JAVA設計模式-Adapter

有些時候，我們想要使用一些類的某個功能，但是發現這個類提供的接口不符合我們的要求，這個時候就需要讓這個接口符合要求，最直接想到的辦法就是去改這個接口，但是這個辦法明顯違背了面向對象的原則。所以，爲了解決這個辦法，就提出了Adapter模式。Adapter模式分爲兩種，一種是類Adapter，一種是對象Adapter，後面將對這兩種方法進行詳細的解釋。

 

    首先是類Adapter。

 

   

interface Operation{
    public int add(int a,int b);
}
class Calculater{
    public int otherAdd(int a,int b){
        return a + b;
    }
}
class OperationAdapter extends Calculater implements Operation{
    @Override
    public int add(int a, int b) {
        // TODO Auto-generated method stub
        return otherAdd(a,b);
    }
}
public class Test{
    public static void main(String[] args){
        OperationAdapter adapter = new OperationAdapter();
        int x = 10;
        int y = 20;
        int sum = adapter.add(x, y);
        System.out.println(x + " + " + y + " = " + sum);
    }
}

interface Operation{ public int add(int a,int b); } class Calculater{ public int otherAdd(int a,int b){ return a + b; } } class OperationAdapter extends Calculater implements Operation{ @Override public int add(int a, int b) { // TODO Auto-generated method stub return otherAdd(a,b); } } public class Test{ public static void main(String[] args){ OperationAdapter adapter = new OperationAdapter(); int x = 10; int y = 20; int sum = adapter.add(x, y); System.out.println(x + " + " + y + " = " + sum); } }

 

    上面的代碼中，OperationAdapter這個類將Calculater的add()方法適配到Operation這個類裏面，OperationAdapter就是一個適配器。這樣做有一個問題，當適配器需要從多個類裏面調用方法的時候，類Adapter方法就不適用了，因爲java不允許多重繼承，既然不能用繼承，那麼就用組合好了，因此，就有了對象Adapter。

 

   

package adapter.objectAdapter;

interface Operation{
    public int add(int a,int b);
    public int minus(int a,int b);
    public int multiplied(int a,int b);
}
class OtherAdd{
    public int otherAdd(int a,int b){
        return a + b;
    }
}

class OtherMinus{
    public int minus(int a,int b){
        return a - b;
    }
}

class OtherMultiplied{
    public int multiplied(int a,int b){
        return a * b;
    }
}
class OperationAdapter implements Operation{
    private OtherAdd add;
    private OtherMinus minus;
    private OtherMultiplied multiplied;

    public OperationAdapter(){
        add = new OtherAdd();
        minus = new OtherMinus();
        multiplied = new OtherMultiplied();
    }

    @Override
    public int add(int a, int b) {
        // TODO Auto-generated method stub
        return add.otherAdd(a,b);
    }

    @Override
    public int minus(int a, int b) {
        // TODO Auto-generated method stub
        return minus.minus(a,b);
    }

    @Override
    public int multiplied(int a, int b) {
        // TODO Auto-generated method stub
        return multiplied.multiplied(a,b);
    }
}
public class Test{
    public static void main(String[] args){
        OperationAdapter adapter = new OperationAdapter();
        int x = 10;
        int y = 20;
        System.out.println(x + " + " + y + " = " + adapter.add(x, y));
        System.out.println(x + " - " + y + " = " + adapter.minus(x, y));
        System.out.println(x + " * " + y + " = " + adapter.multiplied(x, y));
    }
}

package adapter.objectAdapter; interface Operation{ public int add(int a,int b); public int minus(int a,int b); public int multiplied(int a,int b); } class OtherAdd{ public int otherAdd(int a,int b){ return a + b; } } class OtherMinus{ public int minus(int a,int b){ return a - b; } } class OtherMultiplied{ public int multiplied(int a,int b){ return a * b; } } class OperationAdapter implements Operation{ private OtherAdd add; private OtherMinus minus; private OtherMultiplied multiplied; public OperationAdapter(){ add = new OtherAdd(); minus = new OtherMinus(); multiplied = new OtherMultiplied(); } @Override public int add(int a, int b) { // TODO Auto-generated method stub return add.otherAdd(a,b); } @Override public int minus(int a, int b) { // TODO Auto-generated method stub return minus.minus(a,b); } @Override public int multiplied(int a, int b) { // TODO Auto-generated method stub return multiplied.multiplied(a,b); } } public class Test{ public static void main(String[] args){ OperationAdapter adapter = new OperationAdapter(); int x = 10; int y = 20; System.out.println(x + " + " + y + " = " + adapter.add(x, y)); System.out.println(x + " - " + y + " = " + adapter.minus(x, y)); System.out.println(x + " * " + y + " = " + adapter.multiplied(x, y)); } }

 

    總的來說，對象Adapter比起類Adapter來說要更有用一些，代碼很簡單，不解釋，你們懂的。