JAVA——三级联动 省 市 区

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login.jsp首页


<%@ page contentType="text/html;charset=UTF-8" language="java" %>
<html>
<head>
    <title>Title</title>
    <script type="text/javascript" src="js/jquery-3.6.0.js"></script>

</head>
<body>
<script>
    $(function () {
        $.ajax({
            type:"get",//类型
            url:"findprovince",//地址
            dataType:"json",//数据类型
            success:function (data) {//回调函数 data的值就是从后端发送过来的json格式的字符串
                //拿到当前省份的元素对象
                var obj=$("#province");
                for ( var  i = 0; i < data.length;i++){
                    var ob="<option value='"+data[i].pid+"'>"+data[i].pname+"</option>";
                    obj.append(ob);

                }

            }
        });
    });
</script>

<select name="province" id="province">
    <option value="0">请选择</option>
</select>省
<select name="city" id="city">
    <option value="0">请选择</option>
</select>市
<select name="street" id="street">
    <option value="0">请选择</option>
</select>区
<script>
    $("#province").change(function () {
        $("#city option").remove();
        $.ajax({
            type: "get",
            url: "findcitybypid?id="+$("#province").val(),
            dataType: "json",
            success:function (data) {
                var obj=  $("#city");
                for (var i=0;i<data.length;i++){
                    var  ob= "<option value='"+data[i].cid+"'>"+data[i].cname+"</option>"
                    obj.append(ob)
                }
            }
        });
    });
</script>
<script>
        $("#city").change(function () {
            $("#street option").remove();
            $.ajax({
                type:"get",
                url:"findstreetbysid?id="+$("#city").val(),
                dataType: "json",
            success:function (data) {
                var obj=  $("#street");
                for (var i=0;i<data.length;i++){
                    var  ob= "<option value='"+data[i].sid+"'>"+data[i].sname+"</option>"
                    obj.append(ob)
                }
            }
        });
    });
</script>

</body>
</html>

dao层 的接口
省份 的dao的接口ProvinceInfoDao

package cn.hp.dao;

import cn.hp.model.Province;

import java.util.List;

public interface ProvinceInfoDao {
    public List<Province> findAll();

}

市的dao的接口CityInfoDao

package cn.hp.dao;

import cn.hp.model.City;
import cn.hp.model.Province;

import java.util.List;

public interface CityInfoDao {
    public List<City> findAllCity(int pid);
}

区的dao的接口StreetDao

package cn.hp.dao;

import cn.hp.model.Street;

import java.util.List;

public interface StreetDao {
    public List<Street> findAllStreet(int cid);
}

impl层 dao的实现类
省份dao的实现类ProvinceInfoDaoImpl

package cn.hp.dao;

import cn.hp.model.Province;
import cn.hp.util.DBHelper;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

//接口实现类
public class ProvinceInfoDaoImpl implements ProvinceInfoDao {
    @Override
    public List<Province> findAll() {
        Connection conn = DBHelper.getConn();
        List<Province> list=new ArrayList<Province>();
        String sql="select * from province";
        try {
            PreparedStatement ps=conn.prepareStatement(sql);//预编译当前的sql语句
            ResultSet rs = ps.executeQuery();
            while (rs.next()){
                Province p=new Province();//实例化当前省份
                p.setPid(rs.getInt(1));
                p.setPname(rs.getString(2));
                list.add(p);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }
}

市dao的实现类CityInfoDaoImpl

package cn.hp.dao;

import cn.hp.model.City;
import cn.hp.util.DBHelper;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class CityInfoDaoImpl implements CityInfoDao {
    @Override
    public List<City> findAllCity(int pid) {
        Connection conn = DBHelper.getConn();
        List<City> list=new ArrayList<City>();
        String sql="select * from city where pid=?";
        try {
            PreparedStatement ps=conn.prepareStatement(sql);//预编译当前的sql语句
            ps.setInt(1,pid);
            ResultSet rs = ps.executeQuery();
            while (rs.next()){
                City c=new City();//实例化当前省份
                c.setCid(rs.getInt(1));
                c.setCname(rs.getString(2));
                c.setPid(rs.getInt(3));
                list.add(c);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }
}

