Java Stream MapReduce大数据开发模型

实现一个购买商品后,对数据进行处理统计的功能.

将购买的商品信息保存在Orders类中

public class Orders {private String name;private double price;private int amount;public Orders(String name, double price, int amount) {this.name = name;this.price = price;this.amount = amount;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public int getAmount() {return amount;}public void setAmount(int amount) {this.amount = amount;}

通过map()处理数据,输出购买每一件商品的总价

public static void main(String[] args) {List<Orders> list = new ArrayList<>();list.add(new Orders("dq csdn", 60.00, 80));list.add(new Orders("dq android", 100.20, 73));list.add(new Orders("dq java", 72.02, 15));//计算购买每一件商品的总价list.stream().map((x) -> x.getAmount() * x.getPrice()).forEach(System.out::println);}

通过reduce()对map()处理后的数据进行统计

 double all = list.stream().map((x) -> x.getAmount() * x.getPrice()).reduce((x, y) -> x + y).get();System.out.println(String.format("%.2f", all));

使用DoubleStream接口中DoubleSummaryStatistics类进行数据统计

        DoubleSummaryStatistics statistics=list.stream().mapToDouble((x)->x.getAmount()* x.getPrice()).summaryStatistics();System.out.println("商品品种"+statistics.getCount()+"商品总花费"+statistics.getSum()+"商品平均花费"+statistics.getAverage()+"最高花费"+statistics.getMax()+"最低花费"+statistics.getMin());

总代码:

import java.util.ArrayList;
import java.util.DoubleSummaryStatistics;
import java.util.List;public class Orders {private String name;private double price;private int amount;public Orders(String name, double price, int amount) {this.name = name;this.price = price;this.amount = amount;}public String getName() {return name;}public void setName(String name) {this.name = name;}public double getPrice() {return price;}public void setPrice(double price) {this.price = price;}public int getAmount() {return amount;}public void setAmount(int amount) {this.amount = amount;}public static void main(String[] args) {List<Orders> list = new ArrayList<>();list.add(new Orders("dq csdn", 60.00, 80));list.add(new Orders("dq android", 100.20, 73));list.add(new Orders("dq java", 72.02, 15));DoubleSummaryStatistics statistics=list.stream().mapToDouble((x)->x.getAmount()* x.getPrice()).summaryStatistics();System.out.println("商品品种"+statistics.getCount()+"商品总花费"+statistics.getSum()+"商品平均花费"+statistics.getAverage()+"最高花费"+statistics.getMax()+"最低花费"+statistics.getMin());}
}