<project xmlns="http://maven.apache.org/POM/4.0.0"
         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
    <modelVersion>4.0.0</modelVersion>
    <groupId>com.example</groupId>
    <artifactId>spring-data-jpa-demo</artifactId>
    <version>1.0-SNAPSHOT</version>
    <parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.7.5</version>
    </parent>
    <dependencies>
        <!-- Spring Data JPA -->
        <dependency>
            <groupId>org.springframework.boot</groupId>
            <artifactId>spring-boot-starter-data-jpa</artifactId>
        </dependency>
        <!-- H2數(shù)據(jù)庫(kù)，用于測(cè)試 -->
        <dependency>
            <groupId>com.h2database</groupId>
            <artifactId>h2</artifactId>
            <scope>runtime</scope>
        </dependency>
    </dependencies>
    <build>
        <plugins>
            <plugin>
                <groupId>org.springframework.boot</groupId>
                <artifactId>spring-boot-maven-plugin</artifactId>
            </plugin>
        </plugins>
    </build>
</project>

package com.example.entity;
import javax.persistence.Entity;
import javax.persistence.GeneratedValue;
import javax.persistence.GenerationType;
import javax.persistence.Id;
import javax.persistence.Column;
@Entity
public class User {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    private Long id;
    @Column(name = "username")
    private String username;
    @Column(name = "email")
    private String email;
    // 構(gòu)造函數(shù)
    public User() {
    }
    public User(String username, String email) {
        this.username = username;
        this.email = email;
    }
    // Getters and Setters
    public Long getId() {
        return id;
    }
    public void setId(Long id) {
        this.id = id;
    }
    public String getUsername() {
        return username;
    }
    public void setUsername(String username) {
        this.username = username;
    }
    public String getEmail() {
        return email;
    }
    public void setEmail(String email) {
        this.email = email;
    }
}

package com.example.repository;
import com.example.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
public interface UserRepository extends JpaRepository<User, Long> {
    // 根據(jù)用戶名查詢用戶
    User findByUsername(String username);
}

package com.example.service;
import com.example.entity.User;
import com.example.repository.UserRepository;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;
@Service
public class UserService {
    @Autowired
    private UserRepository userRepository;
    public User createUser(User user) {
        return userRepository.save(user);
    }
}

public User getUserById(Long id) {
    return userRepository.findById(id).orElse(null);
}
public User getUserByUsername(String username) {
    return userRepository.findByUsername(username);
}

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

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

package com.example.repository;
import com.example.entity.User;
import org.springframework.data.jpa.repository.JpaRepository;
import org.springframework.data.jpa.repository.Query;
public interface UserRepository extends JpaRepository<User, Long> {
    // 根據(jù)用戶名查詢用戶
    User findByUsername(String username);
    // 自定義查詢：查詢所有郵箱以指定字符串結(jié)尾的用戶
    @Query("SELECT u FROM User u WHERE u.email LIKE %?1")
    java.util.List<User> findUsersByEmailEndingWith(String emailEnding);
}