基礎(chǔ)

Spring data 提供一個核心接口 CrudRepository<T, ID extends Serializable> 用來提供訪問數(shù)據(jù)庫的基本方法募强，T是訪問數(shù)據(jù)庫的實體類负蠕，ID是數(shù)據(jù)庫主鍵數(shù)據(jù)類型

public interface CrudRepository<T, ID extends Serializable> extends Repository<T, ID> {
 
  <S extends T> S save(S entity);      ①
 
  Optional<T> findById(ID primaryKey); ②
 
  Iterable<T> findAll();               ③
 
  long count();                        ④
 
  void delete(T entity);               ⑤
 
  boolean existsById(ID primaryKey);   ⑥
 
  // … more functionality omitted.
}

① 保存數(shù)據(jù)
② 根據(jù)ID值查找數(shù)據(jù)
③ 返回所有數(shù)據(jù)
④ 返回數(shù)據(jù)的數(shù)量
⑤ 刪除提供的數(shù)據(jù)
⑥ 提供的數(shù)據(jù)是否存在

Spring Data 已經(jīng)實現(xiàn)了接口的方法，在使用中，只需要提供繼承CrudRepository的接口硫眯，不需要自己實現(xiàn)相同的方法

下面進行測試

創(chuàng)建數(shù)據(jù)表

CREATE DATABASE jpa_demo;
USE jpa_demo;
CREATE TABLE t_user(
    id BIGINT PRIMARY KEY AUTO_INCREMENT,
    firstName VARCHAR(20) NOT NULL,
    lastName VARCHAR(20) NOT NULL
) ENGINE = INNODB;

配置Spring Data忘朝，這里采用JavaConfig配置

@Configuration                                   // 這里聲明這個文件是配置文件
@EnableJpaRepositories({"com.lee.repository"})   // 這里制定repository所在的包(package)
public class DataSourceConfig {
 
  @Bean
  public DataSource dataSource() {
      Properties prop = new Properties();
      DriverManagerDataSource ds = new DriverManagerDataSource();
      
      try {
          String path = getClass().getClassLoader().getResource("db.properties").getPath();
 
          FileInputStream in = new FileInputStream(path);
          prop.load(in);
 
          String driver = prop.getProperty("driver");
          String url = prop.getProperty("url");
          String username = prop.getProperty("uname");
          String password = prop.getProperty("pass");
 
          ds.setDriverClassName(driver);
          ds.setUrl(url);
          ds.setUsername(username);
          ds.setPassword(password);
          in.close();
      } catch (FileNotFoundException e) {
 
      } catch (IOException e) {
 
      }
      
      return ds;
  }
 
  // JPA Hibernate
  @Bean
  public JpaVendorAdapter jpaVendorAdapter() {
     HibernateJpaVendorAdapter adapter = new HibernateJpaVendorAdapter();
     adapter.setDatabase(Database.MYSQL);
     adapter.setDatabasePlatform("org.hibernate.dialect.MySQL5InnoDBDialect");
     adapter.setShowSql(true);
     adapter.setGenerateDdl(false);
   
     return adapter;
  }
      
  @Bean
  public LocalContainerEntityManagerFactoryBean entityManagerFactory(DataSource dataSource, JpaVendorAdapter jpaVendorAdapter) {
     LocalContainerEntityManagerFactoryBean emfb = new LocalContainerEntityManagerFactoryBean();
     emfb.setDataSource(dataSource);
     emfb.setJpaVendorAdapter(jpaVendorAdapter);
     emfb.setPackagesToScan("com.lee.entity");
   
     return emfb;
  }
   
  @Bean
  pblic PlatformTransactionManager transactionManager(EntityManagerFactory entityManagerFactory) {
     return new JpaTransactionManager(entityManagerFactory);
  }
      
}

創(chuàng)建Entity，Entity需要提供getter, setter方法泉坐，用于關(guān)聯(lián)數(shù)據(jù)表中的對應(yīng)字段

@Entity                    // 聲明這個類是實體類(Entity)
@Table(name = "t_user")    // 指定關(guān)聯(lián)的數(shù)據(jù)表的名稱
public class User {
    private Long id;
    private String firstName;
    private String lastName;
 
    public User() {
        this("testFirstName", "testLastName");
    }
 
    public User(String firstName, String lastName) {
        this.firstName = firstName;
        this.lastName = lastName;
    }
 
    @Id                   // 聲明這個屬性是數(shù)據(jù)庫中的ID字段
    @GeneratedValue       // 聲明這個ID值是自增長(數(shù)據(jù)庫中 AUTO_INCREMENT)
    public Long getId() {
        return id;
    }
 
    public void setId(Long id) {
        this.id = id;
    }
 
    @Column(name = "firstName")    // 在getter方法聲明這個屬性關(guān)聯(lián)數(shù)據(jù)庫中firstName字段
    public String getFirstName() {
        return firstName;
    }
 
    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }
 
    @Column(name = "lastName")    // 在getter方法聲明這個屬性關(guān)聯(lián)數(shù)據(jù)庫中l(wèi)astName字段
    public String getLastName() {
        return lastName;
    }
 
    public void setLastName(String lastName) {
        this.lastName = lastName;
    }
 
    /*
    用于打印信息
     */
    @Override
    public String toString() {
        return new StringBuilder()
                .append("id:").append(id)
                .append(", firstName:").append(firstName)
                .append(", lastName:").append(lastName)
                .toString();
    }
}

創(chuàng)建repository

public interface UserRepository extends CrudRepository<User, Long> {
}

JUnit測試

@RunWith(SpringJUnit4ClassRunner.class)
@ContextConfiguration(classes = {DataSourceConfig.class})
@FixMethodOrder(MethodSorters.NAME_ASCENDING)
public class UserRepositoryTest {
 
    @Autowired
    private UserRepository userRepository;
    private static User user;
 
    @Test
    public void test_00_init() {
        user = new User("Lee", "Fly");
        System.out.println(user);
    }
 
    @Test
    public void test_01_save() {
        user = userRepository.save(user);
        System.out.println(user);
        assertNotNull(user.getId());
    }
 
    @Test
    public void test_02_update() {
        String rename = "ModifyName";
        user.setFirstName(rename);
        user = userRepository.save(user);
        System.out.println(user);
        assertEquals(rename, user.getFirstName());
    }
 
    @Test
    public void test_10_delete() {
        userRepository.delete(user);
        assertNull(userRepository.findOne(user.getId()));
    }
}

注意：在配置文件中使用了數(shù)據(jù)庫配置信息文件, db.properties, 沒有給出, 可以更改成自己的配置方式, 或使用下面的源碼
源碼地址: https://github.com/LeeSpringFly/learnSpringData
如果運行正常为鳄，每一個測試都會顯示綠條，表示成功