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 理解生成器模式在于：一个对象若由多个部分组成，只要构建好这些部分然后拼接到一起就组成了一个完整的对象。比如一台电脑，它的类型可以不一样，可以是苹果的，可以是联想的，等等。同一款电脑它的组件也不一样，有的内存大一点，有的CPU高级点。如果把不同款式的电脑都封装成一个对象的话就比较复杂，使用生成器模式可以快速构建自己需要的对象。下面使用这个案例说明。

package Builder;public class Client {public static void main(String[] args) {Direct direct = new Direct();ComputerBulider computerBuliderA = new ComputerABuilder();direct.setCb(computerBuliderA);Computer computerA = direct.contructor();System.out.println(computerA.toString());ComputerBulider computerBuliderB = new ComputerBBuilder();direct.setCb(computerBuliderB);Computer computerB = direct.contructor();System.out.println(computerB.toString());}
}

package Builder;public class Computer {private String cpu;//中央处理器private String memory;//内存private String disk;//硬盘private String graphics;//显卡private String mainboard;//主板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 getDisk() {return disk;}public void setDisk(String disk) {this.disk = disk;}public String getGraphics() {return graphics;}public void setGraphics(String graphics) {this.graphics = graphics;}public String getMainboard() {return mainboard;}public void setMainboard(String mainboard) {this.mainboard = mainboard;}@Overridepublic String toString() {return "Computer{" +"cpu='" + cpu + '\'' +", memory='" + memory + '\'' +", disk='" + disk + '\'' +", graphics='" + graphics + '\'' +", mainboard='" + mainboard + '\'' +'}';}
}

package Builder;public class ComputerABuilder extends ComputerBulider{@Overridepublic void buildCpu() {computer.setCpu("CPUA");}@Overridepublic void buildMemory() {computer.setMemory("内存A");}@Overridepublic void buildDisk() {computer.setDisk("硬盘A");}@Overridepublic void buildGraphics() {computer.setGraphics("显卡A");}@Overridepublic void buildMainboard() {computer.setMainboard("主板A");}
}

package Builder;public class ComputerBBuilder extends ComputerBulider{@Overridepublic void buildCpu() {computer.setCpu("CPUB");}@Overridepublic void buildMemory() {computer.setMemory("内存B");}@Overridepublic void buildDisk() {computer.setDisk("硬盘B");}@Overridepublic void buildGraphics() {computer.setGraphics("显卡B");}@Overridepublic void buildMainboard() {computer.setMainboard("主板B");}
}

package Builder;public abstract class ComputerBulider {protected Computer computer = new Computer();public abstract void buildCpu();public abstract void buildMemory();public abstract void buildDisk();public abstract void buildGraphics();public abstract void buildMainboard();public Computer getComputer() {return computer;}
}

package Builder;public class Direct {private ComputerBulider cb;public void setCb(ComputerBulider cb) {this.cb = cb;}public Computer contructor() {cb.buildDisk();cb.buildGraphics();cb.buildCpu();cb.buildMainboard();cb.buildMemory();return cb.getComputer();}
}

所有的电脑都是一个产品Product，所有的组件都在这里声明。ConcreteBulider作用是构建电脑具体的部件，Direct作用是将部件组装，并提供方法可以让Client拿到电脑。在Client中声明了Direct和ConcreteBulider，将ConcreteBulider传入Direct中完成组装然后调用方法拿到电脑。