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【js】Node.js的fs的使用方法

news 来源：原创 2024/9/30 4:45:37

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();