Adapter Design Pattern

电压实体类

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 7:55
 */
public class Volt {

    private int volts;

    public Volt(int v) {
        this.volts = v;
    }

    public int getVolts() {
        return volts;
    }

    public void setVolts(int volts) {
        this.volts = volts;
    }

}

默认是120V的插板

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 7:56
 */
public class Socket {

    public Volt getVolt(){
        return new Volt(120);
    }
}

插板适配类

包含默认的120V，新增了12V和3V

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 7:56
 */
public interface SocketAdapter {

    Volt get120Volt();

    Volt get12Volt();

    Volt get3Volt();

}

通过继承Socket，引入默认的Socket，同时实现SocketAdapter 新增3V 和 12V

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 7:58
 */
public class SocketClassAdapterImpl extends Socket implements SocketAdapter {

    @Override
    public Volt get120Volt() {
        return getVolt();
    }

    @Override
    public Volt get12Volt() {
        Volt v = getVolt();
        return convertVolt(v, 10);
    }

    @Override
    public Volt get3Volt() {
        Volt v = getVolt();
        return convertVolt(v, 40);
    }

    private Volt convertVolt(Volt v, int i) {
        return new Volt(v.getVolts() / i);
    }


}

通过组合引入Socket,同时实现SocketAdapter 新增3V 和 12V

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 8:00
 */
public class SocketObjectAdapterImpl implements SocketAdapter {

    //Using Composition for adapter pattern
    private Socket sock = new Socket();

    @Override
    public Volt get120Volt() {
        return sock.getVolt();
    }

    @Override
    public Volt get12Volt() {
        Volt v = sock.getVolt();
        return convertVolt(v, 10);
    }

    @Override
    public Volt get3Volt() {
        Volt v = sock.getVolt();
        return convertVolt(v, 40);
    }

    private Volt convertVolt(Volt v, int i) {
        return new Volt(v.getVolts() / i);
    }

}

测试

package com.sheting.design.pattern.demo4;

/**
 * @Author SheTing
 * @Time 2018/3/22 7:59
 */
public class AdapterPatternTest {

    public static void main(String[] args) {

        testClassAdapter();
        testObjectAdapter();
    }

    private static void testObjectAdapter() {
        SocketAdapter sockAdapter = new SocketObjectAdapterImpl();
        Volt v3 = getVolt(sockAdapter, 3);
        Volt v12 = getVolt(sockAdapter, 12);
        Volt v120 = getVolt(sockAdapter, 120);
        System.out.println("v3 volts using Object Adapter=" + v3.getVolts());
        System.out.println("v12 volts using Object Adapter=" + v12.getVolts());
        System.out.println("v120 volts using Object Adapter=" + v120.getVolts());
    }

    private static void testClassAdapter() {
        SocketAdapter sockAdapter = new SocketClassAdapterImpl();
        Volt v3 = getVolt(sockAdapter, 3);
        Volt v12 = getVolt(sockAdapter, 12);
        Volt v120 = getVolt(sockAdapter, 120);
        System.out.println("v3 volts using Class Adapter=" + v3.getVolts());
        System.out.println("v12 volts using Class Adapter=" + v12.getVolts());
        System.out.println("v120 volts using Class Adapter=" + v120.getVolts());
    }

    private static Volt getVolt(SocketAdapter sockAdapter, int i) {
        switch (i) {
            case 3:
                return sockAdapter.get3Volt();
            case 12:
                return sockAdapter.get12Volt();
            case 120:
                return sockAdapter.get120Volt();
            default:
                return sockAdapter.get120Volt();
        }
    }

}

Adapter Design Pattern Example in JDK

• java.util.Arrays#asList()
• java.io.InputStreamReader(InputStream) (returns a Reader)
• java.io.OutputStreamWriter(OutputStream) (returns a Writer)
• java.awt.event.MouseAdapter