2020.1.26笔记——springdatajpa
使用jpa的步骤：
1. 导入maven坐标
<?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>org.example</groupId>
<artifactId>springDataJpa2</artifactId>
<version>1.0-SNAPSHOT</version>
<properties>
<spring.version>4.2.4.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>4.9</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>${spring.version}</version>
</dependency>
<dependency>
<groupId>org.springframework</groupId>
<artifactId>spring-orm</artifactId>
<version>${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>
<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>4.2.4.RELEASE</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>
</project>
2. 配置springdatajpa的xml文件，就是配置数据库，当项目运行的时候可以正常使用jpa
<?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:aop="http://www.springframework.org/schema/aop"
xmlns:context="http://www.springframework.org/schema/context"
xmlns:jdbc="http://www.springframework.org/schema/jdbc" xmlns:tx="http://www.springframework.org/schema/tx"
xmlns:jpa="http://www.springframework.org/schema/data/jpa" xmlns:task="http://www.springframework.org/schema/task"
xsi:schemaLocation="
http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.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
http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsd
http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsd
http://www.springframework.org/schema/data/jpa
http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
<!-- 1.dataSource 配置数据库连接池-->
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
<property name="driverClass" value="com.mysql.jdbc.Driver" />
<property name="jdbcUrl" value="jdbc:mysql://localhost:3306/springdatajpa" />
<property name="user" value="root" />
<property name="password" value="root" />
</bean>
<!-- 2.配置entityManagerFactory -->
<bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
<property name="dataSource" ref="dataSource" />
<property name="packagesToScan" value="cn.itcast.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="false" />
<!--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语句-->
<property name="showSql" value="true" />
</bean>
</property>
<!--jpa方言，高级的特性-->
<property name="jpaDialect">
<bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
</property>
</bean>
<!-- 3.事务管理器-->
<!-- JPA事务管理器 -->
<bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
<property name="entityManagerFactory" ref="entityManagerFactory" />
</bean>
<!-- 整合spring data jpa-->
<jpa:repositories base-package="cn.itcast.dao"
transaction-manager-ref="transactionManager"
entity-manager-factory-ref="entityManagerFactory"></jpa:repositories>
<!-- 4.txAdvice-->
<tx:advice id="txAdvice" transaction-manager="transactionManager">
<tx:attributes>
<tx:method name="save*" propagation="REQUIRED"/>
<tx:method name="insert*" propagation="REQUIRED"/>
<tx:method name="update*" propagation="REQUIRED"/>
<tx:method name="delete*" propagation="REQUIRED"/>
<tx:method name="get*" read-only="true"/>
<tx:method name="find*" read-only="true"/>
<tx:method name="*" propagation="REQUIRED"/>
</tx:attributes>
</tx:advice>
<!-- 5.aop-->
<aop:config>
<aop:pointcut id="pointcut" expression="execution(* cn.itcast.service.*.*(..))" />
<aop:advisor advice-ref="txAdvice" pointcut-ref="pointcut" />
</aop:config>
<context:component-scan base-package="cn.itcast"></context:component-scan>
<!--组装其它 配置文件-->
</beans>
以上的文档内都有具体的内容解释，故不再赘述；
案例：
创建客户实体类：
