Builder模式如何在Java中实现

这篇文章给大家介绍Builder模式如何在Java中实现，内容非常详细，感兴趣的小伙伴们可以参考借鉴，希望对大家能有所帮助。

Pre Java8

我们先来看下在Java8之前的Builder模式

public class Order { private String code; private List<String> offers; private Map<String, Object> features; public static Order.Builder builder(){  return new Builder(); } //省略getter setter public static class Builder {  private OrderState orderState = new OrderState();  private static final BeanCopier orderCopier = BeanCopier.create(OrderState.class, Order1.class, false);  private class OrderState {   private String code;   private Map<String, Object> features;   private List<String> offers;   //省略getter setter  }  public Builder code(String code) {   orderState.code = code;   return this;  }  public Builder features(Map<String, Object> features) {   orderState.features = features;   return this;  }  public <T> Builder feature(String key, T obj) {   if (orderState.features == null) {    orderState.features = new HashMap<>();   }   orderState.features.put(key, obj);   return this;  }  public Builder offers(List<String> offers) {   orderState.offers = offers;   return this;  }  public Builder offer(String offer) {   if (orderState.offers == null) {    orderState.offers = new ArrayList<>();   }   orderState.offers.add(offer);   return this;  }  public Order build() {   Order order = new Order();   orderCopier.copy(orderState, order1, null);   orderState = null;   return order;  } }}