fs.close()方法用于异步关闭给定的文件描述符,从而清除与之关联的文件。这将允许文件描述符重用于其他文件。在文件描述符上执行其他操作时,在文件描述符上调用fs.close()可能会导致未定义的行为。
用法:
fs.close( fd, callback )
参数:此方法接受上述和以下所述的两个参数:
- fd:它是一个整数,表示要关闭的文件的文件描述符。
- callback:该方法执行时将调用该函数。
- err:如果方法失败,将抛出此错误。
以下示例说明了Node.js中的fs.close()方法:
范例1:本示例显示文件描述符的关闭。
// Node.js program to demonstrate the
// fs.close() method
// Import the filesystem module
const fs = require('fs');
// Get the file descriptor of the given path
file_descriptor = fs.openSync("example.txt");
console.log("The file descriptor is:", file_descriptor);
// Close the file descriptor
fs.close(file_descriptor, (err) => {
if (err)
console.error('Failed to close file', err);
else {
console.log("\n> File Closed successfully");
}
});
输出:
The file descriptor is:3 > File Closed successfully
范例2:此示例显示了文件描述符的关闭,并尝试再次访问该关闭的文件描述符。
// Node.js program to demonstrate the
// fs.close() method
// Import the filesystem module
const fs = require('fs');
// Get the file descriptor of the given path
file_descriptor = fs.openSync("example.txt");
console.log("The file descriptor is:", file_descriptor);
console.log("\n> Finding the stats of the file");
try {
// Attempting to find stats of file before closing
statsObj = fs.fstatSync(file_descriptor);
console.log("Stats of the file generated");
// Closing the file descriptor
console.log("\n> Closing the file descriptor");
fs.close(file_descriptor, (err) => {
if (err)
console.error("Failed to close file", err);
else {
console.log("File Closed successfully");
try {
// Attempting to find stats of file after closing
console.log("\n> Finding the stats of the file again");
statsObj = fs.fstatSync(file_descriptor);
console.log("Stats of the file generated");
}
catch (err) {
console.error("Cannot find stats of file", err);
}
}
});
} catch (err) {
console.error("Cannot find stats of file", err);
}
输出:
The file descriptor is:3 > Finding the stats of the file Stats of the file generated > Closing the file descriptor File Closed successfully > Finding the stats of the file again Cannot find stats of file Error:EBADF:bad file descriptor, fstat at Object.fstatSync (fs.js:897:3) at G:\tutorials\nodejs-fs-close\index.js:42:23 at FSReqCallback.oncomplete (fs.js:146:23) { fd:3, errno:-4083, syscall:'fstat', code:'EBADF' }
参考: https://nodejs.org/api/fs.html#fs_fs_close_fd_callback
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注:本文由纯净天空筛选整理自sayantanm19大神的英文原创作品 Node.js | fs.close() Method。非经特殊声明,原始代码版权归原作者所有,本译文未经允许或授权,请勿转载或复制。