生成檔案以在androidstudios中存盤收據-有解無憂

您好，我是 android 作業室的新手。我正在從事航空公司預訂專案。該專案的要求之一是在客戶每次付款時生成一個存盤在外部檔案中的收據。我曾嘗試環顧四周，試圖弄清楚如何在沒有成功的情況下實作這一目標。在應用程式中，我使用 SQLite 作為資料庫，每個用戶在創建帳戶后都會分配到余額。

這是我的 DBHelper 類：

package com.example.shashank.fffffffffffffffffffffffffff;


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

import androidx.annotation.Nullable;

import java.util.ArrayList;
import java.util.List;

public class DBHelper extends SQLiteOpenHelper {
    public static final String DBNAME = "Login.db";
    public static final String FLIGHTS = "FLIGHTS";
    public static final String COLUMN_ID = "ID";
    public static final String COLUMN_DESTINATION = "DESTINATION";
    public static final String COLUMN_PRICE = "PRICE";
    public static final String COLUMN_DEPARTURE_TIME = "DEPARTURE_TIME";
    public static final String COLUMN_ARRIVAL_TIME = "ARRIVAL_TIME";
    public static final String COLUMN_DURATION = "DURATION";
    public static final String COLUMN_AVAILABLE_SEATS = "AVAILABLE_SEATS";
    public static final String USERS = "users";
    public static final String USERNAME = "username";
    public static final String PASSWORD = "password";
    public static final String EMAIL = "email";
    public static final String BALANCE = "balance";
    public static final String BOOKING = "booking";

    public DBHelper(Context context) {
        super(context, "Login.db", null, 1);
    }

    @Override
    public void onCreate(SQLiteDatabase MyDB) {

        String createTable1 = ("create Table "   USERS   "("   USERNAME   " TEXT primary key, "   PASSWORD   " TEXT, "   EMAIL   " TEXT UNIQUE, "   BALANCE   " REAL, "   BOOKING   " INTEGER)");
        MyDB.execSQL(createTable1);

        MyDB.execSQL("CREATE TABLE "   FLIGHTS   "("   COLUMN_ID   " INTEGER PRIMARY KEY AUTOINCREMENT, "   COLUMN_DESTINATION   " TEXT, "   COLUMN_PRICE   " REAL, "   COLUMN_DEPARTURE_TIME   " TEXT, "   COLUMN_ARRIVAL_TIME   " TEXT, "   COLUMN_DURATION   " TEXT, "   COLUMN_AVAILABLE_SEATS   " INTEGER)");


        ContentValues insertValues = new ContentValues();
        insertValues.put(COLUMN_DESTINATION, "Cape Town");
        insertValues.put(COLUMN_PRICE, 2000);
        insertValues.put(COLUMN_DEPARTURE_TIME, "1200");
        insertValues.put(COLUMN_ARRIVAL_TIME, "1400");
        insertValues.put(COLUMN_DURATION, "2");
        insertValues.put(COLUMN_AVAILABLE_SEATS, 10);
        MyDB.insert(FLIGHTS, null, insertValues);

        ContentValues insertValues2 = new ContentValues();
        insertValues2.put(COLUMN_DESTINATION, "Johannesburg");
        insertValues2.put(COLUMN_PRICE, 1000);
        insertValues2.put(COLUMN_DEPARTURE_TIME, "1400");
        insertValues2.put(COLUMN_ARRIVAL_TIME, "1600");
        insertValues2.put(COLUMN_DURATION, "2");
        insertValues2.put(COLUMN_AVAILABLE_SEATS, 22);
        MyDB.insert(FLIGHTS, null, insertValues2);

        ContentValues insertValues3 = new ContentValues();
        insertValues3.put(COLUMN_DESTINATION, "Cape Town");
        insertValues3.put(COLUMN_PRICE, 500);
        insertValues3.put(COLUMN_DEPARTURE_TIME, "1200");
        insertValues3.put(COLUMN_ARRIVAL_TIME, "1400");
        insertValues3.put(COLUMN_DURATION, "2");
        insertValues3.put(COLUMN_AVAILABLE_SEATS, 0);
        MyDB.insert(FLIGHTS, null, insertValues3);

        

