前言

構(gòu)建者模式，是用來構(gòu)建我們的對象。如果我們構(gòu)建的對象有很多屬性值要設(shè)置，使用大量的setXX()，這樣代碼不利于閱讀，也不整潔。

實(shí)現(xiàn)

我們假設(shè)有創(chuàng)建的是一個(gè)訂單。使用構(gòu)建者模式如下。PS:通常的構(gòu)建者模式中是不提供setXX()方法，一旦對象構(gòu)建以后就不允許修改，但是實(shí)際業(yè)務(wù)場景中有時(shí)候創(chuàng)建完一個(gè)對象，后續(xù)根據(jù)情形需要單獨(dú)修改某個(gè)屬性值，所以提供了setXX().

/**
  * 訂單
 */
public class Order {
/**
 * 價(jià)格
 */
private Double price;
/**
 * 訂單號
 */
private String orderId;
/**
 * 寄件人姓名
 */
private String sendMan;
/**
 * 寄件人地址
 */
private String sendAddress;
/**
 * 寄件人電話
 */
private String sendMobile;
/**
 * 收件人
 */
private String receiveMan;
/**
 * 收件人地址
 */
private String receiveAddress;
/**
 * 收件人電話
 */
private String receiveMobile;
/**
 * 備注
 */
private String remark;

public Double getPrice() {
    return price;
}

public void setPrice(Double price) {
    this.price = price;
}

public String getOrderId() {
    return orderId;
}

public void setOrderId(String orderId) {
    this.orderId = orderId;
}

public String getSendMan() {
    return sendMan;
}

public void setSendMan(String sendMan) {
    this.sendMan = sendMan;
}

public String getSendAddress() {
    return sendAddress;
}

public void setSendAddress(String sendAddress) {
    this.sendAddress = sendAddress;
}

public String getSendMobile() {
    return sendMobile;
}

public void setSendMobile(String sendMobile) {
    this.sendMobile = sendMobile;
}

public String getReceiveMan() {
    return receiveMan;
}

public void setReceiveMan(String receiveMan) {
    this.receiveMan = receiveMan;
}

public String getReceiveAddress() {
    return receiveAddress;
}

public void setReceiveAddress(String receiveAddress) {
    this.receiveAddress = receiveAddress;
}

public String getReceiveMobile() {
    return receiveMobile;
}

public void setReceiveMobile(String receiveMobile) {
    this.receiveMobile = receiveMobile;
}

public String getRemark() {
    return remark;
}

public void setRemark(String remark) {
    this.remark = remark;
}
/**
 * 靜態(tài)方法獲取bulider
 * @return
 */
public static Builder Builder(){
    return new Builder();
}
  /**
 * Builder是public static 內(nèi)部類.
 * 1 pulblic 為了擴(kuò)大訪問域，包外也可以
 * 2 static 是為了Order方法需要通過靜態(tài)方法獲取Builder
 */
public static class Builder{
    private Double price;
    private String orderId;
    private String sendMan;
    private String sendAddress;
    private String sendMobile;
    private String receiveMan;
    private String receiveAddress;
    private String receiveMobile;
    private String remark;
    public Builder price(Double price){
        this.price = price;
        return this;
    }
    public Builder orderId(String orderId){
        this.orderId = orderId;
        return this;
    }
    public Builder sendMan(String sendMan){
        this.sendMan = sendMan;
        return this;
    }
    public Builder sendAddress(String sendAddress){
        this.sendAddress = sendAddress;
        return this;
    }
    public Builder sendMobile(String sendMobile){
        this.sendMobile = sendMobile;
        return this;
    }
    public Builder receiveMan(String receiveMan){
        this.receiveMan = receiveMan;
        return this;
    }
    public Builder receiveAddress(String receiveAddress){
        this.receiveAddress = receiveAddress;
        return this;
    }

    public Builder receiveMobile(String receiveMobile){
        this.receiveMobile = receiveMobile;
        return this;
    }
    public Builder remark(String remark){
        this.remark = remark;
        return this;
    }
    public Order build(){
        Order order = new Order();
        order.orderId = this.orderId;
        order.price = this.price;
        order.receiveAddress = this.receiveAddress;
        order.receiveMan = this.receiveMan;
        order.receiveMobile = this.receiveMobile;
        order.price = this.price;
        order.sendAddress = this.sendAddress;
        order.sendMan = this.sendMan;
        order.sendMobile = this.sendMobile;
        order.remark = this.remark;
        return order;
        
    }

}
}

使用方式：

public class DesignPatternApplication {
public static void main(String[] args) {
    Order order = Order.Builder().orderId("123").price(12.4).receiveMan("dd")
            .receiveAddress("dd").sendAddress("dd").remark("ddada").build();
    //后續(xù)業(yè)務(wù)場景需要，可以修改某個(gè)屬性
    order.setRemark("666");
    System.out.println(order.getOrderId());
}
}

不重復(fù)造輪子，使用lombok

復(fù)雜的系統(tǒng)中，為了開發(fā)人員更專注于業(yè)務(wù)，不必要編寫AllArgsConstructor，NoArgsConstructor,Builder，getter,setter，建議使用lombok。通過簡單的注解，即可完成以上重復(fù)繁瑣的工作，引入lombok后編譯器在編譯的時(shí)候會(huì)生成包含以上內(nèi)容class文件，感興趣的小伙伴可以看看引入lombok后生成的class文件