简单的node爬虫练手，循环中的异步转同步
转载：https://blog.csdn.net/qq_24504525/article/details/77856989
看到网上一些基于node做的爬虫项目，自己也想写一下练手，正好同事需要各省市的信息
一、开发环境搭建
- node 安装最新版 后面会用到async、await
- webstrom编辑器
- 新建reptitle文件夹 --> npm init (初始化工程)
二、爬取页面分析
- 入口 ，获取该页面所有的省市，记录下省市名称，及html地址
- 查询省市下面的市区
- 依次爬取，略。。
三、关键代码
1. 代码分析- cheerio包用于解析页面中的html,用法同jquery
- fs 生成文件
- http 发起get请求页面
- async 用于解决异步
- iconv、bufferhelper 用于解析中文乱码
2. 因为http发起的请求是异步，循环中的异步函数不能按照想要的既定顺序执行，所以我用es6、7中的promise async await 将异步函数转化成同步
3. 代码
let http = require("http");
let cheerio = require("cheerio");
let fs = require("fs");
let async = require("async");
let iconv = require('iconv-lite');
let BufferHelper = require('bufferhelper');
let initUrl = "http://www.stats.gov.cn/tjsj/tjbz/tjyqhdmhcxhfdm/2016/index.html";
let url = "http://www.stats.gov.cn/tjsj/tjbz/tjyqhdmhcxhfdm/2016/";//初始url
let dataSource = [];
/**
* @method 生成文件
* @param fileName
* @param text
*/
const createTxt =(fileName,text) =>{
return new Promise((resolve,reject)=>{
fs.appendFile("spider/data/"+fileName+".txt",text,"utf-8",function(err){
if(err){
console.log(err)
}else{
resolve(true)
}
})
})
};
/**
* @method promise封装http请求
* @returns {Promise.<void>}
*/
const httpGet = (url) =>{
return new Promise((resolve,reject)=>{
http.get(url,(res)=>{
let buffer = new BufferHelper();
res.on("data",(data)=>{
buffer.concat(data);
});
res.on("end",()=>{
let buf = buffer.toBuffer();
let html = iconv.decode(buf,'GBK');
let $ = cheerio.load(html); //采用cheerio解析页面
resolve($);
})
})
})
};
/**
* @method 获取所有省
* @param initUrl
* @returns {Promise.<void>}
*/
async function getProvince(initUrl) {
console.time("计时器");
let subUrlArray = [];
await httpGet(initUrl).then(($)=>{
let provincetds = $(".provincetr td");
provincetds.each((i)=> {
let subUrl = provincetds.eq(i).find("a").attr("href");
let name = provincetds.eq(i).find("a").text();
dataSource.push({
province: name,
cityArray: []
});
//将函数参数放入队列
subUrlArray.push({
url: url,
subUrl: subUrl,
j: i
});
})
});
//await的上下文async
// console.log(subUrlArray)
for(let i=0;i<subUrlArray.length;i++){
console.log("进入"+dataSource[i].province);
await startRequest(url,subUrlArray[i].subUrl,i);
//根据省生成文件
let fileName = dataSource[i].province;
let text = JSON.stringify(dataSource[i].cityArray);
await createTxt(fileName,text);
}
console.timeEnd("计时器");
}
/**
* @method 根据省查询该省下面的所有市
* @param url
* @param subUrl
* @param i
* @returns {Promise}
*/
async function startRequest(url,subUrl,i){
let subUrlArray = [];
await httpGet(url+subUrl).then(($)=>{
let citytr = $(".citytr");
//保存省市和地址
citytr.each(function(index){
let cityNum = $(this).find("td").eq(0).find("a").text();
let name = $(this).find("td").eq(1).find("a").text();
let cityUrl = $(this).find("td").eq(0).find("a").attr("href");
dataSource[i]["cityArray"].push({
city : name,
cityNum : cityNum,
countryArray : []
});
//将函数参数放入队列
let countryUrl = url.replace(/.html/,"");
subUrlArray.push({
countryUrl: countryUrl,
subUrl: cityUrl,
});
});
});
for(let j=0;j<subUrlArray.length;j++){
let url = subUrlArray[j].countryUrl;
let subUrl = subUrlArray[j].subUrl;
await startCounty(url,subUrl,i,j);
}
}
/**
* @method 查询市区下面的区县
* @param url
* @param subUrl
* @param proIndex
* @param cityIndex
* @returns {Promise.<void>}
*/
async function startCounty(url,subUrl,proIndex,cityIndex){
let subUrlArray = [];
//console.log("进入区县",url+subUrl)
await httpGet(url+subUrl).then(($)=>{
let countytr = $(".countytr");
//保存区县和地址
countytr.each(function(i){
//console.log("区县",i)
let countyNum = $(this).find("td").eq(0).find("a").text();
let name = $(this).find("td").eq(1).find("a").text();
let areaurl = $(this).find("td").eq(0).find("a").attr("href");
dataSource[proIndex]["cityArray"][cityIndex]["countryArray"].push({
county : name,
countyNum : countyNum,
areaArray : [],
});
let newUrl = subUrl.split(/\//)[0]+"/"+areaurl;
if(areaurl){
subUrlArray.push({
newUrl : newUrl,
index : i
});
}
});
});
for(let i=0;i<subUrlArray.length;i++){
let data = subUrlArray[i];
await getTree(url,data.newUrl,proIndex,cityIndex,data.index);
}
}
/**
* @method 根据区县爬取街道
* @param url
* @param subUrl
* @param proIndex
* @param cityIndex
* @param countyIndex
* @returns {Promise.<void>}
*/
async function getTree(url,subUrl,proIndex,cityIndex,countyIndex){
let subUrlArray = [];
//console.log("街道",url+subUrl)
await httpGet(url+subUrl).then(($)=>{
let towntr = $(".towntr");
//console.log("towntr",towntr.length)
//保存区县和地址
towntr.each(function(i){
let countyNum = $(this).find("td").eq(0).find("a").text();
let name = $(this).find("td").eq(1).find("a").text();
let newurl = $(this).find("td").eq(0).find("a").attr("href");
dataSource[proIndex]["cityArray"][cityIndex]["countryArray"][countyIndex]["areaArray"].push({
area : name,
areaNum : countyNum,
jwhArray : [],
});
let reUrl = subUrl.split(/\//)[0]+"/"+subUrl.split(/\//)[1]+"/"+newurl;
if(newurl){
subUrlArray.push({
reUrl : reUrl,
index : i
})
}
});
});
for(let i=0;i<subUrlArray.length;i++){
let data = subUrlArray[i];
await getJwh(url,data.reUrl,proIndex,cityIndex,countyIndex,data.index);
}
}
/**
* @method 根据街道爬取办事处
* @param url
* @param subUrl
* @param proIndex
* @param cityIndex
* @param countyIndex
* @param areaIndex
* @returns {Promise.<void>}
*/
async function getJwh(url,subUrl,proIndex,cityIndex,countyIndex,areaIndex){
let subUrlArray = [];
//console.log("getJwh",url+subUrl);
await httpGet(url+subUrl).then(($)=>{
let villagetr = $(".villagetr");
//console.log(villagetr.length);
villagetr.each(function(i){
let countyNum = $(this).find("td").eq(0).text();
let name = $(this).find("td").eq(2).text();
dataSource[proIndex]["cityArray"][cityIndex]["countryArray"][countyIndex]["areaArray"][areaIndex]["jwhArray"].push({
jwh : name,
jwhNum : countyNum,
});
//console.log("name",name)
});
})
}
getProvince(initUrl);
