基于Spring Boot的旧物置换网站

构建一个基于Spring Boot的旧物置换网站是一个很好的项目，可以帮助你学习如何设计和实现一个完整的Web应用程序。以下是一个简化版的示例，展示了如何搭建这样一个系统的框架。

1. 创建Spring Boot项目

首先，你需要创建一个新的Spring Boot项目。可以使用Spring Initializr来快速生成基础项目：

项目类型：Maven Project
依赖项：Spring Web, Spring Data JPA, Thymeleaf（前端模板引擎）

2. 设计数据库模型

对于一个旧物置换网站来说，至少需要以下几个实体模型：

用户（User）

@Entity
public class User {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;@Column(nullable = false, unique = true)private String username;@Column(nullable = false)private String password;@Column(nullable = false, unique = true)private String email;// Getters and Setters...
}

物品（Item）

@Entity
public class Item {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;@Column(nullable = false)private String title;@Column(nullable = false)private String description;@Column(nullable = false)private Double askingPrice; // 请求价格@ManyToOne(fetch = FetchType.LAZY)@JoinColumn(name = "owner_id")private User owner;@OneToOne(mappedBy = "item", cascade = CascadeType.ALL, fetch = FetchType.LAZY)private Exchange exchange;// Getters and Setters...
}

交换（Exchange）

@Entity
public class Exchange {@Id@GeneratedValue(strategy = GenerationType.IDENTITY)private Long id;@OneToOne(mappedBy = "exchange", cascade = CascadeType.ALL)private Item item;@Column(nullable = false)private Boolean isAvailable; // 是否可用@ManyToOne(fetch = FetchType.LAZY)@JoinColumn(name = "interested_user_id")private User interestedUser;// Getters and Setters...
}

3. 创建REST API

接下来，我们需要创建一些RESTful API来处理用户注册、物品发布、物品交换等功能。

用户控制器（UserController）

@RestController
@RequestMapping("/api/users")
public class UserController {@Autowiredprivate UserService userService;@PostMapping("/register")public ResponseEntity<User> register(@RequestBody User user) {User registeredUser = userService.register(user.getUsername(), user.getPassword(), user.getEmail());return new ResponseEntity<>(registeredUser, HttpStatus.CREATED);}@PostMapping("/login")public ResponseEntity<String> login(@RequestParam String username, @RequestParam String password) {String token = userService.login(username, password);if (token != null) {return new ResponseEntity<>(token, HttpStatus.OK);} else {return new ResponseEntity<>(HttpStatus.UNAUTHORIZED);}}// 更多功能...
}

物品控制器（ItemController）

@RestController
@RequestMapping("/api/items")
public class ItemController {@Autowiredprivate ItemService itemService;@PostMappingpublic ResponseEntity<Item> createItem(@RequestBody Item item) {Item newItem = itemService.create(item);return new ResponseEntity<>(newItem, HttpStatus.CREATED);}@GetMapping("/{itemId}")public ResponseEntity<Item> getItemById(@PathVariable Long itemId) {Item item = itemService.findById(itemId);if (item != null) {return new ResponseEntity<>(item, HttpStatus.OK);} else {return new ResponseEntity<>(HttpStatus.NOT_FOUND);}}// 更多功能...
}

交换控制器（ExchangeController）

@RestController
@RequestMapping("/api/exchanges")
public class ExchangeController {@Autowiredprivate ExchangeService exchangeService;@PostMapping("/{itemId}")public ResponseEntity<Exchange> requestExchange(@PathVariable Long itemId, @RequestParam String userId) {Exchange newExchange = exchangeService.requestExchange(itemId, userId);return new ResponseEntity<>(newExchange, HttpStatus.CREATED);}@PutMapping("/{exchangeId}/accept")public ResponseEntity<Exchange> acceptExchange(@PathVariable Long exchangeId) {Exchange acceptedExchange = exchangeService.acceptExchange(exchangeId);if (acceptedExchange != null) {return new ResponseEntity<>(acceptedExchange, HttpStatus.OK);} else {return new ResponseEntity<>(HttpStatus.BAD_REQUEST);}}// 更多功能...
}

4. 安全性

为了保护API，可以使用Spring Security来实现认证和授权。

配置安全（SecurityConfig.java）

@Configuration
@EnableWebSecurity
public class SecurityConfig extends WebSecurityConfigurerAdapter {@Overrideprotected void configure(HttpSecurity http) throws Exception {http.csrf().disable().authorizeRequests().antMatchers("/api/users/register").permitAll().antMatchers("/api/users/login").permitAll().anyRequest().authenticated().and().httpBasic();}
}

5. 前端

前端可以使用Thymeleaf或者其他前端框架（如React、Vue.js等）来构建用户界面。

示例页面（index.html）

<!DOCTYPE html>
<html xmlns:th="http://www.thymeleaf.org">
<head><title>Old Item Exchange Platform</title>
</head>
<body>
<h1>Welcome to Old Item Exchange Platform!</h1>
<div><table><thead><tr><th>Title</th><th>Description</th><th>Asking Price</th><th>Action</th></tr></thead><tbody><tr th:each="item : ${items}"><td th:text="${item.title}"></td><td th:text="${item.description}"></td><td th:text="${item.askingPrice}"></td><td><button th:if="${item.exchange.isAvailable}" th:onclick="|requestExchange('${item.id}')|">Request Exchange</button></td></tr></tbody></table>
</div><script>function requestExchange(itemId) {// AJAX call to request an exchange for the item}
</script>
</body>
</html>