Java模式原型在游戏服务器架构中的应用与优化

// Java Program to Create Abstract Enemy class 
// Abstrat class
public abstract class Enemy {
  // enemy health
   public int health; 
   // enemy speed
   public int speed; 
   // enemy name
   public String name; 
   // Constructor 1
   // Base constructor 
   public Enemy() { 
   }
   // Constructor 2 
   // Copy constructor 
   public Enemy(Enemy target) {  
      // Check that target not empty
       if (target != null) {           
          // set base params and note 
           // this keyword refers to current instance itself
           this.health = target.health;
           this.speed = target.speed;
           this.name = target.name;
       }
   }
   // clone() method 
   public abstract Enemy clone(); 
   // Override equals() method 
   @Override
   public boolean equals(Object o) { 
       if (!(o instanceof Enemy)) return false;
       Enemy enemy = (Enemy) o;
       return enemy.health == health && enemy.speed == speed && Objects.equals(enemy.name, name);
   }
  // Override hashCode() method 
   @Override
   public int hashCode() {
       return Objects.hash(health, speed, name);
   }
}


// Let`s create ArcherEnemy with attack range
public class ArcherEnemy extends Enemy { // Enemy is a parent
   public int attackRange; // add new param
   public ArcherEnemy() {
   }
   public ArcherEnemy(ArcherEnemy target) { // clone constructor
       super(target); // first of all clone base Enemy
       if (target != null) {
           this.attackRange = target.attackRange; // then clone additional params
       }
   }
   /*
    Clone based on THIS enemy
   */
   @Override
   public Enemy clone() {
       return new ArcherEnemy(this);
   }
   @Override
   public boolean equals(Object o) {
       if (this == o) return true;
       if (o == null || getClass() != o.getClass()) return false;
       if (!super.equals(o)) return false;
       ArcherEnemy that = (ArcherEnemy) o;
       return attackRange == that.attackRange ;
   }
   @Override
   public int hashCode() {
       return Objects.hash(super.hashCode(), attackRange);
   }
}


// Let`s create MeleeEnemy with 'melee params'
public class MeleeEnemy extends Enemy {
    public int blockChance; // add new param
    public boolean withShield; // add new param
    public MeleeEnemy() {}
    // Create clone constructor
    // clone base Enemy
    // and then clone additional params
    public MeleeEnemy(MeleeEnemy target)
    {
        super(target);
        if (target != null) {
            this.blockChance = target.blockChance;
            this.withShield = target.withShield;
        }
    }
    //  Clone class based on current values
    @Override public Enemy clone()
    {
        return new MeleeEnemy(this);
    }
    @Override public boolean equals(Object o)
    {
        if (this == o)
            return true;
        if (o == null || getClass() != o.getClass())
            return false;
        if (!super.equals(o))
            return false;
        MeleeEnemy that = (MeleeEnemy)o;
        return blockChance == that.blockChance
            && withShield == that.withShield;
    }
    @Override public int hashCode()
    {
        return Objects.hash(super.hashCode(), blockChance,
                            withShield);
    }
}


// Java Program to Illustarey Creation of Clones
// Main class
public class Demo {
    // Method 2
    // Main driver method
    public static void main(String[] args)
    {
        // Creating enemy list
        List<Enemy> enemyList = new ArrayList<>();
        // Creating enemy list copy
        List<Enemy> enemyListCopy = new ArrayList<>();
        // Create baseArcher
        ArcherEnemy baseArcher = new ArcherEnemy();
        // Setting attributes
        baseArcher.health = 150;
        baseArcher.speed = 35;
        baseArcher.name = "Base Archer";
        baseArcher.attackRange = 100;
        enemyList.add(baseArcher);
        // Create clone baseArcher
        ArcherEnemy baseArcherClone
            = (ArcherEnemy)baseArcher.clone();
        // Adding clone to enemyList
        enemyList.add(baseArcherClone);
        // Create baseMeleeEnemy
        MeleeEnemy baseMeleeEnemy = new MeleeEnemy();
        // Setting attributes
        baseMeleeEnemy.health = 10;
        baseMeleeEnemy.speed = 20;
        baseMeleeEnemy.name = "blue";
        baseMeleeEnemy.blockChance = 7;
        baseMeleeEnemy.withShield = true;
        // Now adding baseMeleeEnemy to enemyList
        // using add() method
        enemyList.add(baseMeleeEnemy);
        // Cloning whole list and comparing
        cloneAndCompare(enemyList, enemyListCopy);
    }
    // Method 1
    // To clone and compare
    private static void
    cloneAndCompare(List<Enemy> enemyList,
                    List<Enemy> enemyListCopy)
    {
        // Iterate over enemyList
        // using for-each loop
        for (Enemy enemy : enemyList) {
            // Clone enemyes and add into enemyListCopy
            enemyListCopy.add(enemy.clone());
        }
        // Compare enemyes in enemyList and in enemyListCopy
        for (int i = 0; i < enemyList.size(); i++) {
            // Checking that enemy and cloneEnemy have
            // different links
            if (enemyList.get(i) != enemyListCopy.get(i)) {
                // Simply printing the result
                System.out.println(
                    i
                    + ": Enemy are different objects (yay!)");
                // Check that they have same params
                if (enemyList.get(i).equals(
                        enemyListCopy.get(i))) {
                    // Print statement if they are identical
                    System.out.println(
                        i
                        + ": And they are identical (yay!)");
                }
                else { // Print statement if they are
                       // not-identical
                    System.out.println(
                        i
                        + ": But they are not identical (booo!)");
                }
            }
            else {
                // Print statement if Shape objects are same
                System.out.println(
                    i
                    + ": Shape objects are the same (booo!)");
            }
        }
    }
}


0: Enemy are different objects (yay!) // have different links
0: And they are identical (yay!) // but have same inner state
1: Enemy are different objects (yay!) // have different links
1: And they are identical (yay!) // but have same inner state
2: Enemy are different objects (yay!) // have different links
2: And they are identical (yay!) // but have same inner state