概述

通过地址的经纬度在GIS中我们称之为地理编码，与之对应的就是通过经纬度获取地址，被称为逆地理编码。不论是地理编码还是逆地理编码，在我们实际的工作、学习中都会有很多的场景，本文讲述的在node环境下，通过高德API实现经纬度数据的获取。

效果

爬虫中 爬虫结束 返回的结果 实现效果

实现

在本示例中，首先将地址数据导入到数据库中，同时将获取到的经纬度数据存储在数据库中。实现代码如下：

const pgConfig = require('./model/pgConfig');
const pg = require('pg');
const pool = new pg.Pool(pgConfig);
let request = require("./utils/request");
const chalk = require('chalk');

// 申请的key
const aKey = {
  0: '申请的key1',
  1: '申请的key2',
  2: '申请的key3'
}
const aUrl = 'https://restapi.amap.com/v3/geocode/geo'

/**
 * 获取随机数
 * @param minNum
 * @param maxNum
 * @return {number}
 */
function getRandom(minNum = 80,maxNum = 200){
  switch(arguments.length){
    case 1:
      return parseInt(Math.random()*minNum+1,10);
    case 2:
      return parseInt(Math.random()*(maxNum-minNum+1)+minNum,10);
    default:
      return 0;
  }
}

/**
 * json
 * @param url
 * @return {Promise<unknown>}
 */
function getJson(url) {
  return new Promise(resolve => {
    request(url).then(res => {
      resolve(res)
    });
  })
}

async function getAddressLonLat(address) {
  try {
    const urlFull = `${aUrl}?address=${address}&key=${aKey[getRandom(0, 2)]}`
    let res = await getJson(urlFull)
    res = JSON.parse(res.toString())
    const geocodes = res['geocodes']
    if(geocodes && geocodes.length > 0) {
      const { location } = geocodes[0]
      return location
    }
  } catch (e) {
    console.debug(e)
  }
}

function startSpider(table) {
  console.time(table)
  let index = 0
  let count = 0
  let rowsData = []
  let flag = 0
  let updateSql = {
    id: [],
    lonlat: []
  }

  const getLocation = () => {
    flag = setTimeout(() => {
      // 进度输出
      if((index > 0 && index % 20 === 0) || index === count) {
        console.log(`${table}：----------${index}`)
        if(updateSql.id.length > 0) {
          let val = ''
          updateSql.id.forEach((id, index) => {
            val += ` WHEN ${id} THEN '${updateSql.lonlat[index]}' `
          })
          let sqlUpdate = `
            UPDATE ${table}
            SET lonlat = CASE id
                    ${val}
                END
            WHERE id IN (${updateSql.id.join(',')});
        `
          pool.query(sqlUpdate, (_isErr, _res) => {
            if(_isErr) console.error(`${table}----------数据库更新错误`)
            index++
            getLocation()
            if(index >= count) {
              clearTimeout(flag)
              console.timeEnd(table)
              console.log(chalk.green(`----------${table}结束处理----------`))
              process.exit(1);// 退出进程
            }
          })
        } else {
          if(index >= count) {
            clearTimeout(flag)
            console.timeEnd(table)
            console.log(chalk.green(`----------${table}结束处理----------`))
            process.exit(1);// 退出进程
          }
          index++
          getLocation()
        }
      } else {
        const id = rowsData[index] && rowsData[index].id
        if(id) {
          let sql = `select reg_location as loc, company_name as name
                   from ${table} where id=${id};`
          pool.query(sql, (isErr, res) => {
            if(isErr) console.error('数据库查询错误')
            else {
              const address = [res.rows[0].loc, res.rows[0].name]
              getAddressLonLat(address.join('')).then(location => {
                if(location) {
                  updateSql.id.push(id)
                  updateSql.lonlat.push(location)
                }
                index++
                getLocation()
              })
            }
          });
        }

      }
    }, getRandom())
  }
  // 查询条数
  const countSql = `select id from ${table} where lonlat  = '' order by id;`
  pool.query(countSql, (isErr, res) => {
    if(isErr) console.error('数据库查询错误')
    else {
      const rows = res.rows
      rowsData = rows
      count = rows.length
      console.log(chalk.red(`----------开始处理${table}，共${count}条记录----------`))
      getLocation()
    }
  });
}

pool.connect(isError => {
  if(isError) console.error(chalk.red('数据库连接错误'))
  startSpider('company_2006')
})

request代码如下：

const request = require("request");

function handleRequestByPromise(url, options = {}) {
  options.url = encodeURI(url)
  let op = Object.assign(
    {},
    {
      url: "",
      method: "GET",
      encoding: null,
      header: {
        "User-Agent":
          "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36",
        Referer: "https://www.meituri.com"
      }
    },
    options
  );

  if (op.url === "") {
    throw new Error("请求的url地址不正确");
  }

  const promise = new Promise(function(resolve, reject) {
    request(op, (err, response, body) => {
      if (err) reject(err);
      if (response && response.statusCode === 200) {
        resolve(body);
      } else {
        reject(`请求${url}失败!`);
      }
    });
  });

  return promise;
}

module.exports = handleRequestByPromise

pgConfig代码如下：

const config = {
  host: 'ip',
  user: 'user',
  database: 'database',
  password: 'password',
  port: 5432,
  // 扩展属性
  max: 40, // 连接池最大连接数
  idleTimeoutMillis: 3000, // 连接最大空闲时间 3s
};

module.exports = config;

说明：

1. aKey设置了多个，是为了防止账户被封；
2. 在获取经纬度数据的时候设置了80-200ms的随机延迟，也是为了防止账户被封；