package cn.itcast.entity; import javax.persistence.*; /** * @Created by Intellij IDEA. * @author: 陈亚萌 * @Date: 2020/1/24 * 实体类和表的映射关系 * @Entity声明实体列 * @Table * 类中和表中字段的映射关系 * @Id * @GeneratedValue * @Column */ @Entity @Table(name = "cst_customer") public class Customer { @Id @GeneratedValue(strategy = GenerationType.IDENTITY) @Column(name = "cust_id") private Long custId; @Column(name = "cust_name") private String custName; @Column(name = "cust_source") private String custSource; @Column(name = "cust_level") private String custLevel; @Column(name = "cust_industry") private String custIndustry; @Column(name = "cust_phone") private String custPhone; @Column(name = "cust_address") private String custAddress; public Long getCustId() { return custId; } public void setCustId(Long custId) { this.custId = custId; } public String getCustAddress() { return custAddress; } public void setCustAddress(String custAddress) { this.custAddress = custAddress; } public String getCustIndustry() { return custIndustry; } public void setCustIndustry(String custIndustry) { this.custIndustry = custIndustry; } public String getCustLevel() { return custLevel; } public void setCustLevel(String custLevel) { this.custLevel = custLevel; } public String getCustName() { return custName; } public void setCustName(String custName) { this.custName = custName; } public String getCustPhone() { return custPhone; } public void setCustPhone(String custPhone) { this.custPhone = custPhone; } public String getCustSource() { return custSource; } public void setCustSource(String custSource) { this.custSource = custSource; } @Override public String toString() { return "Customer{" + "custId=" + custId + ", custAddress='" + custAddress + '\'' + ", custIndustry='" + custIndustry + '\'' + ", custLevel='" + custLevel + '\'' + ", custName='" + custName + '\'' + ", custPhone='" + custPhone + '\'' + ", custSource='" + custSource + '\'' + '}'; } }
一般来说，注解@Column(name = "cust_id")一般不用加，他会自动根据你的名字来路由表结构的。如果不想写getset方法可以使用lombok中的@Data注解，省去写toString方法和setget方法的时间
创建接口类CustomerDao,必须继承JpaRepository<Customer,Long>, JpaSpecificationExecutor
，其中 *1. JpaRepository<操作的实体类类型,实体类中主键属性的类型> *2. JpaSpecificationExecutor<操作的实体类型>
根据测试类进行测试增删改查：
####一、jpa自己封装的方法：测试类的写法，一般在创建Maven项目后，会有test包，然后根据你需要测试的方法来写包，包结构必须一一对应：
另外，在测试类的上面需要加上注释：//声明spring提供的单元测试 @RunWith(SpringJUnit4ClassRunner.class) //指定spring容器的配置信息 @ContextConfiguration(locations = "classpath:applicationContext.xml")测试查找，根据id查找：
@Test /** * 根据id查询 */ public void testFindOne(){ final Customer one = customerDao.findOne(2L); System.out.println(one); }test注解必须加上，如果不加会报错。这种是根据jpa自动封装的方法进行查找出来的结果。测试保存或者更新
/** * 保存或者更新 * 根据传递的对象是否有存在主键id，如果没有主键id，则保存 * 如果传递的对象存在主键的属性id，则更新数据 */ @Test public void saveOne(){ Customer customer=new Customer(); customer.setCustName("chenyameng111"); customer.setCustLevel("vip"); customer.setCustIndustry("jiaoyu"); final Customer save = customerDao.save(customer); System.out.println(save); } @Test /** * 更新按照id */ public void updateOne(){ Customer customer=new Customer(); customer.setCustId(3L); customer.setCustName("陈亚萌111"); customerDao.save(customer); }
保存和更新有区别，因为主键设置为自增，所以保存的时候不需要传递id，但是如果你要更新数据的时候，需要进行传递id
3. 删除略
4. 查找所有：
/**
* 查询所有
*/
@Test
public void findAll(){
final List<Customer> all = customerDao.findAll();
for (Customer customer : all) {
System.out.println(customer);
}
}
查找所有也是使用封装好的方法
5. 查询总数
@Test
public void testCount(){
//查询客户数量
final long count = customerDao.count();
System.out.println(count);
}
6. 判断该条数据是否存在，一般为主键来判断
/**
* 判断id是否存在
* 可以查询id为4
* 的用户，如果值为空则不存在
*
* 2. 判断数据库中id为4的数量，为0则不存在 若》0
*/
@Test
public void testExists(){
final boolean exists = customerDao.exists(4l);
System.out.println(exists);
}
7. findOne getOne的区别
/**
* 根据id从数据库中查询
* @Transactional:保证getOne正常运行，事务处理
* findOne: em.find();立即加载
* getOne: em.getReference()：延迟加载 返回是客户的动态代理对象，什么时候用什么时候查询
*/
@Test
@Transactional
