(path, "rw"); //r:只读 rw:读写
        //清空原来的数据
        randomAccessFile.setLength(0);
        //将写文件指针移到文件尾
        randomAccessFile.seek(randomAccessFile.length());
        randomAccessFile.write(content.getBytes(StandardCharsets.UTF_8));
        randomAccessFile.close();
    }
    catch (Exception e) {
        System.out.println("error file write");
        e.printStackTrace();
    }
}

//字符流读取文件
public static String OnFileReadBuffer() {
    String s = "";
    String path = "E:\temp\file_01.txt";
    File file = new File(path);
    if (!file.exists())
        return "";

    BufferedReader bufferedReader = null;
    try {
        bufferedReader = new BufferedReader(new FileReader(file));
        String temp;
        while((temp=bufferedReader.readLine()) != null) {
            s += temp + "n";
        }
    } catch(Exception e) {
        e.printStackTrace();
    } finally {
        try {
            if (bufferedReader != null)
                bufferedReader.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    System.out.println("file content:n" + s);
    return s;
}

//工具: 清空文件夹
public static boolean onDeleteDirectory(String path) {
    File file = new File(path);
    if(!file.exists()) { //判断是否待删除目录是否存在
        System.err.println("the directory are not exists");
        return false;
    }

    String[] content = file.list(); //取得当前目录下所有文件和文件夹
    for(String name : content) {
        File temp = new File(path, name);
        if(temp.isDirectory()) { //判断是否是目录
            onDeleteDirectory(temp.getAbsolutePath()); //递归调用，删除目录里的内容
            temp.delete(); //删除空目录
        } else {
            if(!temp.delete()) {//直接删除文件
                System.err.println("failed to delete " + name);
            }
        }
    }
    return true;
}