nodejs 爬虫

var moment = require(‘moment‘);

exports.inc = function(n, callback, timeout) {
    timeout = timeout || 200;
    setTimeout(function() {
        callback(null, n+1);
    }, timeout);
};

exports.fire = function(obj, callback, timeout) {
    timeout = timeout || 200;
    setTimeout(function() {
        callback(null, obj);
    }, timeout);
};

exports.err = function(errMsg, callback, timeout) {
    timeout = timeout || 200;
    setTimeout(function() {
        callback(errMsg);
    }, timeout);
};

// utils
exports.log = function(msg, obj) {
    process.stdout.write(moment().format(‘ss.SSS‘)+‘> ‘);
    if(obj!==undefined) {
        process.stdout.write(msg);
        console.log(obj);
    } else {
        console.log(msg);
    }
};

exports.wait = function(mils) {
    var now = new Date;
    while(new Date - now <= mils);
}

//获得页面数据
var http = require("http");
//分析页面数据，提前内容
var cheerio = require("cheerio");
//过滤没用的数据 如空格等
var sanitize = require("validator");
//操作文件，保存结果
var fs = require(‘fs‘);


var scrapy = {};
scrapy.get = function(url, callback) {
  http.get(url, function(res) {

    var size = 0;
    var chunks = [];

    res.on(‘data‘, function(chunk) {
      size += chunk.length;
      chunks.push(chunk);
    });

    res.on(‘end‘, function() {
      var data = Buffer.concat(chunks, size);
      callback(null, data);
    });

  }).on(‘error‘, function(e) {
    callback(e, null);
  });
}

var getPage = function(pageUrl, callback){
  scrapy.get(pageUrl, function(err, data){
    if(err){
      callback(err);
    }

    var html = data.toString();
    $ = cheerio.load(html);
      //title link, link to detail page
      var news = $(‘.cell .topic_title_wrapper a‘);   
      callback(null, news);
    });
}

var getDetail = function(detailUrl, callback){  
  scrapy.get(detailUrl, function(err, data){
    if(err){
      callback(err);
    }

    var html = data.toString();
    $ = cheerio.load(html);  
    var item = {};
    item.href = detailUrl;
    $(‘.header .topic_full_title .put_top‘).remove(); //删除 “置顶”
    item.title = sanitize.escape(sanitize.trim($(‘.header .topic_full_title‘).text()));
    item.content = sanitize.escape(sanitize.trim($(‘.inner.topic .topic_content‘).text()));

    callback(null, item);
  });
}

var save = function(fileName, data) {
  var result = JSON.stringify(data);
  fs.writeFileSync(fileName, result);
}

exports.getUrl = scrapy.get;
exports.getPage = getPage;
exports.getDetail = getDetail;
exports.save = save;

//自定义console.log 加入了输出时间
var utils = require("./utils");
var log = utils.log;
//异步操作 如each， filter
var async = require("async");
//计算花费时间
var ts = require("timespans")
//过滤没用的数据 如空格等
var sanitize = require("validator");
var url = require("./module_url")


var baseUrl = ‘http://cnodejs.org‘;
var pageUrl = baseUrl + ‘/?page=‘;
var isOnlyTitle = true;
var pages = [];
for (var i = 1; i < 4; i++) {
    pages.push(i);
};

ts.start();
var titles = {};
//page 之间并行
async.forEach(pages, function(page, callback_each){
    titles[page] = [];

    url.getPage(pageUrl + page, function(err, news){
        if(err){
            log("page error");
            return;
        }

        if (news.length === 0) {
              log("no data for the page:" + page);
              return;
        }
        
        async.filter(news, function(index, callback){
            var detailUrl = baseUrl + news[index].attribs[‘href‘];

            if(isOnlyTitle){
                var curNew = news[index];
                var item = {};
                item.href = detailUrl;        
                $(curNew).find(".put_top").remove();    //删除 “置顶”                
                item.title = sanitize.escape(sanitize.trim($(curNew).text()));

                titles[page][index] = item;

                callback(true);
            }
            else{
                url.getDetail(detailUrl, function(err, item){
                    if(err){
                        log("detail error");
                        return;
                    }
                    titles[page][index] = item;
                    //titles[page].push(item);

                    callback(true);
                });
            }
        }, function(result){
            //log("filter news:", result);
            callback_each(null);
        });
        
    });
}, function(err){
    ts.stop();
    //ts.pause();    ---   ts.continue();
    console.log(‘total: %s pause: %s used: %s‘, ts.elapsedtime(), ts.pausetime(), ts.usedtime());
    log(titles);
    //url.save("cnodejs.json", titles);
});