用流解决商品进货问题（菜菜，大佬帮帮）
每个商城都需要进货，而这些进货记录整理起来很不方便，本案例要求编写一个记录商城进货交易的程序，使用字节流将商场的进货信息记录在本地的csv文件中。程序具体要求如下：当用户输入商品编号时，后台会根据商品编号查询到相应商品信息，并打印商品信息。接着让用户输入需要进货的商品数量，程序将原有的库存数量与输入的数量相加，将相加后的结果信息保存至本地的csv文件中。
用着笨方法试着写了下，这里 csv 文件结构是这样的：
Id,Goods,Inventory
1,Banada,10
2,Apple,10
3,Durain,15
4,Orange,10
5,Strawberry,10
GoodsInventory.java 文件：
import java.io.*;
import java.nio.charset.StandardCharsets;
import java.util.Map;
import java.util.Scanner;
import java.util.TreeMap;
public class GoodsInventory {
private Map<Integer, Object[]> map = new TreeMap<>();
private Object[] head;
public boolean writeFile(String filePath, Map<Integer, Object[]> map) {
FileOutputStream fos = null;
try {
fos = new FileOutputStream(filePath);
fos.write(String.format("%s,%s,%s\n", head).getBytes(StandardCharsets.UTF_8));
for (Integer id : map.keySet()){
fos.write(String.format("%s,%s,%s\n", map.get(id)).getBytes(StandardCharsets.UTF_8));
}
System.out.println("库存文件更新成功！");
} catch (IOException e) {
throw new RuntimeException(e);
} finally {
if (fos != null){
try {
fos.close();
} catch (IOException e) {
throw new RuntimeException(e);
}
}
}
return false;
}
public boolean updateInventoryById(Integer id, Integer count){
Object[] obj = map.get(id);
if (obj == null){
return false;
}
Integer temp = (Integer) obj + count;
if (temp < 0){
System.out.println("库存不足！");
return false;
}
obj = (Integer) obj + count;
return true;
}
public Map<Integer, Object[]> readFile(String fileName){
FileInputStream fis = null;
BufferedReader br = null;
try {
fis = new FileInputStream(fileName);
br = new BufferedReader(new InputStreamReader(fis));
String data;
String[] str;
if ((data = br.readLine()) != null){
str = data.split(",");
head = str;
}
while ((data = br.readLine()) != null) {
str = data.split(",");
Object[] temp = {str, str, Integer.parseInt(str)};
map.put(Integer.parseInt(str), temp);
}
} catch (Exception e) {
throw new RuntimeException("文件未找到，请检查路径或文件名是否正确！");
} finally {
try {
if (br != null){
br.close();
} else if (fis != null)
fis.close();
} catch (Exception e) {
throw new RuntimeException(e);
}
}
return map;
}
public boolean printGoodsByIdData(Integer id){
Object[] obj = map.get(id);
if (obj == null){
System.out.println("错误：没有找到此ID商品项！");
System.out.print("请重新输入商品ID: ");
return false;
}
System.out.printf("%s\t %s\t %s\n", head);
System.out.printf("%s\t %s\t %s\n", map.get(id));
return true;
}
}
GoodsInventoryTest.java 测试程序：
import java.util.Map;
import java.util.Scanner;
public class GoodsInventoryTest {
public static void main(String[] args) {
Scanner scan = new Scanner(System.in);
String filePath = "./src/pers/uang/demo05/GoodsInventory.csv";
GoodsInventory inventory = new GoodsInventory();
Map<Integer , Object[]> map = inventory.readFile(filePath);
int id = -1;
boolean flag = false;
boolean isNew = false;
while (!flag){
System.out.print("请输入商品ID: ");
while (!flag) {
id = scan.nextInt();
scan.nextLine();
flag = inventory.printGoodsByIdData(id);
}
System.out.print("\n请输入需要更新的库存数量(负号表示库存减少):");
int count = scan.nextInt();
scan.nextLine();
if (inventory.updateInventoryById(id, count)) {
isNew = true;
System.out.println("\n更新成功！");
} else {
System.out.println("\n更新失败！");
}
System.out.print("还需要更新其它商品的库存记录吗(回车则继续, 任意输入退出系统): ");
String isExit = scan.nextLine();
if ("".equals(isExit)){
flag = false;
}
}
// 写入文件中去
if (isNew){
inventory.writeFile(filePath, map);
} else {
System.out.println("库存暂未更新, 无需写入！");
}
}
}
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