需求是这样的：
我需要打造一个商城，且商城是注册过的读一无二的，就像是万达或者沃尔玛。商城每天都提供食物和衣服，但是为了提供个性化的促销服务，商城每天提供不同的廉价商品搭配。
比如：
day1:（提供）调料品
day2:（提供）床上用品+婴儿用品+家具
day3:（提供）厨具+洗护用品
好了，需求就是这样。不废话，直接上代码。
/**
* Created by zhangxiang on 16-9-22.
*/
public class Mall{
private int food;
private int clothes;
private int seasoning;
private int bedding;
private int babyProducts;
private int furniture;
private int cook;
private int washProducts;
private static Mall sInstance = null;
public static synchronized Mall getInstance(Builder builder) {
if (sInstance == null) {
sInstance = new Mall(builder);
}else {
//这里注意else重新初始化了Mall的内容，但是保持了Mall为单例
sInstance.setMall(builder);
}
return sInstance;
}
public static class Builder {
private final int food;
private final int clothes;
private int seasoning = 0;
private int bedding = 0;
private int babyProducts = 0;
private int furniture = 0;
private int cook = 0;
private int washProducts = 0;
//初始化必备商品
public Builder(int food,int clothes){
this.food = food;
this.clothes = clothes;
}
public Builder seasoning(int seasoning){
this.seasoning = seasoning;
return this;
}
public Builder bedding(int bedding){
this.bedding = bedding;
return this;
}
public Builder babyProducts(int babyProducts){
this.babyProducts = babyProducts;
return this;
}
public Builder furniture(int furniture){
this.furniture = furniture;
return this;
}
public Builder cook(int cook){
this.cook = cook;
return this;
}
public Builder washProducts(int washProducts){
this.washProducts = washProducts;
return this;
}
//返回唯一商城
public Mall build(){
return Mall.getInstance(this);
}
}
private Mall(Builder builder){
food = builder.food;
clothes = builder.clothes;
seasoning = builder.seasoning;
bedding = builder.bedding;
babyProducts = builder.babyProducts;
furniture = builder.furniture;
cook = builder.cook;
washProducts = builder.washProducts;
}
private void setMall(Builder builder){
food = builder.food;
clothes = builder.clothes;
seasoning = builder.seasoning;
bedding = builder.bedding;
babyProducts = builder.babyProducts;
furniture = builder.furniture;
cook = builder.cook;
washProducts = builder.washProducts;
}
public void printProducts(int day)
{
System.out.print(this.toString()+"---------"+day+"-----------\\n");
System.out.println("food num is:" +this.food+"\\n"+
"clothes num is:"+this.clothes+"\\n"+
"seasoning num is:"+this.seasoning+"\\n"+
"bedding num is:"+this.bedding+"\\n"+
"babyProducts num is:"+this.babyProducts+"\\n"+
"furniture num is:"+this.furniture+"\\n"+
"cook num is:"+this.cook+"\\n"+
"washProducts num is:"+this.washProducts+"\\n");
}
public static void main(String[] args) {
/** 第一天：（食物+衣物）+调料品 **/
Mall dayOne = new Mall.Builder(240,80).seasoning(100).build();
dayOne.printProducts(1);
/** 第二天：（食物+衣物）+床上用品+婴儿用品+家具 **/
Mall dayTwo = new Mall.Builder(300,100).bedding(20).babyProducts(30).furniture(50).build();
dayTwo.printProducts(2);
/** 第三天：（食物+衣物）+厨具+洗护用品 **/
Mall dayThree = new Builder(400,20).cook(300).washProducts(50).build();
dayThree.printProducts(3);
}
}
打印结果：
Mall@3ba76e19可以看出都是同一个实例
Mall@3ba76e19---------1-----------
food num is:240
clothes num is:80
seasoning num is:100
bedding num is:0
babyProducts num is:0
furniture num is:0
cook num is:0
washProducts num is:0
Mall@3ba76e19---------2-----------
food num is:300
clothes num is:100
seasoning num is:0
bedding num is:20
babyProducts num is:30
furniture num is:50
cook num is:0
washProducts num is:0
Mall@3ba76e19---------3-----------
food num is:400
clothes num is:20
seasoning num is:0
bedding num is:0
babyProducts num is:0
furniture num is:0
cook num is:300
washProducts num is:50
很好，虽然你不是王思聪，但是你和他爸一样有一个个性化商城了。