区县dao的实现类StreetDaoImpl

package cn.hp.dao;

import cn.hp.model.Street;
import cn.hp.util.DBHelper;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;
import java.util.ArrayList;
import java.util.List;

public class StreetDaoImpl implements StreetDao {
    @Override
    public List<Street> findAllStreet(int cid) {
        Connection conn= DBHelper.getConn();
        List<Street> list= new ArrayList<Street>();
        String sql="select * from street where cid =?";
        try {
            PreparedStatement ps= conn.prepareStatement(sql);//预编译当前的sql语句
            ps.setInt(1,cid);
            ResultSet rs=  ps.executeQuery();
            while (rs.next()){
                Street s= new Street();//实例化当前区
                s.setSid(rs.getInt(1));
                s.setSname(rs.getString(2));
                s.setCid(rs.getInt(3));

                list.add(s);
            }
        } catch (SQLException e) {
            e.printStackTrace();
        }
        return list;
    }

}

model层 实体类
省 Province

package cn.hp.model;

public class Province {
    private int pid;
    private String pname;

    

    public Province(int pid, String pname) {
        this.pid = pid;
        this.pname = pname;
    }

    public Province() {
    }

    public int getPid() {
        return pid;
    }

    public void setPid(int pid) {
        this.pid = pid;
    }

    public String getPname() {
        return pname;
    }

    public void setPname(String pname) {
        this.pname = pname;
    }
}

市City

package cn.hp.model;

public class City {
    private int cid;
    private String cname;
    private int pid;



    public City(int cid, String cname, int pid) {
        this.cid = cid;
        this.cname = cname;
        this.pid = pid;
    }

    public City() {
    }

    public int getCid() {
        return cid;
    }

    public void setCid(int cid) {
        this.cid = cid;
    }

    public String getCname() {
        return cname;
    }

    public void setCname(String cname) {
        this.cname = cname;
    }

    public int getPid() {
        return pid;
    }

    public void setPid(int pid) {
        this.pid = pid;
    }
}

区Street

package cn.hp.model;

public class Street {
    private int sid;
    private String sname;
    private int cid;

    public int getSid() {
        return sid;
    }

    public void setSid(int sid) {
        this.sid = sid;
    }

    public String getSname() {
        return sname;
    }

    public void setSname(String sname) {
        this.sname = sname;
    }

    public int getCid() {
        return cid;
    }

    public void setCid(int cid) {
        this.cid = cid;
    }

    public Street(int sid, String sname, int cid) {
        this.sid = sid;
        this.sname = sname;
        this.cid = cid;
    }

    public Street() {
    }
}

servlet层
省 ProvincServlet

package cn.hp.servlet;

import cn.hp.dao.ProvinceInfoDao;
import cn.hp.dao.ProvinceInfoDaoImpl;
import cn.hp.model.Province;
import com.alibaba.fastjson.JSONObject;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/findprovince")
public class FindProvinceServlet extends HttpServlet {

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //编码格式
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        ProvinceInfoDao pid=new ProvinceInfoDaoImpl();
        List<Province> plist =pid.findAll();
        //把这个省份的集合转换成json格式的数据发送到前端页面
        response.getWriter().write(JSONObject.toJSONString(plist));
    }
}

市CityPidServlet

package cn.hp.servlet;

import cn.hp.dao.CityInfoDao;
import cn.hp.dao.CityInfoDaoImpl;
import cn.hp.model.City;
import com.alibaba.fastjson.JSONObject;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/findcitybypid")
public class FindCityByPidServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //编码格式
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        String id = request.getParameter("id");
        CityInfoDao cid=new CityInfoDaoImpl();
        List<City> list = cid.findAllCity(Integer.parseInt(id));
        //把城市的集合转换成json格式的字符串发送到前端页面
        response.getWriter().write(JSONObject.toJSONString(list));
    }

}

区CitySidServlet

package cn.hp.servlet;

import cn.hp.dao.StreetDao;
import cn.hp.dao.StreetDaoImpl;
import cn.hp.model.Street;
import com.alibaba.fastjson.JSONObject;

import javax.servlet.ServletException;
import javax.servlet.annotation.WebServlet;
import javax.servlet.http.HttpServlet;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;
import java.io.IOException;
import java.util.List;