    }


    @Override
    public void onUpgrade(SQLiteDatabase MyDB, int i, int i1) {
        MyDB.execSQL("drop Table if exists "   USERS);
        MyDB.execSQL("drop Table if exists "   FLIGHTS);

        onCreate(MyDB);
    }

    public Boolean insertData(String username, String password, String email, Double balance){
        SQLiteDatabase MyDB = this.getWritableDatabase();
        ContentValues contentValues= new ContentValues();
        contentValues.put(USERNAME, username);
        contentValues.put(PASSWORD, password);
        contentValues.put(EMAIL, email);
        contentValues.put(BALANCE, balance);
        long result = MyDB.insert(USERS, null, contentValues);
        if(result==-1) return false;
        else
            return true;
    }

    public Boolean checkusername(String username) {
        SQLiteDatabase MyDB = this.getWritableDatabase();
        Cursor cursor = MyDB.rawQuery("Select * from "   USERS   " where "   USERNAME   " = ?", new String[]{username});
        if (cursor.getCount() > 0)
            return true;
        else
            return false;
    }

    public Boolean checkusernamepassword(String username, String password){
        SQLiteDatabase MyDB = this.getWritableDatabase();
        Cursor cursor = MyDB.rawQuery("Select * from "   USERS   " where "   USERNAME   " = ? and "   PASSWORD   " = ?", new String[] {username,password});
        if(cursor.getCount()>0)
            return true;
        else
            return false;
    }


    public List<FlightsModel> getEveryone(){

        List<FlightsModel> returnList = new ArrayList<>();

        String queryString = "SELECT * FROM "   FLIGHTS;

        SQLiteDatabase db = this.getReadableDatabase();

        Cursor cursor = db.rawQuery(queryString, null);

        if(cursor.moveToFirst()){
            do {
                int id = cursor.getInt(0);
                String destination = cursor.getString(1);
                double price = cursor.getDouble(2);
                String departure = cursor.getString(3);
                String arrival = cursor.getString(4);
                String duration = cursor.getString(5);
                int space = cursor.getInt(6);

                FlightsModel newFlight = new FlightsModel(id, destination, price, departure, arrival, duration, space);
                returnList.add(newFlight);


            }while (cursor.moveToNext());
        }
        else{

        }
        cursor.close();
        db.close();
        return returnList;
    }



    @SuppressLint("Range") // suppress Bug/issue with getColumnIndex
    public FlightsModel getFlightById(int id) {
        FlightsModel rv;
        SQLiteDatabase db = this.getWritableDatabase();
        // Uses the query convenience method rather than raw query
        Cursor csr = db.query(FLIGHTS,null,COLUMN_ID "=?",new String[]{String.valueOf(id)},null,null,null);
        if (csr.moveToFirst()) {
            rv = new FlightsModel(
                    csr.getInt(csr.getColumnIndex(COLUMN_ID)),
                    csr.getString(csr.getColumnIndex(COLUMN_DESTINATION)),
                    csr.getDouble(csr.getColumnIndex(COLUMN_PRICE)),
                    csr.getString(csr.getColumnIndex(COLUMN_DEPARTURE_TIME)),
                    csr.getString(csr.getColumnIndex(COLUMN_ARRIVAL_TIME)),
                    csr.getString(csr.getColumnIndex(COLUMN_DURATION)),
                    csr.getInt(csr.getColumnIndex(COLUMN_AVAILABLE_SEATS))
            );
        }  else {
            rv = new FlightsModel();
        }
        csr.close();
        // No need to close the database (inefficient to keep opening and closing db)
        return rv;
    }



    @SuppressLint("Range")
    public UsersModel getPasswordByName(String name){

        UsersModel rv;
        SQLiteDatabase db = this.getWritableDatabase();

        Cursor cr = db.query(USERS, null, USERNAME "=?", new String[]{name}, null, null, null);

        if (cr.moveToFirst()) {
            rv = new UsersModel(
                    cr.getString(cr.getColumnIndex(USERNAME)),
                    cr.getString(cr.getColumnIndex(PASSWORD)),
                    cr.getString(cr.getColumnIndex(EMAIL)),
                    cr.getDouble(cr.getColumnIndex(BALANCE)),
                    cr.getInt(cr.getColumnIndex(BOOKING))

