SpringBoot集成Hibernate

Hibernate是什么？

Hibernate与MyBatis都是流行的持久层开发框架，只不过Hibernate是全自动ORM框架，不需要关心sql编写。

Hibernate 是一个高性能的对象/关系映射（ORM）持久化存储和查询的服务，不仅负责从Java类到数据库表的映射（还包括从Java数据类型到SQL数据类型的映射），还提供了面向对象的数据查询检索机制，从而极大地缩短了手动处理SQL和JDBC上的开发时间。同时，Hibernate还实现了JPA规范，在SpringBoot中，JPA的默认实现就是使用的Hibernate。

JPA和Hibernate？

JPA

JPA(Java Persistence API)是Sun官方提出的Java持久化规范，它为Java开发人员提供了一种对象/关系映射工具来管理Java应用中的关系数据。

可以通过注解或者XML描述【对象-关系表】之间的映射关系，并将实体对象持久化到数据库中。

JPA仅仅是一种规范，也就是说JPA仅仅定义了一些接口，而接口是需要实现才能工作的。所以底层需要某种实现，而Hibernate就是实现了JPA接口的ORM框架。

Hibernate

Hibernate是一个开放源代码的对象关系映射框架，它对JDBC进行了非常轻量级的对象封装，它将POJO与数据库表建立映射关系，是一个全自动的ORM框架。 Hibernate可以自动生成SQL语句、自动执行，从而使得Java程序员可以随心所欲的使用对象编程思维来操纵数据库。

实际上，JPA规范制定过程中就是借鉴了Hibernate等这些开源的持久框架，也就是说Hibernate的出现比JPA还要早些。

在Hibernate中使用的注解就是JPA注解，Hibernate实现了JPA规范。

Spring Data JPA

spirng data jpa是spring提供的一套简化JPA开发的框架，按照约定好的【方法命名规则】写dao层接口，就可以在不写接口实现的情况下，实现对数据库的访问和操作。同时提供了很多除了CRUD之外的功能，如分页、排序、复杂查询等等。

Spring Data JPA 可以理解为 JPA 规范的再次封装抽象，底层还是使用了 Hibernate 的 JPA 技术实现。

SpringData

Spring Data 是持久层通用解决方案，支持关系型数据库 Oracle、MySQL、非关系型数据库NoSQL、Map-Reduce 框架、云基础数据服务、搜索服务。

Spring Data是一个开源框架而Spring Data JPA是这个框架的模块。

一、新建SpringBoot项目

在pom.xml中引入maven依赖

        <dependency><groupId>org.springframework.boot</groupId><artifactId>spring-boot-starter-data-jpa</artifactId></dependency><dependency><groupId>mysql</groupId><artifactId>mysql-connector-java</artifactId><version>8.0.17</version><scope>runtime</scope></dependency><dependency><groupId>com.alibaba</groupId><artifactId>druid</artifactId><version>1.1.2</version></dependency><dependency><groupId>org.projectlombok</groupId><artifactId>lombok</artifactId><version>1.18.10</version></dependency>

创建数据库

create table books
(book_id int(5) primary key auto_increment,title varchar(200),category varchar(100)
)
INSERT INTO `books` (`book_id`, `title`, `category`) VALUES(1, '123', 'qwe'),(2, '456', 'asd'),(3, '789', 'zxc');

配置文件application.yml

spring:jpa:properties:hibernate:dialect: org.hibernate.dialect.MySQLDialectnew_generator_mappings: falseformat_sql: truedatasource:url: jdbc:mysql://localhost:3306/ss?serverTimezone=UTC&useSSL=false&autoReconnect=true&tinyInt1isBit=false&useUnicode=true&characterEncoding=utf8username: rootpassword: 123qwe

创建如图以下包

在config下编写数据源配置

@Configuration
@EnableTransactionManagement(order = 2)
public class DataSourceConfig {@Resourceprivate DruidProperties druidProperties;/*** 单数据源连接池配置*/@Beanpublic DruidDataSource singleDatasource() {DruidDataSource dataSource = new DruidDataSource();druidProperties.config(dataSource);return dataSource;}
}

