Java解决方案中的动态类创建

Question

I know that this will not work, which sucks IMO, but I am wondering what is my best solution. After some searching I have found out about ORM and hibernate. After finding out about them I have found many people who say its more hassle than it is worth and promotes laziness. Please can anyone point me in a good direction?

//Setup the weapon classes
logger.info("Initializing the weapon classes.");
stat = conn.prepareStatement("SELECT *" + 
                            " FROM " + DB_NAME + ".weapons");
rs = stat.executeQuery();
while (rs.next()) {
    Weapon rs.getString("name") = new Weapon(rs.getint("weapon_id"), rs.getString("name"), rs.getString("description"), rs.getString("filename"), rs.getint("rarity"), rs.getint("sell_price"), rs.getint("quantity_max"), rs.getint("slot"), rs.getint("level_requirement"), rs.getint("strength_requirement"), rs.getint("dexterity_requirement"), rs.getint("intelligence_requirement"), rs.getint("enchanted_increase"), rs.getint("enchanted_cost"), rs.getint("hit_min"), rs.getint("hit_max"), rs.getint("speed"), rs.getint("elemental_type"), rs.getint("elemental_hit_min"), rs.getint("elemental_hit_max"));
}

I know this has been asked many times, but I am just finding so many contradictory opinions. :(

Answer 1

I would suggest using a Map to store your instance for weapons that you fetch from your database. The key would be the name and the value would be an instance of your Weapons class.

Something like:

while(rs.next()){
    Weapon weapon = new Weapon(rs.getint("weapon_id"), rs.getString("name"), rs.getString("description"), rs.getString("filename"), rs.getint("rarity"), rs.getint("sell_price"), rs.getint("quantity_max"), rs.getint("slot"), rs.getint("level_requirement"), rs.getint("strength_requirement"), rs.getint("dexterity_requirement"), rs.getint("intelligence_requirement"), rs.getint("enchanted_increase"), rs.getint("enchanted_cost"), rs.getint("hit_min"), rs.getint("hit_max"), rs.getint("speed"), rs.getint("elemental_type"), rs.getint("elemental_hit_min"), rs.getint("elemental_hit_max"));
    //Assuming you have an instance of Map<String, Weapon>
    map.add(rs.getString("name"), weapon);
}

Answer 2

Using an ORM depends on your project size. Personally, and by looking at your understanding of Java, I would not recommend that you jump into hibernate and such for now. I would suggest that you play directly with SQL first so you have a better understanding of persistence.

As for the code you posted, here is what you could do :

//Setup the weapon classes
logger.info("Initializing the weapon classes.");
stat = conn.prepareStatement("SELECT *" + 
                            " FROM " + DB_NAME + ".weapons");

HashMap<String, Weapon> weapons = new HashMap<String, Weapon>();

rs = stat.executeQuery();
while (rs.next()) {
    Weapon weapon = new Weapon()
        .setId(rs.getint("weapon_id"))
        .setName(rs.getString("name"))
        .setDescription(rs.getString("description"))
        .setFilename(rs.getString("filename"))
        .setRarity(rs.getint("rarity"))
        .setSellPrice(rs.getint("sell_price"))
        .setQuantityMax(rs.getint("quantity_max"))
        .setSlot(rs.getint("slot"))
        .setLvlRequirement(rs.getint("level_requirement"))
        .setStrRequirement(rs.getint("strength_requirement"))
        .setDexRequirement(rs.getint("dexterity_requirement"))
        .setIntRequirement(rs.getint("intelligence_requirement"))
        .setEnchantedInc(rs.getint("enchanted_increase"))
        .setEnchantedCost(rs.getint("enchanted_cost"))
        .setHitMin(rs.getint("hit_min"))
        .setHitMax(rs.getint("hit_max"))
        .setSpeed(rs.getint("speed"))
        .setElementalType(rs.getint("elemental_type"))
        .setElementalHitMin(rs.getint("elemental_hit_min"))
        .setElementalHitMax(rs.getint("elemental_hit_max"));

    weapons.put(rs.getString("name"), weapon);
}

Avoid having a constructor (or even a method!) with so many arguments. Unless you are exporting your class to a third party or exposing it to some user plugins and don't want anyone to change the internal values, don't worry about setters! Then each set* methods return this so they can be chained. For example :

public Weapon setHitMax(int max) {
    this.hitMax = max;
    return this;
}

And you can, then access your weapons using the Map . Like, for example :

weapons.get("sword").getHitMax();

Answer 3

What exactly do you mean by "dynamic class creation"? There's two things I can understand from your code:

a) you're a reaallly bad Java programmer :) or

b) you're trying to have your variable named differently for each row in the database, (which doesn't make any sense)