node.js 读取文件

本文转载自：http://www.cnblogs.com/glczero/p/3932024.html

Node.js，在写一个文件上传的功能时候，调用fs.renameSync方法错误

function upload(response,request){
    console.log("requestHander upload was called")

    var form = new formidable.IncomingForm();

    console.log("about to parse");
    form.parse(request,function(error,fields,files){
        console.log("parsing done");
        fs.renameSync(files.upload.path,"./tmp/test.png");
        response.writeHead(200,{"Content-Type":"text/html"});
        response.write("reveived image : <br/>");
        response.write("<img src='/show' />");
        response.end();    
    })
    /*response.writeHead(200,{"Content-Type":"text/plain"});
    response.write("you have sent:"+querystring.parse(request).text);
    response.end();*/
}

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：

function upload(response,request){
    console.log("requestHander upload was called")

    var form = new formidable.IncomingForm();
    //form.uploadDir='tmp';

    console.log("about to parse");
    form.parse(request,function(error,fields,files){
        console.log("parsing done");
        //fs.renameSync(files.upload.path,"./tmp/test.png");
        var readStream=fs.createReadStream(files.upload.path);
        var writeStream=fs.createWriteStream("./tmp/test.png");
        readStream.pipe(writeStream);
        readStream.on('end',function(){
            fs.unlinkSync(files.upload.path);
        })

        response.writeHead(200,{"Content-Type":"text/html"});
        response.write("reveived image : <br/>");
        response.write("<img src='/show' />");
        response.end();    
    })
    /*response.writeHead(200,{"Content-Type":"text/plain"});
    response.write("you have sent:"+querystring.parse(request).text);
    response.end();*/
}

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）

function upload(response,request){
    console.log("requestHander upload was called")

    var form = new formidable.IncomingForm();
        form.uploadDir='tmp';

    console.log("about to parse");
    form.parse(request,function(error,fields,files){
        console.log("parsing done");
        fs.renameSync(files.upload.path,"./tmp/test.png");
        response.writeHead(200,{"Content-Type":"text/html"});
        response.write("reveived image : <br/>");
        response.write("<img src='/show' />");
        response.end();    
    })
    /*response.writeHead(200,{"Content-Type":"text/plain"});
    response.write("you have sent:"+querystring.parse(request).text);
    response.end();*/
}