carstore.java

一个非常好的赛车游戏代码

import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
import javax.microedition.io.*;
import javax.microedition.rms.*;
import java.io.*;


public class CarStore
{
    // These two static final ints will
    // be used to filter the records via
    // a RecordFilter implementation.
    public static final int CASH_RECORD = 1;
    public static final int WEAPON_RECORD = 2;

    // The player's current weapons
    private Weapon[] weapons;

    // The player's current cash
    private int cash = 0;

    // Build a new CarStore and set the
    // members
    CarStore() 
    {
    }

    // Writes the cash and weapon data to a new
    // RecordStore.
    public void writeToStore()
    {
        try
        {
            // Let's make sure we're dealing with a fresh new RecordStore
            // (since we're still relying a little on recordId ordering)
            // and remove it if it's still in device storage.
            RecordStore.deleteRecordStore("Car");
        } 
        catch (RecordStoreException rse)
        {
            // This probably means we haven't created a store yet.
		System.err.println(rse);
        }

        RecordStore carDB = null;

        // Now we're ready
        try
        {

            // Now we'll create a new one.
            carDB = RecordStore.openRecordStore( "Car", true );

            // Build some reusable data handling objects.
            ByteArrayOutputStream bout = new ByteArrayOutputStream();
            DataOutputStream dout = new DataOutputStream(bout);
            byte[] data = null;

            // First, we're going to write the player's
            // current cash to the car's RecordStore
            // We'll id the record as a cash record...
            dout.writeByte(CASH_RECORD);

            // and then write the cash amount
            dout.writeInt(cash);

            // and now bundle the Stream into a byte
            // array and write a new record.  It's
            // the very first record in the RecordStore,
            // so we know it'll have the recordId of 1.
            data = bout.toByteArray();

            // Add the array to the RecordStore
            carDB.addRecord(data, 0, data.length );

            // and reset the Streams to
            // properly handle the Weapons.
            bout.reset();

            // Iterate through the car's Weapons array
            for (int i = 0; i < weapons.length; i++)
            {
                // Write the weapon record tag..
                dout.writeByte(WEAPON_RECORD);

                // Write the weapon type...
                dout.writeInt(weapons[i].getWeaponType());

                // Write the weapon's ammo
                dout.writeInt(weapons[i].getWeaponAmmo());

                // Write the Weapon's time value
                dout.writeInt(weapons[i].getWeaponTime());
                
                // Write the weapon's name
                dout.writeUTF(weapons[i].getName());
                
                // Write the weapon's description
                dout.writeUTF(weapons[i].getDescription());

                dout.flush();

                // Pack the Byte Stream (aka the Data Stream)
                // into the data byte array...
                data = bout.toByteArray();

                // Add the array to the RecordStore
                carDB.addRecord(data, 0, data.length );

                // and reset the Streams to
                // properly handle the next Weapon.
                bout.reset();
            }
            carDB.closeRecordStore();
            dout.close();
            bout.close();

        }
        catch (Exception e)
        {
		try { carDB.closeRecordStore(); } catch (Exception e2) { }
            e.printStackTrace();
        }
    }

    public boolean readStore()
    {
        RecordStore carDB = null;
        try
        {
            // Open the RecordStore built above...
            carDB = RecordStore.openRecordStore( "Car", false );

            // Build some reusable data handling objects.
            ByteArrayInputStream bin = null;
            DataInputStream din = null;
            byte[] data = null;

            // First, we'll get the cash record out and set
            // the cash value.  Remember that this record
            // was added before any other so we know it's
            // at recordId == 1.
            data = carDB.getRecord(1);

            // Set up the streams to read back the
            // stored variables
            bin = new ByteArrayInputStream(data);
            din = new DataInputStream(bin);

            // discard the CASH_RECORD byte
            din.readByte();

            // and now grab the actual cash value stored.
            cash = din.readInt();
            System.out.println("Cash: "+cash);

            // clean up for the weapons handling
            din.close();
            bin.close();

            // Prepare the Weapons array for the new data
            // (We build it to (getNumRecords()-1) to account
            // for the cash record.)
            weapons = new Weapon[carDB.getNumRecords()-1];
            // The following sets up a RecordEnumeration
            // object with our CarItemFilter RecordFilter
            // and a null RecordComparator which means
            // it will simply iterate the weapon records
            // in no particular order.  We're assuming, here,
            // that the Weapon records found won't need to be
            // in a certain sequence but can be rebuilt
            // willy-nilly.  You can always build your
            // own RecordComparator to put the enumeration into
            // some specific order.
            CarItemFilter filter = new CarItemFilter(WEAPON_RECORD);
            RecordEnumeration re = carDB.enumerateRecords(filter, null, false);

            // Prepare the necessary temp variables and
            int count = 0;
            int type = 0;
            int time = 0;
            int ammo = 0;
            String name = "";
            String description = "";
            while (re.hasNextElement())
            {
                // This next call returns the record's byte array and
                // advances the RecordEnumerator's pointer to the record
                // beyond the one returned.
                data = re.nextRecord();

                // Set up the streams...
                bin = new ByteArrayInputStream(data);
                din = new DataInputStream(bin);

                // Read and discard the weapon record id
                din.readByte();

                // Read the weapon type...
                type = din.readInt();

                // Read the weapon's ammo
                ammo = din.readInt();

                // Read the Weapon's time value
                time = din.readInt();
                
                // Read the Weapon's name 
                name = din.readUTF();
                System.out.println(count+") Got the Weapon name: "+name);

                // Read the Weapon's description
                description = din.readUTF();
                
                // Now rebuild the weapon into the
                // weapons array.
                weapons[count++] = new Weapon(type, time, ammo,name,description);

                // Clean up
                din.close();
                bin.close();
            }
        }
        catch (Exception e)
        {
            System.err.println("Exception in readStore()"+e);
		// This probably means we haven't created a store yet.
            try { carDB.closeRecordStore(); } catch (Exception e2) { }
            return false;
        }

        try { carDB.closeRecordStore(); } catch (Exception e2) { }
        System.out.println("Done Reading From Store");
        return true;
    }

    public int getCash() 
    {
        return cash;
    }

    public void setCash(int amount) 
    {
        cash = amount;
    }
    
    public Weapon[] getWeapons() 
    {
        return weapons;
    }

    public void setWeapons(Weapon[] w) 
    {
        weapons = w;
    }

}

// This class is the RecordFilter we'll use to
// find all the Weapon records.
class CarItemFilter implements RecordFilter
{
    // This will contain the car item id
    // we'll be looking for in the records.
    private byte filterValue;

    // Builds a new CarItemFilter for the
    // specific car record id we want to
    // find
    public CarItemFilter(int filterInt)
    {
        filterValue = (byte)filterInt;
    }

    // This is the RecordFilter method used
    // by the RecordEnumeration to determine
    // if the record is a "match" and needs
    // to be included in its enumeration.
    public boolean matches(byte[] candidate)
    {
        if (candidate == null || candidate.length == 0)
        {
            return false;
        }
        // Since, in the CarStore.writeToStore() method,
        // we wrote the item type byte to the records
        // before anything else, the byte at index 0
        // should be our id to filter.
        return (candidate[0] == filterValue);

    }

}