SpringBoot中如何使用Assert进行断言校验

assert condition;
assert condition : errorMessage;

public class AssertExample {
    public static void main(String[] args) {
        int age = -5;
        assert age >= 0 : "年龄不能为负数: " + age;
        System.out.println("年龄是：" + age);
    }
}

java -ea AssertExample

<dependency>
    <groupId>org.springframework</groupId>
    <artifactId>spring-core</artifactId>
</dependency>

import org.springframework.util.Assert;

public class UserService {
    public void createUser(String username) {
        Assert.notNull(username, "用户名不能为空");
        // 创建用户逻辑
    }
}

import java.util.List;
import org.springframework.util.Assert;

public class OrderService {
    public void processOrders(List<String> orderIds) {
        Assert.notEmpty(orderIds, "订单ID列表不能为空");
        Assert.noNullElements(orderIds, "订单ID中不能包含null值");
        // 处理订单逻辑
    }
}

public class PaymentService {
    private boolean initialized = false;

    public void init() {
        // 初始化逻辑
        initialized = true;
    }

    public void pay() {
        Assert.state(initialized, "支付服务未初始化");
        // 支付逻辑
    }
}

@RestController
@RequestMapping("/users")
public class UserController {

    @PostMapping
    public ResponseEntity<Void> createUser(@RequestBody UserDto userDto) {
        Assert.notNull(userDto, "用户信息不能为空");
        Assert.hasText(userDto.getUsername(), "用户名不能为空");

        // 调用 service 保存用户
        return ResponseEntity.ok().build();
    }
}

@Service
public class OrderService {

    public void placeOrder(Order order) {
        Assert.notNull(order, "订单不能为空");
        Assert.notNull(order.getItems(), "订单商品列表不能为空");

        if (order.getItems().isEmpty()) {
            throw new IllegalArgumentException("订单必须包含至少一个商品");
        }

        // 下单逻辑
    }
}

@Repository
public class UserRepository {

    public void save(User user) {
        Assert.notNull(user, "用户实体不能为空");
        Assert.hasText(user.getEmail(), "邮箱不能为空");

        // 执行保存操作
    }
}