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nextµÄʱºò£¬È»ºó¾Í»áÄæÐòÖ´ÐÐÇ°ÃæÄÇЩÖмä¼þʣϵÄÂß¼¡£Ö±½ÓÉϸö¹ÙÍøµÄÀý×Ó£º
var koa = require('koa');
var app = koa();
// response-timeÖмä¼þ
app.use(function *(next){
var start = new Date;
yield next;
var ms = new Date - start;
this.set('X-Response-Time', ms + 'ms');
});
// loggerÖмä¼þ
app.use(function *(next){
var start = new Date;
yield next;
var ms = new Date - start;
console.log('%s %s - %s', this.method, this.url,
ms);
});
// ÏìÓ¦Öмä¼þ
app.use(function *(){
this.body = 'Hello World';
});
app.listen(3000); |
ÉÏÃæµÄÖ´ÐÐ˳Ðò¾ÍÊÇ£ºÇëÇó ==> response-timeÖмä¼þ ==> loggerÖмä¼þ
==> ÏìÓ¦Öмä¼þ ==> loggerÖмä¼þ ==> response-timeÖмä¼þ
==> ÏìÓ¦¡£
¸üÏêϸÃèÊö¾ÍÊÇ£ºÇëÇó½øÀ´£¬ÏȽøµ½response-timeÖмä¼þ£¬Ö´ÐÐ var start =
new Date; È»ºóÓöµ½yield next£¬ÔòÔÝÍ£response-timeÖмä¼þµÄÖ´ÐУ¬Ìø×ª½øloggerÖмä¼þ£¬Í¬Àí£¬×îºó½øÈëÏìÓ¦Öмä¼þ£¬ÏìÓ¦Öмä¼þÖÐûÓÐyield
next´úÂ룬Ôò¿ªÊ¼ÄæÐòÖ´ÐУ¬Ò²¾ÍÊÇÔÙÏÈÊǻص½loggerÖмä¼þ£¬Ö´ÐÐyield nextÖ®ºóµÄ´úÂ룬ִÐÐÍêºóÔٻص½response-timeÖмä¼þÖ´ÐÐyield
nextÖ®ºóµÄ´úÂë¡£
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¶øKoaµÄÖмä¼þÊÇÔËÐÐÔÚ co º¯ÊýÏµģ¬¶øtj´óÉñµÄcoº¯ÊýÄܹ»°ÑÒì²½±äͬ²½£¬Ò²¾Í˵£¬±àдKoaµÄÖмä¼þµÄʱºò¿ÉÒÔÕâÑùд£¬¾ÍÄÃÉÏÃæÄǸödemo×îºóµÄÏìÓ¦Öмä¼þÀ´Ëµ¿ÉÒԸijÉÕâÑù£º
app.use(function*(){
var text = yield new Promise(function(resolve){
fs.readFile('./index.html', 'utf-8', function(err,
data){
resolve(data);
})
});
this.body = text;
}); |
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var MongoClient
= require("mongodb").MongoClient;
app.use(function *(){
var db = yield MongoClient.connect('mongodb://127.0.0.1:27017/myblog');
var collection = db.collection('document');
var result = yield collection.find({}).toArray();
db.close()
}); |
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×Ô¼ºÊµÏÖÁËÒ»¸ö¼òµ¥µÄcoº¯Êý£¬´«ÈëÒ»¸ögenerator£¬»ñÈ¡generatorµÄº¯Êý¶ÔÏó£¬È»ºó¶¨ÒåÒ»¸önext·½·¨ÓÃÓڵݹ飬ÔÚnext·½·¨ÀïÖ´ÐÐgenerator.next()²¢ÇÒ´«Èëdata£¬Ö´ÐÐÍêgenerator.next()»á»ñÈ¡µ½{value:XX,
done: true|false}µÄ¶ÔÏó£¬Èç¹ûdoneΪtrue£¬ËµÃ÷generatorÒѾµü´úÍê±Ï£¬Í˳ö¡£
·ñÔò£¬¼ÙÉ赱ǰִÐе½yield new Promise()£¬Ò²¾ÍÊÇ·µ»ØµÄresult.value¾ÍÊÇPromise¶ÔÏóµÄ£¬Ö±½ÓÖ´ÐÐPromiseµÄthen·½·¨£¬²¢ÇÒÔÚthen·½·¨µÄonFulfilled»Øµ÷£¨Ò²¾ÍÊÇPromiseÖеÄÒì²½Ö´ÐÐÍê±Ïºó£¬µ÷ÓÃresolveµÄʱºò»á´¥·¢¸Ã»Øµ÷º¯Êý£©ÖÐÖ´ÐÐnext·½·¨½øÐеݹ飬²¢ÇÒ½«onFulfilledÖд«ÈëµÄÊý¾Ý´«Èënext·½·¨£¬Ò²¾Í¿ÉÒÔÔÚÏÂÒ»´Îgenerator.next()ÖаÑÊý¾Ý´«½øÈ¥¡£
// co¼òÒ×ʵÏÖ
function co(generator){
var gen = generator();
var next = function(data){
var result = gen.next(data);
if(result.done) return;
if (result.value instanceof Promise) {
result.value.then(function (d) {
next(d);
}, function (err) {
next(err);
})
}else {
next();
}
};
next();
} |
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// test
co(function*(){
var text1 = yield new Promise(function(resolve){
setTimeout(function(){
resolve("I am text1");
}, 1000);
});
console.log(text1);
var text2 = yield new Promise(function(resolve){
setTimeout(function(){
resolve("I am text2");
}, 1000);
});
console.log(text2);
}); |
