[node.js] fs.renameSync()报错

  初学node.js，跟着node入门，操作了一遍。在最后一步，上传图片并显示时遇到报错

 fs.js:115
    throw err;
    ^
    Error: ENOENT: no such file or directory, rename 'C:\Users\catcher\AppData\Local\Temp\upload_16f7bede547980c767e1e031a3720f67' -> '/tmp/test.png'
    at Object.renameSync (fs.js:594:3)
    at C:\IdeaProjects\nodejs\requestHandlers.js:34:8
    at IncomingForm.<anonymous> (C:\IdeaProjects\nodejs\node_modules\formidable\lib\incoming_form.js:107:9)
    at IncomingForm.emit (events.js:182:13)
    at IncomingForm._maybeEnd (C:\IdeaProjects\nodejs\node_modules\formidable\lib\incoming_form.js:557:8)
    at C:\IdeaProjects\nodejs\node_modules\formidable\lib\incoming_form.js:238:12
    at WriteStream.<anonymous> (C:\IdeaProjects\nodejs\node_modules\formidable\lib\file.js:79:5)
    at Object.onceWrapper (events.js:273:13)
    at WriteStream.emit (events.js:182:13)
    at finishMaybe (_stream_writable.js:641:14)

    
根据报错信息，查找到相应的代码，

fs.renameSync(files.upload.path, "/tmp/test.png");

首先想到的是代码中是相对路径，导致不能查找到文件所在的位置，于是将路径补全

fs.renameSync(files.upload.path,"C:/IdeaProjects/nodejs/tmp/test.png");

还是同样的报错

Error: ENOENT: no such file or directory, rename 'C:\Users\catcher\AppData\Local\Temp\upload_cb107f6decde929aff2b86f5bfb3a330' -> 'C:/IdeaProjects/nodejs/tmp/test.png'

    
仔细观察后发现在路径名中可能存在的左右反斜杠的问题。即在windows中路径名间隔符为右反斜杠'\'，而在Linux和mac os中都是左反斜杠'/'。于是修改代码为

fs.renameSync(files.upload.path,"C:\IdeaProjects\nodejs\tmp\test.png");

依然报错

Error: ENOENT: no such file or directory, rename 'C:\Users\catcher\AppData\Local\Temp\upload_5b3fdf35fbb17a8579b5c2245f070543' -> 'C:IdeaProjects  odejs   mp      est.png'

    
问题在于右反斜杠是转义字符，所以路径名称应该为

fs.renameSync(files.upload.path,"C:\\IdeaProjects\\nodejs\\tmp\\test.png");

遗憾的是依然报错，

Error: ENOENT: no such file or directory, rename 'C:\Users\catcher\AppData\Local\Temp\upload_d3cceb8f8c01ae2a796d1f356e91ae0f' -> 'C:\IdeaProjects\nodejs\tmp\test.png'

不过显示的路径算是对了。
再次阅读报错信息后 no such file or directory ，会不会是文件夹tmp需要手动创建？（没错，我以为该方法会自动创建不存在的文件夹，所以在一开始我还尝试通过everything去查找tmp文件夹）自己创建文件夹tmp之后，成功上传图片并预览。
而之前反复改动的文件路径，以下三种方式亲测可用：

fs.renameSync(files.upload.path, "./tmp/test.png"); //注意点号

fs.renameSync(files.upload.path, "C:\\IdeaProjects\\nodejs\\tmp\\test.png");

fs.renameSync(files.upload.path, "C:/IdeaProjects/nodejs/tmp/test.png");

 

附：在网上查询资料，提到fs.renameSync() 不允许跨分区移动文件。解决办法如下：

https://stackoverflow.com/questions/4568689/how-do-i-move-file-a-to-a-different-partition-or-device-in-node-js
   

 var fs = require('fs');
 //var util = require('util');
 var is = fs.createReadStream('source_file');
 var os = fs.createWriteStream('destination_file');
 is.pipe(os);
 is.on('end',function() {
    fs.unlinkSync('source_file');
 });
 /* node.js 0.6 and earlier you can use util.pump:
 util.pump(is, os, function() {
     fs.unlinkSync('source_file');
 });
 */