Spring Data JPA入门
Posted 雪山上的蒲公英
tags:
篇首语:本文由小常识网(cha138.com)小编为大家整理,主要介绍了Spring Data JPA入门相关的知识,希望对你有一定的参考价值。
1. Spring Data JPA是什么
它是Spring基于ORM框架、JPA规范封装的一套JPA应用框架,可使开发者用极简的代码即可实现对数据的访问和操作。它提供了包括增删改查等在内的常用功能,且易于扩展。学习并使用Spring Data JPA可以极大提高开发效率。
2. Spring Data JPA 有什么
主要看看Spring Data JPA 提供的编程接口
- Repository:最顶层的接口,是一个空接口,目的是为了统一所有的Repository的类型,且能让组件扫描时自动识别。
- CrudRepository: Repository的子接口,提供CRUD的功能。
- PagingAndSortingRepository: CrudRepository的子接口, 添加分页排序。
- JpaRepository: PagingAndSortingRepository的子接口,增加批量操作等。
- JpaSpecificationExecutor: 用来做复杂查询的接口。
接口继承关系图
3. 利用Spring Data JPA建立简单的用户管理项目
3.1 搭建项目
3.1.1 数据库建表
3.1.2 用户管理工程包结构
- com.zang.usermanage.repository (存放自定义的数据操作接口)
- com.zang.usermanage.model(存放实体模型)
- com.zang.usermanage.service(存放服务层的接口和实现)
- com.zang.usermanage.controller (如果是MVC项目可建立此包,存放控制器)
- com.zang.usermanage.exception(存放异常类)
- com.zang.usermanage.test(存放测试类)
3.1.3 所有需要的jar包
- Spring 基础jar包(版本:4.1.5)
- Spring Data Commons jar包(版本:1.9.2)
- Spring Data JPA jar包(版本:1.7.2)
- Hibernate 相关 jar包(版本:4.2.0)
- mysql数据库连接包 (版本:5.1.21)
- 日志相关jar包
- 其它jar包
3.1.4 配置与编码
创建配置
配置文件一:applicationContext.xml(Spring上下文)
<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:jdbc="http://www.springframework.org/schema/jdbc" xmlns:jee="http://www.springframework.org/schema/jee" xmlns:tx="http://www.springframework.org/schema/tx" xmlns:jpa="http://www.springframework.org/schema/data/jpa" xsi:schemaLocation=" http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-3.2.xsd http://www.springframework.org/schema/context http://www.springframework.org/schema/context/spring-context-3.2.xsd http://www.springframework.org/schema/jdbc http://www.springframework.org/schema/jdbc/spring-jdbc-3.2.xsd http://www.springframework.org/schema/jee http://www.springframework.org/schema/jee/spring-jee-3.2.xsd http://www.springframework.org/schema/tx http://www.springframework.org/schema/tx/spring-tx-3.2.xsd http://www.springframework.org/schema/data/jpa http://www.springframework.org/schema/data/jpa/spring-jpa.xsd" default-lazy-init="true"> <!--第一步--> <!--定义服务层代码存放的包扫描路径--> <context:component-scan base-package="com.zang.usermanage.service" /> <!--第二步--> <!--定义实体的工厂bean--> <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean"> <property name="persistenceUnitName" value="userPU" /> <property name="persistenceXmlLocation" value="classpath:persistence.xml"></property> </bean> <!--第三步--> <!--定义事务管理器--> <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager"> <property name="entityManagerFactory" ref="entityManagerFactory"/> </bean> <!--第四步--> <!--定义repository接口的存放目录--> <!--定义接口实现的后缀,通常用Impl--> <!--定义实体工厂的引用--> <!--定义事务管理器的引用--> <jpa:repositories base-package="com.zang.usermanage.repository" repository-impl-postfix="Impl" entity-manager-factory-ref="entityManagerFactory" transaction-manager-ref="transactionManager"/> <!--第五步--> <!--声明采用注解的方式申明事务--> <tx:annotation-driven transaction-manager="transactionManager"/> </beans>
配置文件二:persistence.xml(管理持久化)
<?xml version="1.0" encoding="UTF-8"?> <persistence xmlns="http://java.sun.com/xml/ns/persistence" version="2.0"> <persistence-unit name="userPU" transaction-type="RESOURCE_LOCAL"> <!--jpa的提供者--> <provider>org.hibernate.ejb.HibernatePersistence</provider> <properties> <!--声明数据库连接的驱动--> <property name="hibernate.connection.driver_class" value="com.mysql.jdbc.Driver"/> <!--jdbc数据库的连接地址--> <property name="hibernate.connection.url" value="jdbc:mysql://localhost:3306/user_manage"/> <property name="hibernate.connection.username" value="root"/> <property name="hibernate.connection.password" value="123"/> <!--配置方言--> <property name="hibernate.dialect" value="org.hibernate.dialect.MySQL5Dialect"/> <!--激活查询日志功能--> <property name="hibernate.show_sql" value="true"/> <!--优雅地输出Sql--> <property name="hibernate.format_sql" value="true"/> <!--添加一条解释型标注--> <property name="hibernate.use_sql_comments" value="false"/> <!--配置如何根据java模型生成数据库表结构,常用update,validate--> <property name="hibernate.hbm2ddl.auto" value="update"/> </properties> </persistence-unit> </persistence>
创建类文件并编码
User.java(用户实体类),UserRepository.java(用户的数据接口,继承JpaRepository接口), UserService.java(用户服务接口),UserServiceImpl.java(接口实现), UserNotFound.java(异常类,在查询实体未找到时抛出)
类之间关系
User.java(用户实体类)
