【js】Node.js的fs的使用方法

当然！Node.js 的 fs 模块提供了与文件系统进行交互的功能。以下是一些常见的操作示例代码：

1. 读取文件内容

异步读取文件

const fs = require('fs');

fs.readFile('example.txt', 'utf8', (err, data) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log(data);
});

同步读取文件

const fs = require('fs');

try {
    const data = fs.readFileSync('example.txt', 'utf8');
    console.log(data);
} catch (err) {
    console.error(err);
}

2. 写入文件内容

异步写入文件

const fs = require('fs');

const content = 'Some content to write into the file';

fs.writeFile('example.txt', content, 'utf8', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File has been written');
});

同步写入文件

const fs = require('fs');

const content = 'Some content to write into the file';

try {
    fs.writeFileSync('example.txt', content, 'utf8');
    console.log('File has been written');
} catch (err) {
    console.error(err);
}

3. 追加内容到文件

异步追加内容

const fs = require('fs');

const content = '\nAdditional content to append';

fs.appendFile('example.txt', content, 'utf8', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('Content has been appended');
});

同步追加内容

const fs = require('fs');

const content = '\nAdditional content to append';

try {
    fs.appendFileSync('example.txt', content, 'utf8');
    console.log('Content has been appended');
} catch (err) {
    console.error(err);
}

4. 删除文件

异步删除文件

const fs = require('fs');

fs.unlink('example.txt', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File has been deleted');
});

同步删除文件

const fs = require('fs');

try {
    fs.unlinkSync('example.txt');
    console.log('File has been deleted');
} catch (err) {
    console.error(err);
}

5. 创建目录

异步创建目录

const fs = require('fs');

fs.mkdir('exampleDir', { recursive: true }, (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('Directory has been created');
});

同步创建目录

const fs = require('fs');

try {
    fs.mkdirSync('exampleDir', { recursive: true });
    console.log('Directory has been created');
} catch (err) {
    console.error(err);
}

6. 读取目录内容

异步读取目录

const fs = require('fs');

fs.readdir('exampleDir', (err, files) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log(files);
});

同步读取目录

const fs = require('fs');

try {
    const files = fs.readdirSync('exampleDir');
    console.log(files);
} catch (err) {
    console.error(err);
}

7. 设置文件权限

异步设置文件权限

const fs = require('fs');

fs.chmod('example.txt', 0o755, (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File permissions have been changed');
});

同步设置文件权限

const fs = require('fs');

try {
    fs.chmodSync('example.txt', 0o755);
    console.log('File permissions have been changed');
} catch (err) {
    console.error(err);
}

8. 文件流操作

读取文件流

const fs = require('fs');

const readStream = fs.createReadStream('example.txt', 'utf8');

readStream.on('data', (chunk) => {
    console.log(chunk);
});

readStream.on('end', () => {
    console.log('No more data to read');
});

readStream.on('error', (err) => {
    console.error(err);
});

写入文件流

const fs = require('fs');

const writeStream = fs.createWriteStream('example.txt');

writeStream.write('This is the first line\n');
writeStream.write('This is the second line\n');
writeStream.end('This is the last line\n');

writeStream.on('finish', () => {
    console.log('All writes are now complete.');
});

writeStream.on('error', (err) => {
    console.error(err);
});

9. 监视文件变化

监视文件

const fs = require('fs');

fs.watch('example.txt', (eventType, filename) => {
    if (filename) {
        console.log(`${filename} file Changed: ${eventType}`);
    }
});

监视目录

const fs = require('fs');

fs.watch('exampleDir', (eventType, filename) => {
    if (filename) {
        console.log(`${filename} file Changed: ${eventType}`);
    }
});

10. 读取文件状态（获取文件信息）

异步读取文件状态

const fs = require('fs');

fs.stat('example.txt', (err, stats) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log(`File Size: ${stats.size}`);
    console.log(`File Permissions: ${stats.mode}`);
    console.log(`Is File: ${stats.isFile()}`);
    console.log(`Is Directory: ${stats.isDirectory()}`);
});

同步读取文件状态

const fs = require('fs');

try {
    const stats = fs.statSync('example.txt');
    console.log(`File Size: ${stats.size}`);
    console.log(`File Permissions: ${stats.mode}`);
    console.log(`Is File: ${stats.isFile()}`);
    console.log(`Is Directory: ${stats.isDirectory()}`);
} catch (err) {
    console.error(err);
}