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nextÀïµÄnext£©¡¢»¹ÓÐÒ»¸öÊÇÓÃÓÚ±£´ægeneratorº¯Êý¶ÔÏóµÄÊý×égs£¬¡£È»ºó»ñÈ¡µ±Ç°Öмä¼þgenerator£¬²¢ÇÒ»ñÈ¡µ½¸ÃgeneratorµÄº¯Êý¶ÔÏ󣬽«º¯Êý¶ÔÏó·ÅÈëgsÊý×éÖб£´æ£¬ÔÙÖ´ÐÐgenerator.next()¡£
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next£¬ËµÃ÷ÒªÌø×ªµ½ÏÂÒ»¸öÖмä¼þ£¬´Ëʱ¶Ôindex++£¬È»ºó´ÓgensÊý×éÀï»ñÈ¡ÏÂÒ»¸öÖмä¼þÖØ¸´ÉÏÒ»¸öÖмä¼þµÄ²Ù×÷¡£
µ±Ö´Ðе½µÄÖмä¼þÀïûÓÐyield nextʱ£¬²¢ÇÒµ±¸ÃgeneratorÒѾִÐÐÍê±Ï£¬Ò²¾ÍÊÇ·µ»ØµÄdoneΪtrueµÄʱºò£¬ÔÙÄæÐòÖ´ÐУ¬´Ó´ËǰÓÃÓÚ±£´ægeneratorµÄº¯Êý¶ÔÏógsÊý×é»ñÈ¡µ½ÉÏÒ»¸ögeneratorº¯Êý¶ÔÏó£¬È»ºóÖ´ÐиÃgeneratorµÄnext·½·¨¡£Ö±µ½È«²¿Ö´ÐÐÍê±Ï¡£
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//¼òÒ×ʵÏÖkoaµÄÖмä¼þЧ¹û
var gens = [];
function use(generetor){
gens.push(generetor);
}
function trigger(){
var index = 0;
var ne = {};
var gs = [],
g;
next();
function next(){
//»ñÈ¡µ±Ç°Öмä¼þ£¬´«Èënext±ê¼Ç£¬¼´µ±yield nextʱ´¦ÀíÏÂÒ»¸öÖмä¼þ
var gen = gens[index](ne);
//±£´æÊµÀý»¯µÄÖмä¼þ
gs.push(gen);
co(gen)
}
function co(gen, data){
if(!gen) return;
var result = gen.next(data);
// µ±µ±Ç°µÄgeneratorÖмä¼þÖ´ÐÐÍê±Ï£¬½«Ö´ÐÐË÷Òý¼õÒ»£¬»ñÈ¡ÉÏÒ»¼¶µÄÖмä¼þ²¢ÇÒÖ´ÐÐ
if(result.done){
index--;
if(g = gs[index]){
co(g);
}
return;
}
// Èç¹ûÖ´Ðе½Promise£¬Ôòµ±PromiseÖ´ÐÐÍê±ÏÔÙ½øÐеݹé
if(result.value instanceof Promise){
result.value.then(function(data){
co(gen, data);
})
}else if(result.value === ne){
// µ±Óöµ½yield nextʱ£¬Ö´ÐÐÏÂÒ»¸öÖмä¼þ
index++;
next();
}else {
co(gen);
}
}
} |
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// test
use(function*(next){
var d = yield new Promise(function(resolve){
setTimeout(function(){
resolve("step1")
}, 1000)
});
console.log(d);
yield next;
console.log("step2");
});
use(function*(next){
console.log("step3");
yield next;
var d = yield new Promise(function(resolve){
setTimeout(function(){
resolve("step4")
}, 1000)
});
console.log(d);
});
use(function*(){
var d = yield new Promise(function(resolve){
setTimeout(function(){
resolve("step5")
}, 1000)
});
console.log(d);
console.log("step6");
});
trigger(); |
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var gens = [];
function use(generetor){
gens.push(generetor);
}
// ʵÏÖcoº¯Êý
function co(flow, isGenerator){
var gen;
if (isGenerator) {
gen = flow;
} else {
gen = flow();
}
return new Promise(function(resolve){
var next = function(data){
var result = gen.next(data);
var value = result.value;
// Èç¹ûµ÷ÓÃÍê±Ï£¬µ÷ÓÃresolve
if(result.done){
resolve(value);
return;
}
// Èç¹ûΪyieldºóÃæ½ÓµÄΪgenerator£¬´«Èëco½øÐеݹ飬²¢ÇÒ½«promise·µ»Ø
if (typeof value.next === "function"
&& typeof value.throw === "function")
{
value = co(value, true);
}
if(value.then){
// µ±promiseÖ´ÐÐÍê±Ï£¬µ÷ÓÃnext´¦ÀíÏÂÒ»¸öyield
value.then(function(data){
next(data);
})
}
};
next();
});
}
function trigger(){
var prev = null;
var m = gens.length;
co(function*(){
while(m--){
// ÐγÉÁ´Ê½generator
prev = gens[m].call(null, prev);
}
// Ö´ÐÐ×îÍâ²ãgenerator·½·¨
yield prev;
})
} |
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ÉÏÃæÐ´µÄÈý¸ö´úÂë·ÅÔÚÁËgithub£º
https://github.com/whxaxes/node-test/blob/master/other/myco.js
https://github.com/whxaxes/node-test/blob/master/other/mykoa.js
https://github.com/whxaxes/node-test/blob/master/other/mykoa_2.js
|