公交换乘一站算法

 

公交换乘一站算法busTransfer
/**
* 公交换乘一站的算法思想：
* （注意：车次信息、站点信息、公交信息是等价的都是以HashMap的形式存储信息）
* 1.从数据库中获得所有公交信息存储到ArrayList，每个具体信息的元数据有三个：
* 公交车次、公交站点、该公交站点距离该公交车次的始发站点的站数，具体信息用HashMap保存
* 2.然后把公交信息数据进行结构化，把所有公交站点抽出，再把每一个站点对应的所有车次抽出
* 与其一一对应，单一的车次信息用HashMap存储，站点对应的所有车次信息用ArrayList存储，
* 所有的站点有经过站点的车次信息用HashMap存储
* 3.根据查询要求，分别从结构化以后的公交信息数据中找到，经过出发地的所有车次，经过目的地
* 的所有车次，然后在分别遍历每个车次，筛选出符合要求的中转站点，筛选规则是：每查询出一个
* 站点时，得到该站点距离该站点对应车次的始发站的站数，如果这个站数小于查询站点距离该车次的始
* 发站的站数，那么就符合规则，便把该站点信息保存到符合站点的ArrayList中，反之亦然
* 4.分别得到查询条件中出发地和目的地的中转站点信息（中转站点信息存储在ArrayList中），然
* 后遍历两个中转站点信息的集合，得到最终的具体中转信息（最终中转信息也是用ArrayList存储）
*/
package bustransfer;

import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.ResultSet;
import java.sql.ResultSetMetaData;
import java.sql.SQLException;
import java.sql.Statement;
import java.util.ArrayList;
import java.util.Iterator;
import java.util.List;
import java.util.HashMap;
import java.util.Map;

public class BusTransfer {

        private String start = null;// 出发地

        private String whither = null;// 目标地

        private List schedule = null;// 用于缓存列车时刻表。

        private HashMap <String, ArrayList> stationsOfLine = null; // 所有公交线路，每个list存储该线路经过的所有车站。

        private HashMap <String, ArrayList> linesOfStation = null;// 所有车站，每个list中存储通过该车站的所有车次。

        // private ArrayList <String> startLine = new ArrayList <String>();//
        // 途经出发地的所有车次。

        // private ArrayList <String> whitherLine = new ArrayList <String>();//
        // 途经目的地的所有车次。

        private ArrayList <Map> firLineStaList = new ArrayList <Map>();

        private ArrayList <Map> secLineStaList = new ArrayList <Map>();

        public BusTransfer(String start, String whither) {
                this.start = start;
                this.whither = whither;

                try {
                        this.schedule = this
                                        .executeQuery("select busLine,up,stationNo from bus_stations");
                } catch (Exception e) {
                        // TODO Auto-generated catch block
                        System.out.println("读取数据库出错");
                        e.printStackTrace();
                }
                stationsOfLine = this.getStationsOfLine();
                linesOfStation = this.getLinesOfStation();
        }

        private HashMap <String, ArrayList> getStationsOfLine() {
                HashMap map = new HashMap();// 用于 临时存储从schedule中取出的HashMap.
                ArrayList <Map> line = null;// 每个list存储一个车次的相关车站信息。
                String buffer = "a";// 缓存站名。
                String temp = null;// 临时存储每次迭代取出的站名，用于与buffer站名比较。
                HashMap <String, ArrayList> stationsGroupByLine = new HashMap <String, ArrayList>();// 存储以车次分组後的车站的list

                Iterator it = schedule.iterator(); // 迭代器
                while (it.hasNext()) {
                        map = (HashMap) it.next();

                        temp = (String) map.get("busLine");
                        if (stationsGroupByLine.containsKey(temp)) {
                                line = stationsGroupByLine.get(temp);
                                buffer = (String) ((Map) line.get(0)).get("busLine");
                        }
                        if (buffer.equals(temp)) {
                                line.add(map);// 将同一车次的车站放入一个list中

