Hibernate的Annotation版Hello world实例

下面我将为你详细讲解“Hibernate的Annotation版Hello world实例”的完整攻略：

1. 构建项目

首先，我们需要构建一个Maven项目，在项目的pom.xml文件中添加相关依赖：

<dependencies>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-core</artifactId>
        <version>5.4.28.Final</version>
    </dependency>
    <dependency>
        <groupId>org.hibernate</groupId>
        <artifactId>hibernate-entitymanager</artifactId>
        <version>5.4.28.Final</version>
    </dependency>
    <dependency>
        <groupId>com.h2database</groupId>
        <artifactId>h2</artifactId>
        <version>1.4.200</version>
    </dependency>
</dependencies>

2. 创建Java实体类

创建一个Java实体类Student，并添加注解@Entity标识它是一个实体类，@Table指定表名，@Id标识主键，@GeneratedValue指定主键生成策略，@Column指定属性类型和列名。

@Entity
@Table(name = "student")
public class Student {
    @Id
    @GeneratedValue(strategy = GenerationType.IDENTITY)
    @Column(name = "id")
    private int id;

    @Column(name = "name")
    private String name;

    @Column(name = "age")
    private int age;

    public int getId() {
        return id;
    }

    public void setId(int id) {
        this.id = id;
    }

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

3. 配置数据源和Hibernate的注解配置文件

在src/main/resources目录下创建一个名为application.properties的文件，配置数据源和Hibernate的注解配置信息：

spring.datasource.driver-class-name=org.h2.Driver
spring.datasource.url=jdbc:h2:mem:testdb
spring.datasource.username=sa
spring.datasource.password=

spring.jpa.database-platform=org.hibernate.dialect.H2Dialect
spring.jpa.generate-ddl=true
spring.jpa.hibernate.ddl-auto=create

hibernate.format_sql=true
hibernate.hbm2ddl.auto=create

4. 创建DAO层代码

需要创建一个接口StudentDao，定义CRUD操作的接口方法。

public interface StudentDao {
    void save(Student student);

    List<Student> getAll();
}

并创建一个实现类StudentDaoImpl，使用@Repository注解标识它是一个DAO层的实现类，使用@PersistenceContext注解注入EntityManager对象。

@Repository
public class StudentDaoImpl implements StudentDao {
    @PersistenceContext
    private EntityManager entityManager;

    @Override
    public void save(Student student) {
        entityManager.persist(student);
    }

    @Override
    public List<Student> getAll() {
        TypedQuery<Student> query = entityManager.createQuery("select s from Student s", Student.class);
        return query.getResultList();
    }
}

5. 编写测试用例

创建一个测试类StudentDaoImplTest，测试学生的新增和查询。

@RunWith(SpringRunner.class)
@SpringBootTest
public class StudentDaoImplTest {
    @Autowired
    private StudentDao studentDao;

    @Test
    public void testSave() {
        Student student = new Student();
        student.setName("张三");
        student.setAge(18);
        studentDao.save(student);
        Assert.assertTrue(student.getId() > 0);
    }

    @Test
    public void testGetAll() {
        List<Student> studentList = studentDao.getAll();
        Assert.assertFalse(studentList.isEmpty());
    }
}

6. 运行测试用例

最后运行测试用例，测试结果应该如下：

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running com.example.demo.dao.StudentDaoImplTest
Hibernate: 

    create table student (
       id integer generated by default as identity (start with 1),
        age integer not null,
        name varchar(255),
        primary key (id)
    )
Hibernate: 
    insert 
    into
        student
        (age, name, id) 
    values
        (?, ?, ?)
Hibernate: 
    select
        student0_.id as id1_0_,
        student0_.age as age2_0_,
        student0_.name as name3_0_ 
    from
        student student0_
[INFO] Tests run: 2, Failures: 0, Errors: 0, Skipped: 0, Time elapsed: 1.194 s - in com.example.demo.dao.StudentDaoImplTest
[INFO]