Java简单实例--小超市

import java.io.File;import java.io.FileInputStream;import java.io.FileNotFoundException;import java.io.FileOutputStream;import java.io.IOException;import java.util.ArrayList;import java.util.List;import java.util.Scanner;class Product{private int id;private String name;private double price;private int store;public int getId() {return id;}public void setId(int id) {this.id = id;}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 getStore() {return store;}public void setStore(int store) {this.store = store;}public Product(int id, String name, double price, int store) {super();this.id = id;this.name = name;this.price = price;this.store = store;}public Product() {super();}@Overridepublic String toString() {return "product [id=" + id + ", name=" + name + ", price=" + price + ", store=" + store + "]";}}class SuperMarket{private List<Product> products = new ArrayList<Product>();public SuperMarket(){}public List<Product> getProducts() {return products;}public void setProducts(List<Product> products) {this.products = products;}}class Manager{private SuperMarket market;private File file;private void init(String[] strs){int id = 0;String name = null;double price = 0;int store = 0;List<Product> products = new ArrayList<Product>();for(int i = 0; i < strs.length; i++){if((i+1)%4==1){id = Integer.parseInt(strs[i]);}if((i+1)%4==2){name = strs[i];}if((i+1)%4==3){price = Double.valueOf(strs[i]);}if((i+1)%4==0){store = Integer.parseInt(strs[i]);Product product = new Product(id, name, price, store);products.add(product);}}market.setProducts(products);}private void save(){int id;String name;double price;int store;String str = new String("");FileOutputStream fos = null;try {fos = new FileOutputStream(file);} catch (FileNotFoundException e) {e.printStackTrace();}for(int i = 0 ;i < market.getProducts().size();i++){id = market.getProducts().get(i).getId();name = market.getProducts().get(i).getName();price = market.getProducts().get(i).getPrice();store = market.getProducts().get(i).getStore();str += String.valueOf(id) + "#" + name + "#" + String.valueOf(price) + "#" + String.valueOf(store) + "#";}byte[] b = new byte[str.length()+1];b = str.getBytes();try {fos.write(b);fos.close();} catch (IOException e) {e.printStackTrace();}}public Manager(){market = new SuperMarket();file = new File("market.txt");}public SuperMarket getMarket() {return market;}public void setMarket(SuperMarket market) {this.market = market;}public void query(){System.out.println(" id name price store");FileInputStream fis = null;String str = null;try {fis = new FileInputStream(file);int length = fis.available();byte[] b = new byte[length];fis.read(b);str = new String(b,"GB2312");} catch (Exception e) {e.printStackTrace();}finally{try {fis.close();} catch (IOException e) {e.printStackTrace();}}String[] strs = str.split("#");for(int i = 0 ; i < strs.length ; i++){System.out.print(" "+strs[i]);if((i+1)%4!=0){System.out.print("");}else{System.out.println();}}init(strs);}public void update(){query();System.out.println("输入要修改的产品id");int n;Scanner sc = new Scanner(System.in);n = sc.nextInt();String name;double price;int store;System.out.println("input the info:");System.out.print("name:");name = sc.next();System.out.print("price:");price = sc.nextDouble();System.out.print("store:");store = sc.nextInt();market.getProducts().get(n-1).setName(name);market.getProducts().get(n-1).setPrice(price);market.getProducts().get(n-1).setStore(store);save();}public void add(){System.out.println("现在有如下产品：");query();System.out.println("输入你想添加的产品：");Scanner sc = new Scanner(System.in);String name;double price;int store;System.out.println("input the info:");System.out.print("name:");name = sc.next();System.out.print("price:");price = sc.nextDouble();System.out.print("store:");store = sc.nextInt();int id = market.getProducts().size() + 1;Product product = new Product(id, name, price, store);market.getProducts().add(product);save();}}public class Main {public static void main(String[] args){Manager manager = new Manager();int n = 0;Scanner sc = new Scanner(System.in);while(n!=4){System.out.println("输入你的操作：");System.out.println("1.query2.update3.add4.exit");n = sc.nextInt();switch(n){case 1 : manager.query();break;case 2 : manager.update();break;case 3 : manager.add();break;case 4 : break;}System.out.println("\n");}sc.close();}}