@Component
@ConfigurationProperties(prefix = "spring.datasource")
public class DruidProperties {private String url;private String username;private String password;private String driverClassName = "com.mysql.cj.jdbc.Driver";private Integer initialSize = 10;private Integer minIdle = 3;private Integer maxActive = 60;private Integer maxWait = 60000;private Boolean removeAbandoned = true;private Integer removeAbandonedTimeout = 180;private Integer timeBetweenEvictionRunsMillis = 60000;private Integer minEvictableIdleTimeMillis = 300000;private String validationQuery = "SELECT 'x'";private Boolean testWhileIdle = true;private Boolean testOnBorrow = false;private Boolean testOnReturn = false;private Boolean poolPreparedStatements = true;private Integer maxPoolPreparedStatementPerConnectionSize = 50;private String filters = "stat";public void config(DruidDataSource dataSource) {dataSource.setDbType(JdbcConstants.MYSQL);dataSource.setUrl(url);dataSource.setUsername(username);dataSource.setPassword(password);dataSource.setDriverClassName(driverClassName);// 定义初始连接数dataSource.setInitialSize(initialSize);// 最小空闲dataSource.setMinIdle(minIdle);// 定义最大连接数dataSource.setMaxActive(maxActive);// 获取连接等待超时的时间dataSource.setMaxWait(maxWait);// 超过时间限制是否回收dataSource.setRemoveAbandoned(removeAbandoned);// 超过时间限制多长dataSource.setRemoveAbandonedTimeout(removeAbandonedTimeout);// 配置间隔多久才进行一次检测，检测需要关闭的空闲连接，单位是毫秒dataSource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);// 配置一个连接在池中最小生存的时间，单位是毫秒dataSource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);// 用来检测连接是否有效的sql，要求是一个查询语句dataSource.setValidationQuery(validationQuery);// 申请连接的时候检测dataSource.setTestWhileIdle(testWhileIdle);// 申请连接时执行validationQuery检测连接是否有效，配置为true会降低性能dataSource.setTestOnBorrow(testOnBorrow);// 归还连接时执行validationQuery检测连接是否有效，配置为true会降低性能dataSource.setTestOnReturn(testOnReturn);// 打开PSCache，并且指定每个连接上PSCache的大小dataSource.setPoolPreparedStatements(poolPreparedStatements);dataSource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);// 属性类型是字符串，通过别名的方式配置扩展插件，常用的插件有：// 监控统计用的filter:stat// 日志用的filter:log4j// 防御SQL注入的filter:walltry {dataSource.setFilters(filters);} catch (SQLException e) {e.printStackTrace();}}public String getUrl() {return url;}public void setUrl(String url) {this.url = url;}public String getUsername() {return username;}public void setUsername(String username) {this.username = username;}public String getPassword() {return password;}public void setPassword(String password) {this.password = password;}public String getDriverClassName() {return driverClassName;}public void setDriverClassName(String driverClassName) {this.driverClassName = driverClassName;}public Integer getInitialSize() {return initialSize;}public void setInitialSize(Integer initialSize) {this.initialSize = initialSize;}public Integer getMinIdle() {return minIdle;}public void setMinIdle(Integer minIdle) {this.minIdle = minIdle;}public Integer getMaxActive() {return maxActive;}public void setMaxActive(Integer maxActive) {this.maxActive = maxActive;}public Integer getMaxWait() {return maxWait;}public void setMaxWait(Integer maxWait) {this.maxWait = maxWait;}public Integer getTimeBetweenEvictionRunsMillis() {return timeBetweenEvictionRunsMillis;}public void setTimeBetweenEvictionRunsMillis(Integer timeBetweenEvictionRunsMillis) {this.timeBetweenEvictionRunsMillis = timeBetweenEvictionRunsMillis;}public Integer getMinEvictableIdleTimeMillis() {return minEvictableIdleTimeMillis;}public void setMinEvictableIdleTimeMillis(Integer minEvictableIdleTimeMillis) {this.minEvictableIdleTimeMillis = minEvictableIdleTimeMillis;}public String getValidationQuery() {return validationQuery;}public void setValidationQuery(String validationQuery) {this.validationQuery = validationQuery;}public Boolean getTestWhileIdle() {return testWhileIdle;}public void setTestWhileIdle(Boolean testWhileIdle) {this.testWhileIdle = testWhileIdle;}public Boolean getTestOnBorrow() {return testOnBorrow;}public void setTestOnBorrow(Boolean testOnBorrow) {this.testOnBorrow = testOnBorrow;}public Boolean getTestOnReturn() {return testOnReturn;}public void setTestOnReturn(Boolean testOnReturn) {this.testOnReturn = testOnReturn;}public Boolean getPoolPreparedStatements() {return poolPreparedStatements;}public void setPoolPreparedStatements(Boolean poolPreparedStatements) {this.poolPreparedStatements = poolPreparedStatements;}public Integer getMaxPoolPreparedStatementPerConnectionSize() {return maxPoolPreparedStatementPerConnectionSize;}public void setMaxPoolPreparedStatementPerConnectionSize(Integer maxPoolPreparedStatementPerConnectionSize) {this.maxPoolPreparedStatementPerConnectionSize = maxPoolPreparedStatementPerConnectionSize;}public String getFilters() {return filters;}public void setFilters(String filters) {this.filters = filters;}public Boolean getRemoveAbandoned() {return removeAbandoned;}public void setRemoveAbandoned(Boolean removeAbandoned) {this.removeAbandoned = removeAbandoned;}public Integer getRemoveAbandonedTimeout() {return removeAbandonedTimeout;}public void setRemoveAbandonedTimeout(Integer removeAbandonedTimeout) {this.removeAbandonedTimeout = removeAbandonedTimeout;}
}

