概述:
? JPA是ORM框架的一个规范,而ORM框架就是不注重SQL语句,注重对象的操作,把对象和数据库进行隐射从而到达操作对象已达到操作数据库表;
例如:
? INSERT INTO *** VALUES( id , user , address )
? 大体的SQL语句不会更改,那么只要我们把需要替换的给做成映射替换成真正要执行的语句就可以了;
<?xml version="1.0" encoding="UTF-8"?>
<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.javacat7</groupId>
<artifactId>jpa-day01</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
<project.hibernate.version>5.0.7.Final</project.hibernate.version>
</properties>
<dependencies>
<!--mysql-->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>8.0.16</version>
</dependency>
<!--测试包-->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
</dependency>
<!--hibernate支持包-->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${project.hibernate.version}</version>
</dependency>
<!--c3p0连接池-->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-c3p0</artifactId>
<version>${project.hibernate.version}</version>
</dependency>
<!--日志-->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>1.2.17</version>
</dependency>
</dependencies>
</project>
<?xml version="1.0" encoding="UTF-8"?>
<persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0">
<!--需要配置persistence-unit节点
name:持久化单元名称
transaction-type:事务管理的方式(JTA:分布式事务管理,RESOURCE_LOCAL:本地事务管理)
-->
<persistence-unit name="myJpa" transaction-type="RESOURCE_LOCAL">
<!--jpa的实现方式-->
<provider>org.hibernate.jpa.HibernatePersistenceProvider</provider>
<!--可选配置-->
<propertes>
<!--数据库信息
用户名:javax.persistence.jdbc.user
密码 :javax.persistence.jdbc.password
驱动 :javax.persistence.jdbc.driver
url :javax.persistence.jdbc.url
-->
<properties>
<property name="javax.persistence.jdbc.user" value="root"/>
<property name="javax.persistence.jdbc.password" value="root"/>
<property name="javax.persistence.jdbc.driver" value="com.mysql.cj.jdbc.Driver"/>
<property name="javax.persistence.jdbc.url" value="jdbc:mysql:///test?serverTimezone=UTC"/>
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
</properties>
<!--
是否显示sql[hibernate.show_sql] (true,false)
是否对显示的sql优化[hibernate.format_sql] (true,false)
自动创建数据库[hibernate.hbm2ddl.auto] (
create[先删除在创建],
update[有就不创建],
none[不删除,没有也不创建]
)
-->
<property name="hibernate.show_sql" value="true"/>
<property name="hibernate.format_sql" value="true"/>
<property name="hibernate.hbm2ddl.auto" value="create"/>
</propertes>
</persistence-unit>
</persistence>
import javax.persistence.*;
@Entity
@Table(name = "user")
public class User {
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "user_id")
private Integer userId;
@Column(name = "user_name")
private String name;
@Column(name = "user_sex")
private String sex;
@Column(name = "user_address")
private String address;
public Integer getUserId() {return userId;}
public void setUserId(Integer userId) {this.userId = userId;}
public String getName() {return name;}
public void setName(String name) {this.name = name;}
public String getSex() {return sex;}
public void setSex(String sex) {this.sex = sex;}
public String getAddress() {return address;}
public void setAddress(String address) {this.address = address;}
}
public class TestJPA {
@Test
public void testSave(){
//实体类管理工厂
EntityManagerFactory factory = Persistence.createEntityManagerFactory("myjpa");
EntityManager em = factory.createEntityManager();//实体类
EntityTransaction tx = em.getTransaction();//事务管理器
tx.begin();//开启事务
User user = new User();
user.setName("hello");
user.setAddress("jpa");
em.persist(user);//增
em.remove(user);//删
em.merge(user);//改
User userInfo1 = em.find(User.class, 1);//立即查询
User userInfo2 = em.getReference(User.class, 1);//懒加载查询
tx.commit();//提交事务
em.close();//关闭连接
factory.close();//关闭工厂
}
}
JPQL和SQL语句不同,JQPL是查询对象,语法和SQL类似
//查询全部
String jpql = "from User ";
Query query = em.createQuery(jpql);
List resultList = query.getResultList();
//倒序排序
String jpql = "from User order by userId desc ";
Query query = em.createQuery(jpql);
List resultList = query.getResultList();
//统计查询
String sql = "select count(userId) from User ";
Query query = em.createQuery(sql);
Object singleResult = query.getSingleResult();
//分页查询
String sql = "from User ";
Query query = em.createQuery(sql);
query.setFirstResult(0);
query.setMaxResults(2);
List list = query.getResultList();
//条件查询
String sql = "from User where name = ?";
Query query = em.createQuery(sql);
query.setParameter(1,"sss");
Object singleResult = query.getSingleResult();
<properties>
<spring.version>5.0.2.RELEASE</spring.version>
<hibernate.version>5.0.7.Final</hibernate.version>
<slf4j.version>1.6.6</slf4j.version>
<log4j.version>1.2.12</log4j.version>
<c3p0.version>0.9.1.2</c3p0.version>
<mysql.version>5.1.6</mysql.version>
</properties>
<dependencies>
<!-- junit单元测试 -->
<dependency>
<groupId>junit</groupId>
<artifactId>junit</artifactId>
<version>4.12</version>
<scope>test</scope>
</dependency>
<!-- spring beg -->
<dependency>
<groupId>org.aspectj</groupId>
<artifactId>aspectjweaver</artifactId>
<version>1.6.8</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-aop</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-context-support</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- spring对orm框架的支持包-->
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-beans</artifactId>
<version>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-core</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- spring end -->
<!-- hibernate beg -->
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-core</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-entitymanager</artifactId>
