本文实例讲述了Node.js图片上传和显示方法。分享给大家供大家参考，具体如下：
index.js
rush:js;">
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);
server.js
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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;
requestHandlers.js
rush:js;">
var querystring = require("querystring"),fs = require("fs"),formidable = require("formidable");
function start(response) {
console.log("Request handler 'start' was called.");
var body = ''+
''+
''+
''+
''+
''+
''+
''+
'';
response.writeHead(200,{"Content-Type": "text/html"});
response.write(body);
response.end();
}
function upload(response,request) {
console.log("Request handler 'upload' was called.");
var form = new formidable.IncomingForm();
form.uploadDir = "D:\\min\\nodejsExample2\\tmp";
console.log("about to parse1");
form.parse(request,function(error,fields,files) {
console.log("parsing done");
console.log(files.upload.path);
fs.renameSync(files.upload.path,"D:\\min\\nodejsExample2\\tmp\\test.png");
response.writeHead(200,{"Content-Type": "text/html"});
response.write("received image:
"); response.write("
");
response.end();
});
}
function show(response) {
console.log("Request handler 'show' was called.");
fs.readFile("D:\\min\\nodejsExample2\\tmp\\test.png","binary",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;
"); response.write("
router.js
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function route(handle,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;
result:
知识点：
其中用到了fs模块的readFile读取文件，它有同步和异步两个版本。node.js中，并不是所有的API都提供了异步和同步版本，node.js不鼓励使用同步I/O。
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//this is async 异步
/*
fs.readFile调用时所做的工作只是将异步式I/O请求发送给了操作系统，然后立即返回并执行后面的语句，执行完以后进入事件循环监听事件。
当fs接收到I/O请求完成的事件时，事件循环会主动调用回调函数以完成后续工作。
*/
var fs = require('fs');
fs.readFile('file.txt','utf-8',function(err,data){
if (err){
console.error(err);
} else {
console.log(data);
}
});
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//this is sync 同步
var fs = require('fs');
var data = fs.readFileSync('file.txt','utf-8');
console.log(data);
console.log('end.');
希望本文所述对大家nodejs程序设计有所帮助。
原文地址：https://www.jb51.cc/nodejs/39994.html
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