前言
构建者模式，是用来构建我们的对象。如果我们构建的对象有很多属性值要设置，使用大量的setXX()，这样代码不利于阅读，也不整洁。
实现
我们假设有创建的是一个订单。使用构建者模式如下。PS:通常的构建者模式中是不提供setXX()方法，一旦对象构建以后就不允许修改，但是实际业务场景中有时候创建完一个对象，后续根据情形需要单独修改某个属性值，所以提供了setXX().
/**
* 订单
*/
public class Order {
/**
* 价格
*/
private Double price;
/**
* 订单号
*/
private String orderId;
/**
* 寄件人姓名
*/
private String sendMan;
/**
* 寄件人地址
*/
private String sendAddress;
/**
* 寄件人电话
*/
private String sendMobile;
/**
* 收件人
*/
private String receiveMan;
/**
* 收件人地址
*/
private String receiveAddress;
/**
* 收件人电话
*/
private String receiveMobile;
/**
* 备注
*/
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;
}
/**
* 静态方法获取bulider
* @return
*/
public static Builder Builder(){
return new Builder();
}
/**
* Builder是public static 内部类.
* 1 pulblic 为了扩大访问域，包外也可以
* 2 static 是为了Order方法需要通过静态方法获取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();
//后续业务场景需要，可以修改某个属性
order.setRemark("666");
System.out.println(order.getOrderId());
}
}
不重复造轮子，使用lombok
复杂的系统中，为了开发人员更专注于业务，不必要编写AllArgsConstructor，NoArgsConstructor,Builder，getter,setter，建议使用lombok。通过简单的注解，即可完成以上重复繁琐的工作，引入lombok后编译器在编译的时候会生成包含以上内容class文件，感兴趣的小伙伴可以看看引入lombok后生成的class文件