public void testGetOne(){
final Customer one = customerDao.getOne(4L);
System.out.println(one);
}
二、jpql方法<如果想自定义sql语句>：
jpql的存在主要就是为了是jpa更加灵活，比如可以完成模糊查询，按照指定位置更新数据，查询所有等
根据姓名查找
@Test /** * 根据id查询 */ public void testFindJpql(){ final Customer one = customerDao.findJpq("chenyameng"); System.out.println(one); }在CustomerDao中的定义为：
/** * 根据客户名称查询客户 * 使用jpql的形式 * jpql：from Customer where custName = ? * 配置jpql语句： * @Query */ @Query(value = "from Customer where custName = ?") public Customer findJpq(String custName);根据id和用户名查找
@Test public void testFindCustNameAndId(){ final Customer chenyameng = customerDao.findCustNameAndId("chenyameng", 2L); System.out.println(chenyameng); }在CustomerDao中的定义：
/** * 根据客户名称和客户id查询 * jpql：from Customer where custName=? and custId=? * 对于多个占位符参数： * 赋值的时候，默认的情况下，占位符的位置需要和方法参数中的位置保持一致 * 对于指定占位符参数的位置： * ？ 索引的方式指定此占位的取值来源 */ @Query(value = "from Customer where custName=? and custId=?") public Customer findCustNameAndId(String custName,Long custId);- 更新
/** * 测试jpql的更新 * springdatajpa使用jpql完成更新或者删除操作 * 1. 需要手动添加事务的支持 * 2. 默认执行结束后，回滚事务 * @Rollback(value = false)不会滚 */ @Test @Transactional @Rollback(value = false) public void testUpdataCustomer(){ customerDao.updateCustomer(4L,"111222"); }CustomerDao：
/** * 使用jpql完成更新操作 * 案例： 根据id更新，客户的名称 * 更新4号客户的名称，将名称改为111222 * sql：update cst_customer set cust_name= ? where cust_id =? * jpql: update Customer set custName = ? where custId=? * @Query:代表的是进行查询 * 声明此方法是进行更新操作 * @Modifying：更新操作 */ @Query(value = "update Customer set custName = ?2 where custId=?1") @Modifying public void updateCustomer(Long custId,String custName);
基本讲解都在代码里。故不再赘述查找所有 使用mysql或者sql的语法进行查找的时候需要加上nativeQuery=true
/** * 测试sql查询 */ @Test public void testListAll(){ final List<Object[]> sql = customerDao.findSql(); for (Object[] objects : sql) { System.out.println(Arrays.toString(objects)); } }CustomerDao：
/** * 使用sql形式查询 * 查询全部的客户 * sql:select * from customer * @Query:配置sql查询 * value：sql语句 * nativeQuery表示是否使用本地查询 true sql false：jpql */ @Query(value = "select * from cst_customer",nativeQuery = true) public List<Object [] > findSql();使用sql语句进行模糊查询：
/** * 测试sql模糊查询 */ @Test public void testCondition(){ final List<Object[]> sql = customerDao.findByCondition("chenyam%"); for (Object[] objects : sql) { System.out.println(Arrays.toString(objects)); } }CustomerDao：
@Query(value = "select * from cst_customer where cust_name like ?1",nativeQuery = true) List<Object [] > findByCondition(String name);
根据jpa封装好的方法进行查询：
@Test public void testFindByname(){ final Customer chenyameng = customerDao.findByCustName("chenyameng"); System.out.println(chenyameng); } @Test public void testFindCuastNameLike(){ final Customer chenyameng = customerDao.findByCustNameLike("chenya%"); System.out.println(chenyameng); } @Test public void testFindCustNameLikeAndIndustry(){ final List<Customer> customer = customerDao.findByCustNameLikeAndCustIndustry("陈亚萌%", "教育"); for (Customer customer1 : customer) { System.out.println(customer1); } }
CustomerDao：
/**
* 方法名约定：
* findBy:查询
* 对象中的属性名称，需要首字母大写：查询的条件
* CustName：
* * 默认情况下使用的方式查询
* 模糊匹配查询：
* 1. findBy+属性名称（根据属性名称完成匹配的查询）
* 2. findBy+属性名称+“查询方式”（Like|isnull）
* findByCustNameLike 可以进行模糊查询
* 3. 多条件查询
* findBy+属性名+“查询方式” + “多条件的连接符And | Or（select * from c where sss）”+属性名+ “查询方式”
* findByCustName:根据客户名称查询
* 在springdatajpa的运行阶段：会根据方法名称进行解析，findBy from xxx
* 属性名称 where 。。。
*/
Customer findByCustName(String custName);
Customer findByCustNameLike(String name);
/**
* 使用客户名模糊匹配和客户所属行业精准匹配的查询
*
*/
List<Customer> findByCustNameLikeAndCustIndustry(String name,String industry);
待总结：
- 项目内容的全部整理。
- jpa最后一部分，分页等内容的总结。
来源：https://www.cnblogs.com/chenyameng/p/12235190.html