@WebServlet("/findstreetbysid")
public class FindCityBySidServlet extends HttpServlet {
    @Override
    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {
        //编码格式
        request.setCharacterEncoding("utf-8");
        response.setContentType("text/html;charset=utf-8");
        String id = request.getParameter("id");
        StreetDao sid=new StreetDaoImpl();
        List<Street> slist = sid.findAllStreet(Integer.parseInt(id));
        response.getWriter().write(JSONObject.toJSONString(slist));
    }
}

util层工具类

package cn.hp.util;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.SQLException;

public class DBHelper {
	private static String Driver = "com.mysql.jdbc.Driver";
	private static String Url = "jdbc:mysql://localhost:3306/provinces?characterEncoding=utf8";
	private static String user = "root";
	private static String pwd = "123456";
	public static Connection conn;

	public static Connection getConn() {
		try {
			Class.forName(Driver);
			conn = DriverManager.getConnection(Url, user, pwd);
		} catch (Exception e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
		return conn;
	}


	public static void getClose() {
		try {
			if (conn != null) {
				conn.close();
			}
		} catch (SQLException e) {
			// TODO Auto-generated catch block
			e.printStackTrace();
		}
	}


	public static void main(String[] args) {
		System.out.println(getConn());
		if (getConn()!=null) {
			System.out.println("���ӳɹ�");
		}
	}
}

数据库信息

CREATE database provinces CHARACTER  set utf8;
use provinces; 


CREATE table  province (
pid INT PRIMARY KEY  auto_increment,
pname varchar(20)
);


INSERT into province VALUES (null,"河南省");
INSERT into province VALUES (null,"山东省");
INSERT into province VALUES (null,"河北省");

CREATE table  city (
cid INT PRIMARY KEY  auto_increment,
cname varchar(20),
pid int  
);

-- 河南省
INSERT into city VALUES (null,"郑州市",1);
INSERT into city VALUES (null,"开封市",1);
INSERT into city VALUES (null,"洛阳市",1);

-- 山东
INSERT into city VALUES (null,"济南市",2);
INSERT into city VALUES (null,"青岛市",2);
INSERT into city VALUES (null,"淄博市",2);

-- 河北
INSERT into city VALUES (null,"石家庄市",3);
INSERT into city VALUES (null,"唐山市",3);
INSERT into city VALUES (null,"秦皇岛市",3);



CREATE table  street (
sid INT PRIMARY KEY  auto_increment,
sname varchar(20),
cid int 
);


-- 郑州市
INSERT into street VALUES (null,"中原区",1);
INSERT into street VALUES (null,"二七区",1);
INSERT into street VALUES (null,"管城回族区",1);

-- 开封市
INSERT into street VALUES (null,"龙亭区",2);
INSERT into street VALUES (null,"顺河回族区",2);
INSERT into street VALUES (null,"鼓楼区",2);

-- 洛阳市
INSERT into street VALUES (null,"汝阳",3);
INSERT into street VALUES (null,"宜阳",3);
INSERT into street VALUES (null,"洛宁",3);

-- 济南市
INSERT into street VALUES (null,"商河县",4);
INSERT into street VALUES (null,"济阳县",4);
INSERT into street VALUES (null,"平阴县",4);
-- 青岛市
INSERT into street VALUES (null,"七区五市",5);
INSERT into street VALUES (null,"市南区",5);
INSERT into street VALUES (null,"市北区",5);
-- 淄博市 
INSERT into street VALUES (null,"博山",6);
INSERT into street VALUES (null,"周村",6);
INSERT into street VALUES (null,"临淄",6);

-- 石家庄市
INSERT into street VALUES (null,"正定县",7);
INSERT into street VALUES (null,"行唐县",7);
INSERT into street VALUES (null,"灵寿县",7);

-- 唐山市
INSERT into street VALUES (null,"乐亭县",8);
INSERT into street VALUES (null,"迁西县",8);
INSERT into street VALUES (null,"玉田县",8);

-- 秦皇岛市
INSERT into street VALUES (null,"青龙满族自治县",9);
INSERT into street VALUES (null,"昌黎县",9);
INSERT into street VALUES (null,"卢龙县",9);

实现效果

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