<version>${hibernate.version}</version>
</dependency>
<dependency>
<groupId>org.hibernate</groupId>
<artifactId>hibernate-validator</artifactId>
<version>5.2.1.Final</version>
</dependency>
<!-- hibernate end -->
<!-- c3p0 beg -->
<dependency>
<groupId>c3p0</groupId>
<artifactId>c3p0</artifactId>
<version>${c3p0.version}</version>
</dependency>
<!-- c3p0 end -->
<!-- log end -->
<dependency>
<groupId>log4j</groupId>
<artifactId>log4j</artifactId>
<version>${log4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-api</artifactId>
<version>${slf4j.version}</version>
</dependency>
<dependency>
<groupId>org.slf4j</groupId>
<artifactId>slf4j-log4j12</artifactId>
<version>${slf4j.version}</version>
</dependency>
<!-- log end -->
<dependency>
<groupId>mysql</groupId>
<artifactId>mysql-connector-java</artifactId>
<version>${mysql.version}</version>
</dependency>
<!-- spring data jpa 的坐标-->
<dependency>
<groupId>org.springframework.data</groupId>
<artifactId>spring-data-jpa</artifactId>
<version>1.9.0.RELEASE</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-test</artifactId>
<version>${spring.version}</version>
</dependency>
<!-- el beg 使用spring data jpa 必须引入 -->
<dependency>
<groupId>javax.el</groupId>
<artifactId>javax.el-api</artifactId>
<version>2.2.4</version>
</dependency>
<dependency>
<groupId>org.glassfish.web</groupId>
<artifactId>javax.el</artifactId>
<version>2.2.4</version>
</dependency>
<!-- el end -->
</dependencies>
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:jpa="http://www.springframework.org/schema/data/jpa"
xmlns:context="http://www.springframework.org/schema/context"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd">
<context:property-placeholder location="classpath:db.properties"/>
<!-- 1.创建entityManagerFactory对象交给spring容器管理-->
<bean id="entityManagerFactoty" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<!--配置的扫描的包（实体类所在的包） -->
<property name="packagesToScan" value="com.javacat7.entity" />
<!-- jpa的实现厂家 -->
<property name="persistenceProvider">
<bean class="org.hibernate.jpa.HibernatePersistenceProvider"/>
</property>
<!--jpa的供应商适配器 -->
<property name="jpaVendorAdapter">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
<!--配置是否自动创建数据库表 -->
<property name="generateDdl" value="true" />
<!--指定数据库类型 -->
<property name="database" value="MYSQL" />
<!--数据库方言：支持的特有语法 -->
<property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
<!--是否显示sql -->
<property name="showSql" value="true" />
</bean>
</property>
<!--jpa的方言 ：高级的特性 -->
<property name="jpaDialect" >
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
</property>
</bean>
<!--2.创建数据库连接池 -->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="user" value="${jdbc.username}"></property>
<property name="password" value="${jdbc.password}"></property>
<property name="jdbcUrl" value="${jdbc.url}" ></property>
<property name="driverClass" value="${jdbc.driver}"></property>
</bean>
<!--3.整合spring dataJpa-->
<jpa:repositories base-package="com.javacat7.dao" transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactoty" ></jpa:repositories>
<!--4.配置事务管理器 -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactoty"></property>
</bean>
<!-- 5. 配置包扫描-->
<context:component-scan base-package="com.javacat7" ></context:component-scan>
</beans>
<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
xmlns:context="http://www.springframework.org/schema/context" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:aop="http://www.springframework.org/schema/aop"
xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd http://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsd">
<!--1.扫描@Service注解的包-->
<context:component-scan base-package="com.javacat7.service"/>
<!--2.Spring声明式事务-->
<!--2.1 创建事务管理器-->
<bean id="transactionManager" class="org.springframework.jdbc.datasource.DataSourceTransactionManager">
<!--注入数据源-->
<!--dataSource这里爆红，不用管它-->
<property name="dataSource" ref="dataSource"/>
</bean>
<!--2.2 创建事务通知-->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="find*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="search*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="select*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="get*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="query*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="load*" propagation="SUPPORTS" read-only="true"/>
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
<!--2.3 创建事务切面-->
<aop:config>
<!--切入点-->
<aop:pointcut id="pt" expression="execution(* com.javacat7.service.*.impl.*.*(..))"/>
<aop:advisor advice-ref="txAdvice" pointcut-ref="pt"/>
</aop:config>
</beans>
public interface UserMapper extends JpaRepository<User,Integer>, JpaSpecificationExecutor<User> {
}
<dependency>
<groupId>org.springframework.boot</groupId>
<artifactId>spring-boot-starter-data-jpa</artifactId>
</dependency>
spring:
datasource:
url: jdbc:mysql://localhost:3306/mytest
type: com.alibaba.druid.pool.DruidDataSource
username: root
password: root
driver-class-name: com.mysql.jdbc.Driver #驱动
jpa:
hibernate:
ddl-auto: update #自动更新
show-sql: true #日志中显示sql语句
@Entity
@Table(name="user")
@Data
public class User{
@Id
@GeneratedValue(strategy= GenerationType.IDENTITY)
@Column(name="user_id")
private Integer userId;
@Column(name="userName")
private String userName;
}
public interface UserMapper extends JpaRepository<User,Integer>,JpaSpecificationExecutor<User>{}
原文：https://www.cnblogs.com/javacat7/p/14758040.html