11. 重命名文件或目录

异步重命名

const fs = require('fs');

fs.rename('oldName.txt', 'newName.txt', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File has been renamed');
});

同步重命名

const fs = require('fs');

try {
    fs.renameSync('oldName.txt', 'newName.txt');
    console.log('File has been renamed');
} catch (err) {
    console.error(err);
}

12. 删除目录

异步删除目录

const fs = require('fs');

fs.rmdir('exampleDir', { recursive: true }, (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('Directory has been deleted');
});

同步删除目录

const fs = require('fs');

try {
    fs.rmdirSync('exampleDir', { recursive: true });
    console.log('Directory has been deleted');
} catch (err) {
    console.error(err);
}

13. 复制文件

异步复制文件

const fs = require('fs');

fs.copyFile('source.txt', 'destination.txt', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File has been copied');
});

同步复制文件

const fs = require('fs');

try {
    fs.copyFileSync('source.txt', 'destination.txt');
    console.log('File has been copied');
} catch (err) {
    console.error(err);
}

14. 移动文件（通过重命名实现）

异步移动文件

const fs = require('fs');

fs.rename('source.txt', 'destination.txt', (err) => {
    if (err) {
        console.error(err);
        return;
    }
    console.log('File has been moved');
});

同步移动文件

const fs = require('fs');

try {
    fs.renameSync('source.txt', 'destination.txt');
    console.log('File has been moved');
} catch (err) {
    console.error(err);
}

15. 使用 fs.promises 进行异步操作

Node.js 提供了 fs.promises API，使得文件系统操作可以使用 async/await 语法。

读取文件内容

const fs = require('fs').promises;

async function readFile() {
    try {
        const data = await fs.readFile('example.txt', 'utf8');
        console.log(data);
    } catch (err) {
        console.error(err);
    }
}

readFile();

写入文件内容

const fs = require('fs').promises;

async function writeFile() {
    try {
        await fs.writeFile('example.txt', 'Some content to write into the file', 'utf8');
        console.log('File has been written');
    } catch (err) {
        console.error(err);
    }
}

writeFile();

追加内容到文件

const fs = require('fs').promises;

async function appendFile() {
    try {
        await fs.appendFile('example.txt', '\nAdditional content to append', 'utf8');
        console.log('Content has been appended');
    } catch (err) {
        console.error(err);
    }
}

appendFile();

删除文件

const fs = require('fs').promises;

async function deleteFile() {
    try {
        await fs.unlink('example.txt');
        console.log('File has been deleted');
    } catch (err) {
        console.error(err);
    }
}

deleteFile();

创建目录

const fs = require('fs').promises;

async function createDirectory() {
    try {
        await fs.mkdir('exampleDir', { recursive: true });
        console.log('Directory has been created');
    } catch (err) {
        console.error(err);
    }
}

createDirectory();

读取目录内容

const fs = require('fs').promises;

async function readDirectory() {
    try {
        const files = await fs.readdir('exampleDir');
        console.log(files);
    } catch (err) {
        console.error(err);
    }
}

readDirectory();

16. 处理文件系统的错误

在处理文件系统操作时，处理错误是非常重要的。以下是一些常见的错误处理示例：

异步操作中的错误处理

const fs = require('fs');

fs.readFile('nonexistent.txt', 'utf8', (err, data) => {
    if (err) {
        if (err.code === 'ENOENT') {
            console.error('File not found');
        } else {
            console.error(err);
        }
        return;
    }
    console.log(data);
});

同步操作中的错误处理

const fs = require('fs');

try {
    const data = fs.readFileSync('nonexistent.txt', 'utf8');
    console.log(data);
} catch (err) {
    if (err.code === 'ENOENT') {
        console.error('File not found');
    } else {
        console.error(err);
    }
}

使用 fs.promises 的错误处理

const fs = require('fs').promises;

async function readFile() {
    try {
        const data = await fs.readFile('nonexistent.txt', 'utf8');
        console.log(data);
    } catch (err) {
        if (err.code === 'ENOENT') {
            console.error('File not found');
        } else {
            console.error(err);
        }
    }
}

readFile();