ideaJAVA数据库增删查改完整代码

在IntelliJ IDEA中编写Java代码连接数据库并完成基本的增删查改操作，通常会涉及使用Java Persistence API (JPA) 或 JDBC (Java Database Connectivity)。以下是使用JPA的一个简单示例：

首先，确保已经添加了JPA依赖（如果你使用Maven或Gradle）：

<!-- Maven -->
<dependency>
    <groupId>org.springframework.boot</groupId>
    <artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>

// Gradle
implementation 'org.springframework.boot:spring-boot-starter-data-jpa'

然后创建一个实体类（如User.java）：

import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;

@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    private String name;
    private String email;

    // getters and setters
}

配置数据源和JPA：

@Configuration
@EnableJpaRepositories(basePackages = "com.example.demo.repository")
@EntityScan("com.example.demo.entity") // 扫描entity包
public class JpaConfig {
    @Value("${spring.datasource.url}")
    private String url;

    @Value("${spring.datasource.username}")
    private String username;

    @Value("${spring.datasource.password}")
    private String password;

    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("com.mysql.cj.jdbc.Driver"); // 替换为实际驱动
        dataSource.setUrl(url);
        dataSource.setUsername(username);
        dataSource.setPassword(password);
        return dataSource;
    }

    @Bean
    public PlatformTransactionManager transactionManager(DataSource dataSource) {
        return new JpaTransactionManager(entityManagerFactory());
    }

    @Bean
    public LocalContainerEntityManagerFactoryBean entityManagerFactory() {
        LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();
        factory.setDataSource(dataSource());
        factory.packaged扫面策略改为"com.example.demo.entity"; // 替换为实际的包名
        factory.setJpaVendorAdapter(new HibernateJpaVendorAdapter());
        factory.setJpaProperties(hibernateProperties());
        return factory;
    }

    private Map<String, Object> hibernateProperties() {
        Map<String, Object> properties = new HashMap<>();
        properties.put("hibernate.dialect", "org.hibernate.dialect.MySQL5InnoDBDialect");
        properties.put("hibernate.show_sql", true); // 开启调试模式打印SQL
        return properties;
    }
}

最后，在Repository接口和Service层实现CRUD操作（假设UserRepository.java和UserService.java）：

// UserRepository.java
public interface UserRepository extends JpaRepository<User, Long> {
}

// UserService.java
@Service
public class UserService {
    private final UserRepository userRepository;

    public UserService(UserRepository userRepository) {
        this.userRepository = userRepository;
    }

    public User createUser(User user) {
        return userRepository.save(user);
    }

    public Optional<User> getUser(Long id) {
        return userRepository.findById(id);
    }

    public void updateUser(User user) {
        userRepository.save(user);
    }

    public void deleteUser(Long id) {
        userRepository.deleteById(id);
    }
}

为了测试这些操作，你可以创建一个Controller层（如UserController.java）：

@RestController
@RequestMapping("/users")
public class UserController {
    private final UserService userService;

    public UserController(UserService userService) {
        this.userService = userService;
    }

    // ... 添加对应HTTP映射的方法，例如 POST、GET、PUT 和 DELETE 请求
}

这只是一个简单的例子，实际应用中可能需要处理事务、错误处理和其他细节。