            );
        }  else rv = new UsersModel();

        cr.close();
        return rv;
    }

    public int setBookingByUserName(int bookingAmount, String userName) {
        ContentValues cv = new ContentValues();
        cv.put(BOOKING,bookingAmount);
        return this.getWritableDatabase().update(USERS,cv,USERNAME "=?",new String[]{userName});
    }

    public double makingPayment(double balance, String userName){
        ContentValues cv = new ContentValues();
        cv.put(BALANCE,balance);
        return this.getWritableDatabase().update(USERS,cv,USERNAME "=?",new String[]{userName});
    }


    public int setAvailableSeatsAfterPayment(int seats, int flightID){
        ContentValues cv = new ContentValues();
        cv.put(COLUMN_AVAILABLE_SEATS,seats);
        return this.getWritableDatabase().update(FLIGHTS,cv,COLUMN_ID "=?",new String[]{String.valueOf(flightID)});
    }


    public int cancelBooking(int bookingAmount, String userName){
        ContentValues cv = new ContentValues();
        cv.put(BOOKING,bookingAmount);
        return this.getWritableDatabase().update(USERS,cv,USERNAME "=?",new String[]{String.valueOf(userName)});
    }


}

當客戶預訂航班時，使付款方法用于使用新余額更新資料庫。

這是預訂活動：

package com.example.shashank.fffffffffffffffffffffffffff;

import androidx.appcompat.app.AppCompatActivity;

import android.content.Intent;
import android.os.Bundle;
import android.view.View;
import android.widget.Button;
import android.widget.TextView;
import android.widget.Toast;

public class BookingActivity extends AppCompatActivity {


    TextView textView;
    TextView departure, arrival, duration, price, seats;

    DBHelper dbHelper; //<<<<< ADDED
    Button book, accountBtn;
    FlightsModel flightsModel; //<<<<< ADDED
    UsersModel userModel;


    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_booking);

        dbHelper = new DBHelper(this); //<<<<< ADDED

        textView = findViewById(R.id.textView);
        departure = findViewById(R.id.departure);
        arrival = findViewById(R.id.arrival);
        duration = findViewById(R.id.duration);
        price = findViewById(R.id.price);
        seats = findViewById(R.id.seats);
        book = findViewById(R.id.button2);
        accountBtn = findViewById(R.id.accountBtn);


        Intent mIntent = getIntent();
        int intValue = mIntent.getIntExtra("intVariableName", 0);
        Intent nameIntent = getIntent();
        String name = nameIntent.getStringExtra("userName");
        flightsModel = dbHelper.getFlightById(intValue   1);


        intValue = intValue   1;
        textView.setText(flightsModel.getDestination());
        departure.setText(flightsModel.getDeparture_time());
        arrival.setText(flightsModel.getArrival_time());
        duration.setText(flightsModel.getDuration());
        price.setText("R"    Double.toString(flightsModel.getPrice()));
        seats.setText(Integer.toString(flightsModel.getAvailable_space()));







        book.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                int intValue, seats;
                Intent mIntent = getIntent();
                intValue = mIntent.getIntExtra("intVariableName", 0);
                intValue = intValue   1;

                dbHelper = new DBHelper(BookingActivity.this);
                flightsModel = dbHelper.getFlightById(intValue);
                double price;
                price = flightsModel.getPrice();

                userModel = dbHelper.getPasswordByName(name);
                double balance;
                balance = userModel.getBalance();

                String name = nameIntent.getStringExtra("userName");

                seats = flightsModel.getAvailable_space();



                if(seats == 0){
                    Toast.makeText(BookingActivity.this, "Booking unsuccessful, no available seats", Toast.LENGTH_SHORT).show();
                }else{
                    if(price <= balance){
                        dbHelper.setBookingByUserName(intValue, name);
                        Toast.makeText(BookingActivity.this, "Payment successful, booking has been made", Toast.LENGTH_SHORT).show();
                        double newBalance;
                        newBalance = balance - price;
                        dbHelper.makingPayment(newBalance, name);
                        seats = seats - 1;
                        dbHelper.setAvailableSeatsAfterPayment(seats, intValue);
                    }else{
                        Toast.makeText(BookingActivity.this, "Payment unsuccessful, not enough funds", Toast.LENGTH_SHORT).show();
                    }
                }





            }
        });


        accountBtn.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {
                Intent intent = new Intent(BookingActivity.this, AccountActivity.class);
                intent.putExtra("userName", name);
                startActivity(intent);
            }
        });




