node中使用promise解决异步问题

fs = require(“fs”);
Q = require(“q”);

var test = function() {
var defer = Q.defer();
fs.readdir(“d:\test”, function(err, paths) {
if (err) defer.reject(err)
else defer.resolve(paths);
});
return defer.promise;
}

var printMessage = function(paths) {
var defer = Q.defer();
console.log(“printMessage中打印的paths：”);
console.log(paths);
defer.resolve(paths);
return defer.promise;
}

test().then(function(paths) {
return printMessage(paths)//需要返回*
}).then(function(paths) {
console.log(“printMessage函数执行之后打印的paths：”);
console.log(paths);
});