nodejs----上传显示图片
Node.js实现图片的上传和显示，需要用到外部模块，formidable，这个模块是对解释上传的文件数据很好的抽象。文件上传，就是”处理“POST数据。
1,安装模块,打开nodejs安装目录,在命令行输入指令：
npm install formidable
2.引用formidable的模块，使用require指令。这个模块就是将通过http post请求提交的表单，在Node.js中可以被解释。
var formidable = require("formidable");
3.需要建立一个新的IncomingForm,对提交的表单的抽象表示，就可以用它解析request对象表单中需要的字。
var form = new formidable.IncomingForm();
4.实现图片的上传和显示这个引用因为要引用到formidable，必须把项目放在nodejs的安装目录下。
5.程序：
-----requestHandlers.js
-----server.js
-----router.js
-----index.js
requestHandlers.js
/*requestHandlers.js*/
var querystring = require("querystring"), fs = require("fs"), formidable = require ("formidable");
function start(response){
console.log("Request handler 'start' was called");
var body = '<html>' +
'<head>' +
'<meta http-equiv="Content-Type" content="text/html charset=UTF-8"/>' +
'</head>' +
'<body>' +
'<form action="/upload" enctype="multipart/form-data" method="post">' +
'<input type="file" name="upload" multiple="multiple"/>'+
'<input type="submit" value="Upload file"/>'+
'</form>' +
'</body>' +
'</html>';
response.writeHead(200,{"Content-Type":"text/html"});
response.write(body);
response.end();
}
function upload(response, request){
console.log("Request handler 'upload' was called");
/*formidable外部模块，解析上传的文件数据做了很好的抽象*/
var form = new formidable.IncomingForm();
//在应用目录下创建文件夹tmp，设置为上传路径
form.uploadDir = "tmp"
console.log("About to parse");
form.parse(request,function(error,fields, files){
console.log("parsing done");
console.log(files.upload.path);
//renameSync(oldpath,newpath)
//同步操作，需要try catch
try{
fs.renameSync(files.upload.path,"./tmp/test.png");
}catch(e){
console.log(e);
}
response.writeHead(200,{"Content-Type":"text/html"});
response.write("received image:<br/>");
//返回/show处理程序显示图片
response.write("<img src='/show'/>");
response.end();
});
}
//显示图片
function show(response){
console.log("Request handler 'show' was called.");
fs.readFile("./tmp/test.png","binary",function(error, file){
if(error){
response.writeHead(500,{"Content-Type":"text/plain"});
response.write(error + "/n");
response.end();
}else{
response.writeHead(200,{"Content-Type":"image/png"});
response.write(file,"binary");
response.end();
}
});
}
exports.start = start;
exports.upload = upload;
exports.show = show;
router.js
/*router.js*/
/*通过检查给定的路径对应的请求处理程序是否存在，如果存在的话直接调用相应的函数*/
function route(handle,pathname,response,request){
console.log("About to route a request for " + pathname);
if(typeof handle[pathname] === 'function'){
handle[pathname](response,request);
}else{
console.log("No request handler found for " + pathname);
response.writeHead(404,{"Content-Type":"text/html"});
response.write("404 Not found");
response.end();
}
}
exports.route = route;
server.js
/*server.js 处理请求模块*/
var http = require("http");
var url = require("url");
function start(route,handle){
function onRequest(request,response){
var pathname = url.parse(request.url).pathname;
console.log("Request for" + pathname + "Received.");
route(handle,pathname,response,request);
}
http.createServer(onRequest).listen(3000);
console.log("Server has started");
}
exports.start = start;
index.js
/*index.js 主模块*/
var server = require("./server");
var router = require("./router");
var requestHandlers = require("./requestHandlers");
var handle = {};
handle["/"] = requestHandlers.start;
handle["/start"] = requestHandlers.start;
handle["/upload"] = requestHandlers.upload;
handle["/show"] = requestHandlers.show;
server.start(router.route,handle);
6.启动应用：
node index.js
7.打开URL
http://127.0.0.1:3000
8.上传图片后：
9.图片被保存在路径：