                        } else {
                                if (line != null && !line.isEmpty()) {
                                        stationsGroupByLine.put(buffer, line);// 将由车次分组后的车站构成的list存入一个map
                                }
                                line = new ArrayList <Map>(); // line重新引用一个新构造的list，以供存储同一车站的车次。
                                line.add(map);// 将同一车次的车站放入刚刚构造的空list中
                        }
                        buffer = temp;// 缓存当前操作的车次。
                }
                return stationsGroupByLine;
        }

        private HashMap getLinesOfStation() {
                HashMap map = new HashMap();// 用于 临时存储从schedule中取出的HashMap.
                ArrayList <Map> station = null;// 每个list存储一个经过该车站的相关车次信息。
                String buffer = "a";// 缓存车次。
                String temp = null;// 临时存储每次迭代取出的车次，用于与buffer车次比较。
                HashMap <String, ArrayList> linesGroupBystation = new HashMap <String, ArrayList>();// 存储以车站分组後的车次的list

                Iterator it = schedule.iterator(); // 迭代器
                while (it.hasNext()) {
                        map = (HashMap) it.next();

                        temp = (String) map.get("up");
                        if (linesGroupBystation.containsKey(temp)) {
                                // station存储temp车次对应的站点信息
                                station = linesGroupBystation.get(temp);
                                // 从station中取出已经放入linesGroupBystation车站信息，缓存改车站的名字
                                // 与刚取出的Map中存储到车站信息进行比较
                                buffer = (String) ((Map) station.get(0)).get("up");
                        }
                        if (buffer.equals(temp)) {
                                // 如果station中几经存在该站点信息，那么，本站和station中存储到是同一站，所以
                                // 将同一车次的车站放入一个list中
                                station.add(map);

                        } else {
                                if (station != null && !station.isEmpty()) {
                                        // 将由车次分组后的车站构成的list存入一个map
                                        linesGroupBystation.put(buffer, station);
                                }
                                // line重新引用一个新构造的list，以供存储经过另一车站的所有车次
                                station = new ArrayList <Map>();
                                station.add(map);// 将同一车次的车站放入刚刚构造的空list中
                        }
                        buffer = temp;// 缓存当前操作的车次。
                }
                return linesGroupBystation;
        }

  /**
        * 站点筛选规则：把符合规则的站点添分别放入
        *
        * @param startSta
        * @param whitherSta
        */
        private void getStationsInLine(String startSta, String whitherSta) {
                // 获得经过初始站点的所有公交车次
                ArrayList firTrainLine = linesOfStation.get(startSta);
                // 获得经过所有目的站点的公交车次
                ArrayList secTrainLine = linesOfStation.get(whitherSta);

                ArrayList station;
                HashMap line = null;
                int transferStaNo = 0;
                // String stationName = null;
                String trainNo = "";

                if (firTrainLine != null) {
                        Iterator firIt = firTrainLine.iterator();
                        while (firIt.hasNext()) {
                                // 取出一个存储车站信息HashMap
                                line = (HashMap) firIt.next();
                                // 取出车次信息
                                trainNo = (String) line.get("busLine");
                                transferStaNo = (Integer) line.get("stationNo");

                                // 取出车次trainNo经过的所有站点信息
                                station = stationsOfLine.get(trainNo);
                                Iterator it = station.iterator();
                                while (it.hasNext()) {

                                        Map map = (Map) it.next();// trainNo's map.
                                        int i = (Integer) map.get("stationNo");
                                        // 筛选站点规则：如果该站点距离初始站点距离比出发站点的距离初始站点的距离大，那么就把该站点存储到
                                        // firLineStaList,反之就做反车了，所以那些站点不必加入firLineStaList中
                                        if (i > transferStaNo) {
                                                //
                                                firLineStaList.add(map);
                                        }
                                }
                        }
                }

                if (secTrainLine != null) {
                        Iterator secIt = secTrainLine.iterator();
                        while (secIt.hasNext()) {
                                line = (HashMap) secIt.next();
                                trainNo = (String) line.get("busLine");
                                transferStaNo = (Integer) line.get("stationNo");

                                station = stationsOfLine.get(trainNo);
                                Iterator it = station.iterator();
                                while (it.hasNext()) {

                                        Map map = (Map) it.next();
                                        int i = (Integer) map.get("stationNo");

                                        if (i < transferStaNo) {

                                                secLineStaList.add(map);
                                        }
                                }
                        }
                }
        }

        /**
        *
        * create date:2008-5-19 author:Administrator
        *
        * @return
        */
        private ArrayList <Map> checkCrossLine() {

