[转]解决Node.js调用fs.renameSync报错 Er

原文地址 : http://blog.csdn.net/u013291076/article/details/53556985

在写一个文件上传的功能时候，调用fs.renameSync方法错误
出错 代码所在如下：

 1 function upload(response,request){
 2     console.log("upload called");
 3     var form = new formidable.IncomingForm();
 4     console.log("about to parse");
 5     form.parse(request, function(error, fields, files) {
 6         console.log("parsing done");
 7         fs.renameSync(files.upload.path, "./tmp/test.jpg");
 8         response.writeHead(200, {"Content-Type": "text/html"});
 9         response.write("received image:<br/>");
10         response.write("![](/show)");
11             response.end();
12     });
13 }

大致分析后，预计是因为 跨磁盘分区移动 或操作文件会有权限问题。
下面提供两种解决办法：
方法一：
主要利用fs的createReadStream、createWriteSream和unlinkSync方法
具体代码如下：

 1 function upload(response,request){
 2     console.log("upload called");
 3     var form = new formidable.IncomingForm();
 4     console.log("about to parse");
 5     form.parse(request, function(error, fields, files) {
 6         console.log("parsing done");

 7 //      fs.renameSync(files.upload.path, "./tmp/test.jpg");
 8         var readStream=fs.createReadStream(files.upload.path);
 9         var writeStream=fs.createWriteStream("./tmp/test.jpg");
10         readStream.pipe(writeStream);
11         readStream.on('end',function(){
12             fs.unlinkSync(files.upload.path);
13         });

14         response.writeHead(200, {"Content-Type": "text/html"});
15         response.write("received image:<br/>");
16         response.write("![](/show)");
17         response.end();
18     });
19 }

方法二：
这种就简洁很多了
添加一个 form.uploadDir='tmp' 即可（写一个临时路径）

 1 function upload(response,request){
 2     console.log("upload called");
 3     var form = new formidable.IncomingForm();
 4     form.uploadDir='tmp';
 5 
 6     console.log("about to parse");
 7     form.parse(request, function(error, fields, files) {
 8         console.log("parsing done");
 9         fs.renameSync(files.upload.path, "./tmp/test.jpg");
10         response.writeHead(200, {"Content-Type": "text/html"});
11         response.write("received image:<br/>");
12         response.write("![](/show)");
13         response.end();
14     });
15 }
16