在entity下创建实体类

@Entity
@Table(name = "books")
@Data
public class Book implements Serializable {private static final long serialVersionUID = 1L;@Id@GeneratedValue(strategy = GenerationType.AUTO)@Column(name = "book_id")private int bookId;@Column(name = "title")private String title;@Column(name = "category")private String category;
}

创建在repository下创建Dao层接口和在impl下创建Dao实现类

public interface BookDao {List<Book> getAllBooks();Book getBookById(int bookId);void addBook(Book book);void updateBook(Book book);void deleteBook(int bookId);boolean bookExists(String title,String category);
}

@Repository
public class IBookDao implements BookDao {@PersistenceContextprivate EntityManager entityManager;@Overridepublic List<Book> getAllBooks() {String sql = "FROM Book as book ORDER BY book.bookId";return (List<Book>)entityManager.createQuery(sql).getResultList();}@Overridepublic Book getBookById(int bookId) {return entityManager.find(Book.class,bookId);}@Overridepublic void addBook(Book book) {entityManager.persist(book);}@Overridepublic void updateBook(Book book) {Book book1 = getBookById(book.getBookId());book1.setTitle(book.getTitle());book1.setCategory(book.getCategory());entityManager.flush();entityManager.clear();}@Overridepublic void deleteBook(int bookId) {entityManager.remove(getBookById(bookId));}@Overridepublic boolean bookExists(String title, String category) {String sql = "FROM Book as book WHERE book.title=?0 and book.category=?1";int count = entityManager.createQuery(sql).setParameter(0,title).setParameter(1,category).getResultList().size();return count > 0;}
}

创建业务层Service,注入BookDao

@Service
public class BookService {@Autowiredprivate BookDao bookDao;public Book getBookById(int bookId){Book book= bookDao.getBookById(bookId);return book;}public List<Book> getAllBooks(){return bookDao.getAllBooks();}public synchronized boolean addBook(Book book){if(bookDao.bookExists(book.getTitle(),book.getCategory())){return false;}else {bookDao.addBook(book);return true;}}public void updateBook(Book book){bookDao.updateBook(book);}public void deleteBook(int bookId){bookDao.deleteBook(bookId);}
}

测试类编写测试代码

再上图中测试类下编写以下代码

@RunWith(SpringRunner.class)
@SpringBootTest
@Transactional
public class HibernateApplicationTests {@Autowiredprivate BookService bookService;@Test@Rollback(false)public void contextLoads() {Book book = bookService.getBookById(1);assertThat(book.getTitle(),is("123"));List<Book> list = bookService.getAllBooks();assertThat(list,notNullValue());assertThat(list.size(), is(3));boolean flag = bookService.addBook(book);assertThat(flag, is(false));book.setTitle("012");bookService.updateBook(book);Book book1 = bookService.getBookById(1);System.out.println(book1);assertThat(book1.getTitle(), is("012"));bookService.deleteBook(1);Book article2 = bookService.getBookById(1);assertThat(article2, nullValue());}}

依次执行上面测试代码中的增删改查。根据数据库和控制台输出查看结果是否测试通过。简单的集成Hibernate已经完成。更多可以了解JPA复杂语句查询以及根据实体类自动创建数据库。