                ArrayList <Map> crossLineList = new ArrayList <Map>();// 相交线路的集合,即是所有的换乘方法的集合
                ArrayList <Map> lsStart = firLineStaList;// 经过起点站的所有车次的经停站站信息。
                ArrayList <Map> lsEnd = secLineStaList;// 经过目的站的所有车次的经停站站信息。

                if (lsStart != null && !lsStart.isEmpty() && lsEnd != null
                                && !lsEnd.isEmpty()) {

                        for (Map <String, String> mapStart : lsStart) {
                                for (Map <String, String> mapEnd : lsEnd) {
                                        if (IsInTheSameCity(mapStart.get("up"), mapEnd.get("up"))) {

                                                // 将相交线路信息存入crossLine，存储某一个具体的换乘方法
                                                Map <String, String> crossLine = new HashMap <String, String>(
                                                                4, 0.8f);

                                                // 把第一次要做到车次放如crossLine
                                                crossLine.put("firstLine", mapStart.get("busLine"));
                                                // 把要换乘的车次放入到crossLine
                                                crossLine.put("secondLine", mapEnd.get("busLine"));
                                                // 把中转站点放入到crossLine
                                                crossLine.put("transferSta", mapEnd.get("up"));

                                                // crossLine.put("transferSta",(String)startInf.get("up"));
                                                // 将包含相交线路信息的HashMap存入List
                                                // 也即是把具体某个换乘方法放入crossLineList
                                                crossLineList.add(crossLine);
                                        } else {
                                                continue;
                                        }
                                }
                        }

                } else {
                        crossLineList = null;
                }

                return crossLineList;
        }

        private boolean IsInTheSameCity(String station1, String station2) {

                if (station1.contains(station2) | | station2.contains(station1)) {
                        // System.out.println(station1+"#########"+station2);
                        return true;
                } else {
                        return false;
                }

        }

        public ArrayList <Map> getSchemaOfTransfer() {
                this.getStationsInLine(this.start, this.whither);
                return this.checkCrossLine();
        }

        public static void main(String[] args) {
                BusTransfer tb = new BusTransfer("前门", "天安门西");
                // tb.getSchemaOfTransfer();
                for (Map map : tb.getSchemaOfTransfer()) {
                        System.out.println(map);
                        System.out.println("您好，您可以先乘坐 " + map.get("firstLine") + " 到 "
                                        + map.get("transferSta") + " 然后换乘 " + map.get("secondLine")
                                        + " 便可到达，不要错过站吆 ！");
                }

                // System.out.println(tb.secLineStaList.size());
        }

 private Connection getConnection() {
                Connection con = null;
                String url = "jdbc:mysql://127.0.0.1:3306/souwhat?autoReconnect=true&useUnicode=true&characterEncoding=GBK&amp;mysqlEncoding=GBK";
                String user = "root";
                String psWord = "";
                try {
                        Class.forName("com.mysql.jdbc.Driver");
                } catch (ClassNotFoundException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                        System.out.println("The Exception at load the Driver");
                }
                try {
                        con = DriverManager.getConnection(url, user, psWord);
                } catch (SQLException e) {
                        // TODO Auto-generated catch block
                        e.printStackTrace();
                        System.out.println("The Exception at creat the connection");
                }
                return con;
        }

        private void closeConnection(Connection conn) throws Exception {
                if (conn != null) {
                        conn.close();
                }
        }

        private List executeQuery(String sql) throws Exception {
                // System.out.println("executeQuery(sql): " + sql);
                List list = new ArrayList();
                Connection conn = null;
                Statement stmt = null;
                ResultSet rs = null;
                try {
                        conn = getConnection();
                        stmt = conn.createStatement();

                        System.out.println(sql);

                        rs = stmt.executeQuery(sql);

                        ResultSetMetaData rsmd = rs.getMetaData();
                        while (rs.next()) {
                                Map map = new HashMap();
                                for (int i = 1; i <= rsmd.getColumnCount(); i++) {
                                        // 每一行所有列存入HashMap中
                                        map.put(rsmd.getColumnName(i), rs.getObject(i));
                                }
                                // 所有行存入List中
                                list.add(map);
                        }
                } catch (Exception e) {
                        System.out.println("数据库查询出错!");
                        e.printStackTrace();
                } finally {
                        if (rs != null)
                                rs.close();
                        closeConnection(conn);
                }
                return list;
        }
}