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.xsdhttp://www.springframework.org/schema/aop http://www.springframework.org/schema/aop/spring-aop.xsdhttp://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context.xsdhttp://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc.xsdhttp://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx.xsdhttp://www.springframework.org/schema/data/jpahttp://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;}@Overridepublic 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

2. 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：
#2020.1.26笔记——springdatajpa
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。
2. 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*/@Testpublic 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*/@Testpublic 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

		@Testpublic 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*/@Testpublic 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@Transactionalpublic 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

 @Testpublic 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")@Modifyingpublic void updateCustomer(Long custId,String custName);

基本讲解都在代码里。故不再赘述
5. 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*/@Testpublic 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*/@Testpublic 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：

 @Testpublic void testFindByname(){final Customer chenyameng = customerDao.findByCustName("chenyameng");System.out.println(chenyameng);}@Testpublic void testFindCuastNameLike(){final Customer chenyameng = customerDao.findByCustNameLike("chenya%");System.out.println(chenyameng);}@Testpublic 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。