今日共同报告-10-安卓端实现最短路径查询

今日共同报告-10

今天我完成了们完成了安卓端的最短路径查询，按照分工，这部分主要由我来完成。

查询功能依然是使用SQL语句的递归来实现的，数据则是靠外部导入数据库，毕竟地铁的信息那么多，不可能靠自己输入。

今天的合作照片

效果展示：

 部分代码：

SearchActivity

package com.example.dataapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.CheckBox;
import android.widget.EditText;

public class SearchActivity extends AppCompatActivity implements View.OnClickListener{

    private Button mBtn_search;
    private EditText eText_start,eText_end;
    private String start,end;
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_search);

        mBtn_search = findViewById(R.id.btn_search);
        mBtn_search.setOnClickListener(this);

        eText_start = findViewById(R.id.et_start);
        eText_end = findViewById(R.id.et_end);

    }

    @Override
    public void onClick(View view) {
        start=eText_start.getText().toString();
        end=eText_end.getText().toString();

        if (view == findViewById(R.id.btn_search)){

            Intent intent = new Intent(this,ShowActivity.class);
            intent.putExtra("start_text",start);
            intent.putExtra("end_text",end);
            startActivity(intent);

        }

    }
}

ShowActivity

package com.example.dataapplication;

import androidx.appcompat.app.AppCompatActivity;

import android.annotation.SuppressLint;
import android.content.Intent;
import android.os.Bundle;
import android.widget.TextView;

import com.example.dataapplication.DataBase.CRUD;
import com.example.dataapplication.Infomation.SubwayBean;

public class ShowActivity extends AppCompatActivity {

    private TextView tv1,tv2,tv3,tv4;
    @SuppressLint("MissingInflatedId")
    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_show);

        tv1=findViewById(R.id.tv_1);
        tv2=findViewById(R.id.tv_2);
        tv3=findViewById(R.id.tv_3);
        tv4=findViewById(R.id.tv_4);

        Intent intent = getIntent();
        String start = intent.getStringExtra("start_text");
        String end = intent.getStringExtra("end_text");
        CRUD crud = new CRUD(this);
        SubwayBean subwayBean = crud.BestTransferStation(start,end);
        tv1.setText(subwayBean._StartStation);
        tv2.setText(subwayBean._EndStation);
        tv3.setText((CharSequence) subwayBean._Number);
        tv4.setText(subwayBean._Path);
    }
}

CRUD

package com.example.dataapplication.DataBase;

import android.annotation.SuppressLint;
import android.content.Context;
import android.database.Cursor;
import android.database.sqlite.SQLiteDatabase;

import com.example.dataapplication.Infomation.SubwayBean;

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

public class CRUD {
    private DBHelper dbHelper;

    public CRUD (Context context){dbHelper = new DBHelper(context);}

    @SuppressLint("Range")
    public SubwayBean BestTransferStation(String station1, String station2){

        SQLiteDatabase db = dbHelper.getReadableDatabase();
        String sql =
                "WITH RECURSIVE transfer(start_station, stop_station, stops, paths) AS (\n" +
                        "SELECT station_name, next_station, 1 stops, \n" +
                        "       line_name||station_name||'->'||line_name||next_station AS paths\n" +
                        "FROM bj_subway\n" +
                        "WHERE station_name = ?\n" +
                        "UNION ALL \n" +
                        "SELECT t.start_station, s.next_station, stops+1, paths||'->'||s.line_name||s.next_station\n" +
                        "FROM transfer t\n" +
                        "JOIN bj_subway s \n" +
                        "ON (t.stop_station = s.station_name AND instr(paths, s.next_station)=0)\n" +
                        ")\n" +
                        "SELECT *\n" +
                        "FROM transfer\n" +
                        "WHERE stop_station = ?;";

        Cursor cursor = db.rawQuery(sql,new String[]{station1,station2});
        SubwayBean subwayBean = new SubwayBean();
        if (cursor.moveToFirst()){
            subwayBean._StartStation = cursor.getString(cursor.getColumnIndex("start_station"));
            subwayBean._EndStation = cursor.getString(cursor.getColumnIndex("stop_station"));
            subwayBean._Number = cursor.getString(cursor.getColumnIndex("stops"));
            subwayBean._Path = cursor.getString(cursor.getColumnIndex("paths"));
        }
        cursor.close();
        db.close();
        return  subwayBean;
    }

}

DBHelper

package com.example.dataapplication.DataBase;

import android.content.Context;
import android.database.sqlite.SQLiteDatabase;
import android.database.sqlite.SQLiteOpenHelper;

public class DBHelper extends SQLiteOpenHelper {
    private static final int DATABASE_VERSION=2;

    private static final String DATABASE_NAME="crud.db";

    public DBHelper(Context context) {
        super(context,DATABASE_NAME,null,DATABASE_VERSION);
    }

    @Override
    public void onCreate(SQLiteDatabase db) {


    }

    @Override
    public void onUpgrade(SQLiteDatabase db, int oldVersion, int newVersion) {


    }
}