Structural Patterns Part 2/7: Bridge Pattern

Structural Patterns Part 2/7: Bridge Pattern

目录

Structural Patterns Part 27 Bridge Pattern

目录

Definition

UML Class Diagram

Implementation

Definition

Bridge Pattern是分离抽象和接口的模式，这样抽象的实现类就不用与接口紧密的耦合在一起了。

一句话：

Decouple an abstraction from its implementation so that the two can vary independently.

何时使用?当希望分离抽象类的接口和抽象类的具体实现类时。

使用频率：

Medium

UML Class Diagram

Implementation

Phone类想要实现HeadSet接口从而达到可以听歌的效果。

这里就可以看出，抽象类Phone的具体实现类MOTO已经完全与HeadSet接口的实现类分离开来。

接口中的方法再也不用渗入到类里了。

MOTO既可以用 WiredHeadSet 来听歌，也可以随时切换到BluetoothHeadSet来听歌。

// HeadSet.java
package designpatternsstructuralpatterns.bridge;

import java.util.List;

public interface HeadSet {
void play(List<String> songs);
}

// HeadSetImpl.java
package designpatternsstructuralpatterns.bridge;

import java.util.List;

class WiredHeadSet implements HeadSet {

@Override
public void play(List<String> songs) {
System.out.println("The WiredHeadSet is Playing: ");
for(String song: songs) {
System.out.println("[" + song + "]");
}
}
}

class BluetoothHeadSet implements HeadSet {

@Override
public void play(List<String> songs) {
System.out.println("The BluetoothHeadSet is Playing: ");
for(String song: songs) {
System.out.println("[" + song + "]");
}
}
}

// BridgeDemo.java
package designpatternsstructuralpatterns.bridge;

import java.util.*;

public class BridgeDemo {
public static void main(String[] args) {
List<String> songs = new ArrayList<>();
songs.add("I want it that way");
songs.add("Bye bye bye");
songs.add("Flying without wings");

Phone phone = new MOTO(songs);
phone.setHs(new WiredHeadSet());
phone.listen();

System.out.println();
System.out.println("WiredHeadSet >>>>>>> BluetoothHeadSet");
System.out.println();

phone.setHs(new BluetoothHeadSet());
phone.listen();
}
}

abstract class Phone {
protected HeadSet hs;

public HeadSet getHs() {
return hs;
}

public void setHs(HeadSet hs) {
this.hs = hs;
}

abstract void listen();
}

class MOTO extends Phone {
private List<String> songs;

public MOTO(List<String> songs) {
this.songs = songs;
}

@Override
void listen() {
hs.play(songs);
}
}

// output
The WiredHeadSet is Playing:
[I want it that way]
[Bye bye bye]
[Flying without wings]

WiredHeadSet >>>>>>> BluetoothHeadSet

The BluetoothHeadSet is Playing:
[I want it that way]
[Bye bye bye]
[Flying without wings]