Java项目中如何做购物清单持久化_JSON与本地存储方式说明

public class ShoppingItem {
    private String name;
    private int quantity;
    private boolean purchased;

    // 构造方法
    public ShoppingItem() {}

    public ShoppingItem(String name, int quantity, boolean purchased) {
        this.name = name;
        this.quantity = quantity;
        this.purchased = purchased;
    }

    // Getter 和 Setter 方法
    public String getName() { return name; }
    public void setName(String name) { this.name = name; }

    public int getQuantity() { return quantity; }
    public void setQuantity(int quantity) { this.quantity = quantity; }

    public boolean isPurchased() { return purchased; }
    public void setPurchased(boolean purchased) { this.purchased = purchased; }
}

import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import java.util.List;

Gson gson = new GsonBuilder().setPrettyPrinting().create();
String json = gson.toJson(shoppingList); // shoppingList 是 List

List loadedList = gson.fromJson(json, new TypeToken>(){}.getType());

import java.nio.file.Files;
import java.nio.file.Paths;

Files.write(Paths.get("shopping_list.json"), json.getBytes());

String json = Files.readString(Paths.get("shopping_list.json"));

if (Files.exists(Paths.get("shopping_list.json"))) {
    String json = Files.readString(Paths.get("shopping_list.json"));
    // 反序列化
}

public class PersistenceManager {
    private static final String FILE_PATH = "shopping_list.json";
    private static final Gson gson = new GsonBuilder().setPrettyPrinting().create();

    public static void save(List list) throws IOException {
        String json = gson.toJson(list);
        Files.write(Paths.get(FILE_PATH), json.getBytes());
    }

    public static List load() throws IOException {
        if (!Files.exists(Paths.get(FILE_PATH))) {
            return new ArrayList<>();
        }
        String json = Files.readString(Paths.get(FILE_PATH));
        return gson.fromJson(json, new TypeToken>(){}.getType());
    }
}