    }


}

因此，一旦客戶進行預訂，就需要生成收據檔案，例如航班詳情、時間、日期和航班價格。任何幫助將不勝感激，謝謝。

uj5u.com熱心網友回復：

下面是一個例子，在收據子目錄下的 App 的 Files 目錄中保存一個檔案。檔案名由值組成，例如 Fred-Cape Town-1200-1400

存盤在/data/user/0/the_package_name/files/receipts/Fred-Cape Town-1200-1400

檔案本身，在示例中包含：-

Fred
Cape Town
1200
1400

添加到 DBHelper 的一些支持方法：-

public UsersModel getUsersModelByName(String userName) {
    UsersModel rv = new UsersModel();
    SQLiteDatabase db = this.getWritableDatabase();
    Cursor csr = db.query(USERS,null,USERNAME "=?", new String[]{userName},null,null,null);
    if (csr.moveToFirst()) {
        rv = new UsersModel(
                csr.getString(csr.getColumnIndex(USERNAME)),
                csr.getString(csr.getColumnIndex(PASSWORD)),
                csr.getString(csr.getColumnIndex(EMAIL)),
                csr.getDouble(csr.getColumnIndex(BALANCE)),
                csr.getInt(csr.getColumnIndex(BOOKING))
        );
    }
    csr.close();
    return rv;
}

public boolean makeBooking(String userName, int bookingId) {
    SQLiteDatabase db = this.getWritableDatabase();
    ContentValues cv = new ContentValues();
    cv.put(BOOKING,bookingId);
    return db.update(USERS,cv,USERNAME   "=?", new String[]{userName}) > 0;
}

現在makeBookReceiptFile方法，也放在 DBHelper 類中：-

public String makeBookReceiptFile(String userName, Context context) {
    String rcpts_directory = "receipts";
    String rv = "";
    SQLiteDatabase db = this.getWritableDatabase();
    UsersModel currentUser = getUsersModelByName(userName);
    FlightsModel currentFlightsModel = new FlightsModel();
    if (currentUser.booking > 0) {
        currentFlightsModel = getFlightById(currentUser.booking);
        if (currentFlightsModel.id < 1) {
            rv = "INVALID - unable to extract booking for id "   currentUser.booking;
        }
    } else {
        rv = "INVALID - unable to extract user who's name is "   userName;
    }
    if (rv.length() > 0) return rv;
    String rcpt_filename =
            currentUser.username   "-"  
                    currentFlightsModel.destination   "-"  
                    currentFlightsModel.departure   "-"  
                    currentFlightsModel.arrival
            ;
    File rcpt = new File(context.getFilesDir().getPath()   File.separatorChar   rcpts_directory   File.separatorChar   rcpt_filename);
    rcpt.getParentFile().mkdirs();
    try {
        FileWriter fw = new FileWriter(rcpt);
        fw.write(userName  
                "\n"   currentFlightsModel.destination 
                "\n"   currentFlightsModel.departure  
                "\n"   currentFlightsModel.arrival
        );
        fw.flush();
        fw.close();
        rv = rcpt.getAbsolutePath();
    } catch (IOException e) {
        e.printStackTrace();
        rv = "IOERROR - "   e.getMessage();
    }
    return rv;
}

首先它根據用戶名檢索用戶模型，然后根據預訂 ID 檢索航班模型。

如果沒有獲得，則回傳一個以 INVALID 開頭的字串

然后它通過背景關系獲取 Files 目錄。生成檔案的路徑。制作任何丟失的目錄。將資料寫入檔案，重繪并關閉回傳路徑的檔案，或者如果出現 io 錯誤則顯示錯誤訊息。

以上測驗使用： -

    db = new DBHelper(this);

    db.insertData("Fred","password","fed@email",0.00);
    UsersModel fred = db.getUsersModelByName("Fred");
    db.makeBooking(fred.username,1);
    Log.d("RESULTINFO",db.makeBookReceiptFile("Fred",this));

結果（通過設備資源管理器）：-

生成檔案以在 android studios 中存盤收據

如果您對檔案的位置有疑問，則必須閱讀https://developer.android.com/training/data-storage/

轉載請註明出處，本文鏈接：https://www.uj5u.com/qiye/370834.html

標籤：爪哇安卓 sqlite

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