其实express就是为了提供数据，根据条件查找信息

没有添加美化样式，自己可以优化css样式。

1、html界面

<h4 type="info">省市县三级联动 {{address}}</h4>
<p>
    <input type="text" [(ngModel)]="address" name="address" class="form-control" (click)="provinceClick()" placeholder="请选择城市"/>
</p>
<div class="row">
    <div class="col-sm-12">
      <span *ngFor="let item of provinceData" (click)="provinceChange(item.ProID,item.name)">{{item.name}}<span class="text-primary"> | </span></span>
    </div>
</div>
<br/>
<div class="row">
    <div class="col-sm-12" >
      <span *ngFor="let item of cityData" (click)="cityChange(item.CityID,item.name)">{{item.name}}<span class="text-primary"> | </span></span>
    </div>
</div>
<br/>
<div class="row">
    <div class="col-sm-12">
      <span *ngFor="let item of countryData" (click)="countryChange(item.DisName)">{{item.DisName}}<span class="text-primary"> | </span></span>
    </div>
</div>

2、和新ng2代码

import {Component,OnInit} from "@angular/core";
import {HttpServer} from "../servers/http.server";
import {URLSearchParams} from "@angular/http";
@Component({
  selector: "sport-home",templateUrl: "../templates/home.component.html",providers: []
})
export class HomeComponent {
  address: string;
  province: string;
  city: string;
  country: string;

  provinceData: Array<Object>;
  cityData: Array<Object>;
  countryData: Array<Object>;

  constructor(public httpServer:HttpServer) {
    this.province = "";
    this.city = "";
    this.country = "";

    this.provinceData = [];
    this.cityData = [];
    this.countryData = [];

    this.address = "";

  }

  // 获取省份
  provinceClick() {
    var url = "http://localhost:3000/province";
    var params = new URLSearchParams();
    params.set("callback","JSONP_CALLBACK");
    this.httpServer.jsonpGet(url,params).subscribe(res=> {
      console.log(res);
      this.provinceData = res;
    });
    this.address = "";
  }
  // 单机省份
  provinceChange(ProID,name) {
    var url = "http://localhost:3000/city";
    var params = new URLSearchParams();
    params.set("ProID",ProID);
    params.set("callback","JSONP_CALLBACK");

    this.httpServer.jsonpGet(url,params).subscribe(res=> {
      console.log(res);
      this.cityData = res;
    });

    this.province = name;

    this.address = this.province;
  }
  // 单机市
  cityChange(CityID,name) {
    var url = "http://localhost:3000/country";
    var params = new URLSearchParams();
    params.set("CityID",CityID);
    params.set("callback",params).subscribe(res=> {
      console.log(res);
      this.countryData = res;

      this.city = name;

      this.address = this.province + "," + this.city;
    })
  }
  countryChange(name) {
    this.country = name;
    this.address = this.province + "," + this.city + "," + this.country;

    // 最后一步选中后,隐藏数据。
    this.provinceData = [];
    this.cityData = [];
    this.countryData = [];
  }
}

3、封装的获取数据的服务http.server.ts

import {Injectable} from "@angular/core";
import {Http,Jsonp} from "@angular/http";
import "rxjs/add/operator/map";
@Injectable()
export class HttpServer {
  constructor(public http:Http,public jsonp:Jsonp) {

  }

  httpGet(url,params) {
    return this.http.get(url,{search: params}).map(result=>result.json());
  }

  httpPost(url,params) {
    return this.http.post(url,{search: params}).map(result=>result.json());
  }

  jsonpGet(url,params) {
    return this.jsonp.get(url,{search: params}).map(result=>result.json());
  }
}

4、express的核心代码

province.js

var express = require("express");
var router = express.Router();
var connection = require("../conf/db");

router.get("/",function (req,res,next) {
    connection("select * from province",function (err,rows,fields) {
        console.log(rows);
        res.jsonp(rows);
    })
});
module.exports = router;

city.js

var express = require("express");
var router = express.Router();
var connection = require("../conf/db");

router.get("/",next) {
    var proId = req.query.ProID;
    connection("select * from city where ProID='" + proId + "'",fields) {
        console.log(rows);
        res.jsonp(rows);
    })
});
module.exports = router;

country.js

var express = require("express");
var router = express.Router();
var connecion = require("../conf/db");

router.get("/",next) {
    var CityID = req.query.CityID;
    connecion("select * from country where CityID = '" + CityID + "'",fields) {
        console.log(rows);
        res.jsonp(rows);
    })
});

module.exports = router;