XMLHttpRequest не может загрузить http: // localhost: 3000/get

Question

Я звоню в службу js узла из моей другой программы, которая работает в tomcat, все в порядке, когда я использую приведенный ниже код.

var express = require('express') 
    , routes = require('./routes') 
    , user = require('./routes/user') 
    , http = require('http') 
    , path = require('path'), 

var app = express(); 

// all environments 
app.set('port', process.env.PORT || 3000); 
app.set('views', __dirname + '/views'); 
app.set('view engine', 'jade'); 
app.use(express.favicon()); 
app.use(express.logger('dev')); 
app.use(express.bodyParser()); 
app.use(express.methodOverride()); 
app.use(app.router); 
app.use(express.static(path.join(__dirname, 'public'))); 

// development only 
if ('development' == app.get('env')) { 
    app.use(express.errorHandler()); 
} 

app.get('/get', function (req, res) { 
    // Website you wish to allow to connect 
    res.setHeader('Access-Control-Allow-Origin', '*'); 

    // Request methods you wish to allow 
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE'); 

    // Request headers you wish to allow 
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type'); 

    // Set to true if you need the website to include cookies in the requests sent 
    // to the API (e.g. in case you use sessions) 
    res.setHeader('Access-Control-Allow-Credentials', true); 

     res.send('Hello World!'); 
    }); 


http.createServer(app).listen(app.get('port'), function(){ 
    console.log('Express server listening on port ' + app.get('port')); 
}); 

Но чтобы минимизировать код, я представил промежуточное программное обеспечение к нему, как показано ниже,

var express = require('express') 
    , routes = require('./routes') 
    , user = require('./routes/user') 
    , http = require('http') 
    , path = require('path'), 

var app = express(); 
var allowCrossDomain = function(req, res, next) { 
     // Website you wish to allow to connect 
    res.setHeader('Access-Control-Allow-Origin', '*'); 

    // Request methods you wish to allow 
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE'); 

    // Request headers you wish to allow 
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type'); 

    // Set to true if you need the website to include cookies in the requests sent 
    // to the API (e.g. in case you use sessions) 
    res.setHeader('Access-Control-Allow-Credentials', true); 
    next(); 
} 

// all environments 
app.set('port', process.env.PORT || 3000); 
app.set('views', __dirname + '/views'); 
app.set('view engine', 'jade'); 
app.use(express.favicon()); 
app.use(express.logger('dev')); 
app.use(express.bodyParser()); 
app.use(express.methodOverride()); 
app.use(app.router); 
app.use(allowCrossDomain); 
app.use(express.static(path.join(__dirname, 'public'))); 

// development only 
if ('development' == app.get('env')) { 
    app.use(express.errorHandler()); 
} 

app.get('/get', function (req, res) { 
     res.send('Hello World!'); 
    }); 


http.createServer(app).listen(app.get('port'), function(){ 
    console.log('Express server listening on port ' + app.get('port')); 
}); 

На данный момент я получаю XMLHttpRequest не может загрузить http://localhost:3000/get. В запрошенном ресурсе нет заголовка «Access-Control-Allow-Origin». Происхождение 'http://localhost:8083', следовательно, не допускается., я не знаю, где его не хватает.

Answer 1

Это мое обходное решение, надеюсь, что оно вам поможет.

var express = require('express'), 
    routes = require('./routes'), 
    user = require('./routes/user'), 
    http = require('http'), 
    path = require('path'), 

var app = express(); 
var allowCrossDomain = function(req, res, next) { 
     // Website you wish to allow to connect 
    res.setHeader('Access-Control-Allow-Origin', '*'); 

    // Request methods you wish to allow 
    res.setHeader('Access-Control-Allow-Methods', 'GET, POST, OPTIONS, PUT, PATCH, DELETE'); 

    // Request headers you wish to allow 
    res.setHeader('Access-Control-Allow-Headers', 'X-Requested-With,content-type'); 

    // Set to true if you need the website to include cookies in the requests sent 
    // to the API (e.g. in case you use sessions) 
    res.setHeader('Access-Control-Allow-Credentials', true); 
    next(); 
} 

// all environments 

app.set('views', __dirname + '/views'); 
app.set('view engine', 'jade'); 
app.use(express.favicon()); 
app.use(express.logger('dev')); 
app.use(express.bodyParser()); 
app.use(express.methodOverride()); 
app.use(app.router); 
app.use(allowCrossDomain); 
app.use(express.static(path.join(__dirname, 'public'))); 

// development only 
if ('development' == app.get('env')) { 
    app.use(express.errorHandler()); 
} 

app.get('/get', function (req, res) { 
     res.end('Hello World!'); 
    }); 


    app.listen(3000,function(){ 
    console.log("It's Started on PORT 3000"); 
}); 

Answer 2

var express = require('express') 
    , routes = require('./routes') 
    , user = require('./routes/user') 
    , http = require('http') 
    , path = require('path'), 

var app = express(); 


// all environments 

app.set('views', __dirname + '/views'); 
app.set('view engine', 'jade'); 
app.use(express.favicon()); 
app.use(express.logger('dev')); 
app.use(express.bodyParser()); 
app.use(express.methodOverride()); 
app.use(app.router); 

app.use(express.static(path.join(__dirname, 'public'))); 

// development only 


app.get('/get', function (req, res) { 
     res.end('Hello World!'); 
    }); 



    app.listen(3000,function(){ 
    console.log("It's Started on PORT 3000"); 
});