《node入门》学习

node入门原书地址：https://www.nodebeginner.org/index-zh-cn.html

node入门，循序渐进讲了javascript，node的回调和一些api的应用，很清晰，翻译也很给力。最终是一个例子，可以上传图片以及展示。

最后例子，遇到了麻烦，运行报错

可见零时文件已经创建

代码如下

 1 function upload(response, request){
 2     console.log("Request handler 'upload' was called.");
 3     
 4     var form = new formidable.IncomingForm();
 7     form.parse(request,function(error, fields, files){
 8         console.log("parsing done");
 9         console.log("F.U.P: "+files.upload.path);
10         fs.renameSync(files.upload.path, "tmp/test.png");
11         response.writeHead(200, {"Content-Type": "text/html"});
12         response.write("received image:<br/>");
13         response.write("<img src='/show' />");
14         response.end();
15     });
16     
17 };

搜过以后发现是fs.renameSync()不能跨盘操作，且不会新建文件夹，所以重新指定路径“form.uploadDir = "tmp"”，然后在目录新建tmp文件夹，最后在show函数读取的路径做修改

修改后代码

 1 function upload(response, request){
 2     console.log("Request handler 'upload' was called.");
 3     
 4     var form = new formidable.IncomingForm();
 5     form.uploadDir = "tmp";
 6     //console.log("about to parse");
 7     form.parse(request,function(error, fields, files){
 8         console.log("parsing done");
 9         console.log("F.U.P: "+files.upload.path);
10         /**
11         try{
12             fs.renameSync(files.upload.path, "tmp/test.png");
13         }catch(e){
14             console.log(e);
15         };
16         
17         fs.renameSync(files.upload.path, "tmp/test.png",function(error){
18             if(error){
19                 fs.unlink("/tmp/test.png");
20                 fs.rename(files.upload.path,"/tmp/test.png");
21             };
22         });
23         **/
24         fs.renameSync(files.upload.path, "tmp/test.png");
25         response.writeHead(200, {"Content-Type": "text/html"});
26         response.write("received image:<br/>");
27         response.write("<img src='/show' />");
28         response.end();
29     });
30     
31 };
32 
33 function show(response){
34     console.log("Request handle 'show' was called.");
35     fs.readFile("./tmp/test.png","binary",function(error,file){
36         if(error){
37             response.writeHead(500,{"Content-Type":"text/plain"});
38             response.write(error + "
");
39             response.end();
40         }else{
41             response.writeHead(200,{"Content-Type":"image/png"});
42             response.write(file,"binary");
43             response.end();
44         };
45     });
46 };

第五行及第35行有修改