设计模式-建造者模式

核心思想

• 抽取共同的行为，允许使用者指定复杂对象的类型和内容，不需要了解内部的构建细节
• 使用多个简单的行为构建一个复杂的对象，将对象的构建过程和它的表示分离，同样的构建过程可以创建不同的表示

优缺点

优点

• 使用者不需要知道具体内部组成细节，产品本身与创建过程解耦
• 具体建造者每个都是独立的，相互无关，不同的是控制产品的创建过程
• 新增具体建造者不需要修改原来类的代码

缺点

• 建造者所创建的产品一般要具有比较多的共同点，差异大的话不建议使用

代码示例

指挥者代码

/*** 指挥者*/
public class Director {/*** 构建对象* @param builder* @return*/public Computer createComputer(Builder builder){builder.buildMemory();builder.buildCpu();builder.buildMainboard();builder.buildDisk();builder.buildPower();return builder.getComputer();}
}

抽象建造者

/*** 建造者的公共方法*/
public interface Builder {/***方法*/void buildCpu();void buildMainboard();void buildDisk();void buildPower();void buildMemory();Computer getComputer();
}

具体建造者

public class HighComputerBuilder implements Builder{private Computer computer = new Computer();@Overridepublic void buildCpu() {computer.setCpu("高配 CPU");}@Overridepublic void buildMainboard() {computer.setMainboard("高配 主板");}@Overridepublic void buildDisk() {computer.setDisk("高配 磁盘");}@Overridepublic void buildPower() {computer.setPower("高配 电源");}@Overridepublic void buildMemory() {computer.setMemory("高配 内存");}@Overridepublic Computer getComputer() {return computer;}
}

public class LowComputerBuilder implements Builder{private Computer computer = new Computer();@Overridepublic void buildCpu() {computer.setCpu("低配 CPU");}@Overridepublic void buildMainboard() {computer.setMainboard("低配 主板");}@Overridepublic void buildDisk() {computer.setDisk("低配 磁盘");}@Overridepublic void buildPower() {computer.setPower("低配 电源");}@Overridepublic void buildMemory() {computer.setMemory("低配 内存");}@Overridepublic Computer getComputer() {return computer;}
}

产品

public class Computer {private String cpu;private String memory;private String mainboard;private String disk;private String power;public String getCpu() {return cpu;}public void setCpu(String cpu) {this.cpu = cpu;}public String getMemory() {return memory;}public void setMemory(String memory) {this.memory = memory;}public String getMainboard() {return mainboard;}public void setMainboard(String mainboard) {this.mainboard = mainboard;}public String getDisk() {return disk;}public void setDisk(String disk) {this.disk = disk;}public String getPower() {return power;}public void setPower(String power) {this.power = power;}@Overridepublic String toString() {return "Computer{" +"cpu='" + cpu + '\'' +", memory='" + memory + '\'' +", mainboard='" + mainboard + '\'' +", disk='" + disk + '\'' +", power='" + power + '\'' +'}';}
}

测试

public class AppRun {public static void main(String[] args) {Director director = new Director();Computer computer = director.createComputer(new HighComputerBuilder());System.out.println(computer);}
}

public class AppRun {public static void main(String[] args) {Director director = new Director();Computer computer = director.createComputer(new LowComputerBuilder());System.out.println(computer);}
}