我只是在NodeJS上尝试一些代码,我是NodeJS的新手。我写了下面的代码块。
var fs = require('fs'),
os = require('os');
var filename = 'Server.ini';
var serverData = os.hostname() + "\n" + os.platform() + "\n" + os.type() + "\n";
fs.existsSync(filename, function(exists) {
if(exists) {
console.log("1. " + filename + " file found. Server needs to be updated.")
fs.unlinkSync(filename, function(error) {
if(error) throw error;
console.log("2. " + filename + " is been unlinked from server.");
});
} else {
console.log("1. " + filename + " not found.");
console.log("2. Server needs to be configured.");
}
});
fs.openSync(filename, "w+", function(error) {
if(error) throw error;
console.log("3. " + filename + " file is been locked.");
});
fs.writeFileSync(filename, serverData, function(error) {
if(error) throw error;
console.log("4. " + filename + " is now updated.");
fs.readFileSync(filename, 'utf-8', function(error, data) {
if(error) throw error;
console.log("5. Reading " + filename + " file");
console.log("6. " + filename + " contents are below\n");
console.log(data);
console.log("-------THE END OF FILE-------");
});
});
我已经编辑了代码并添加了同步,但现在它给了我以下错误:
D:\NodeJS\fs>node eg5.js
buffer.js:382
throw new Error('Unknown encoding');
^
Error: Unknown encoding
at Buffer.write (buffer.js:382:13)
at new Buffer (buffer.js:261:26)
at Object.fs.writeFileSync (fs.js:758:12)
at Object.<anonymous> (D:\NodeJS\fs\eg5.js:28:4)
at Module._compile (module.js:449:26)
at Object.Module._extensions..js (module.js:467:10)
at Module.load (module.js:356:32)
at Function.Module._load (module.js:312:12)
at Module.runMain (module.js:492:10)
at process.startup.processNextTick.process._tickCallback (node.js:244:9)
D:\NodeJS\fs>
我的代码中有关于utf8的错误!
答案 0 :(得分:7)
readFileSync
不接受回调。我想您想要使用readFile
。
writeFileSync
您遇到同样的问题。当同步使用IO功能时,那些调用完成的回调没有任何意义。最好使用异步函数(没有“Sync”),注意它们采用不同的参数。
文档总是提及"utf8"
,而不是"utf-8"
,我不知道后者是否受支持。
答案 1 :(得分:4)
根据node.js API文档,writeFileSync有3个参数:
它没有指定回调。只有异步版本才会进行回调。
http://www.nodejs.org/api/fs.html#fs_fs_writefilesync_filename_data_options
尝试使用此代替writeFileSync块:
fs.writeFileSync(filename, serverData, { encoding: 'utf8'});
console.log("4. " + filename + " is now updated.");
var contents = fs.readFileSync(filename, 'utf8');
console.log("5. Reading " + filename + " file");
console.log("6. " + filename + " contents are below\n");
console.log(contents);
console.log("-------THE END OF FILE-------");