设计模式 之建造者模式

建造者模式定义

将一个复杂对象的构建过程与它的表示分离。

适用场景

当一个类的构造函数参数个数超过4个，而且这些参数有些是可选的参数，考虑使用构造者模式。

@Data
public class Computer {
    private String cpu;
    private int usbCount;
    public static void main(String[] args) {
        Computer computer1 = new Builder().addCpu("Intel").addUsbCount(4).build();
        Computer computer2 = new Builder().addUsbCount(3).addCpu("AMD").build();
    }
}

public class Builder {
    private Computer computer = new Computer();
    public Builder addCpu(String cpu){
        computer.setCpu(cpu);
        return this;
    }
    public Builder addUsbCount(int usbCount){
        computer.setUsbCount(usbCount);
        return this;
    }
    public Computer build(){
        return computer;
    }
}

Spring 中应用

BeanDefinitionBuilder

OkHttpClient okHttpClient = new OkHttpClient.Builder()
        .connectTimeout(10, TimeUnit.SECONDS)
        .writeTimeout(10, TimeUnit.SECONDS)
        .readTimeout(10, TimeUnit.SECONDS)
        .build();