package com.zang.usermanage.model; import javax.persistence.Entity; import javax.persistence.GeneratedValue; import javax.persistence.Id; import javax.persistence.Table; /* 实体中常用的注解: @Entity :声明这个类是一个实体类 @Table:指定映射到数据库的表格 @Id :映射到数据库表的主键属性,一个实体只能有一个属性被映射为主键 @GeneratedValue:主键的生成策略 */ @Entity @Table(name="user") public class User { @Id @GeneratedValue private Integer id; private String name; private String address; private String phone; public Integer getId() { return id; } public void setId(Integer id) { this.id = id; } public String getName() { return name; } public void setName(String name) { this.name = name; } public String getAddress() { return address; } public void setAddress(String address) { this.address = address; } public String getPhone() { return phone; } public void setPhone(String phone) { this.phone = phone; } }
UserRepository.java(用户的数据接口)
package com.zang.usermanage.repository; import org.springframework.data.jpa.repository.JpaRepository; import com.zang.usermanage.model.User; public interface UserRepository extends JpaRepository<User,Integer> { }
3.2 实现简单的增、删、改、查
JpaRepository接口方法:
- delete删除或批量删除
- findAll查找所有
- findOne查找单个
- save保存单个或批量保存
- saveAndFlush保存并刷新到数据库
接口源码如下:(实现类为org.springframework.data.jpa.repository.support.SimpleJpaRepository.class)
package org.springframework.data.jpa.repository; import java.io.Serializable; import java.util.List; import org.springframework.data.domain.Sort; import org.springframework.data.repository.NoRepositoryBean; import org.springframework.data.repository.PagingAndSortingRepository; @NoRepositoryBean public abstract interface JpaRepository<T, ID extends Serializable> extends PagingAndSortingRepository<T, ID> { public abstract List<T> findAll(); public abstract List<T> findAll(Sort paramSort); public abstract List<T> findAll(Iterable<ID> paramIterable); public abstract <S extends T> List<S> save(Iterable<S> paramIterable); public abstract void flush(); public abstract <S extends T> S saveAndFlush(S paramS); public abstract void deleteInBatch(Iterable<T> paramIterable); public abstract void deleteAllInBatch(); public abstract T getOne(ID paramID); }
3.2.1 编码实现
UserService.java(用户服务接口)
package com.zang.usermanage.service; import java.util.List;import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; public interface UserService { //添加用户 public void addUser(User user); //修改用户 public User updateUser(User user) throws UserNotFound; //删除用户,根据用户编号删除 public User deleteUser(int id) throws UserNotFound; //查询单个用户 public User getUser(int id); //查询所有用户 public List<User> getUsers(); }
UserServiceImpl.java(接口实现)
package com.zang.usermanage.service; import java.util.ArrayList; import java.util.List; import org.springframework.beans.factory.annotation.Autowired;import org.springframework.stereotype.Service; import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; import com.zang.usermanage.repository.UserRepository; @Service("userService") public class UserServiceImpl implements UserService { //自动装配 @Autowired private UserRepository userRepository; //增加用户调用save方法 @Override public void addUser(User user) { userRepository.save(user); } //更新用户先进行非空判断,再对新用户各个属性进行非空判断并赋值,最后调用save方法 //自定义异常类 UserNotFound @Override public User updateUser(User user) throws UserNotFound { User userUpdate = userRepository.findOne(user.getId()); if (userUpdate==null) throw new UserNotFound(); if (user.getName()!=null) userUpdate.setName(user.getName()); if (user.getAddress()!=null) userUpdate.setAddress(user.getAddress()); if (user.getPhone()!=null) userUpdate.setPhone(user.getPhone()); userRepository.save(userUpdate); return userUpdate; } //删除用户先进行非空判断,最后调用delete方法 @Override public User deleteUser(int id) throws UserNotFound { User userDelete = userRepository.findOne(id); if (userDelete==null) throw new UserNotFound(); userRepository.delete(userDelete); return userDelete; } //查询单个,调用findOne方法 @Override public User getUser(int id) { return userRepository.findOne(id); } //查询所有,调用findAll方法 @Override public List<User> getUsers() { return userRepository.findAll(); } }
3.2.2 测试
Client.java(测试类)
package com.zang.usermanage.test; import java.util.List; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.data.domain.Page; import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; import com.zang.usermanage.service.UserService; public class Client { public static void printUser(User user){ StringBuilder sb = new StringBuilder(); sb.append("id="+user.getId()); sb.append("name="+user.getName()); sb.append("address="+user.getAddress()); sb.append("phone="+user.getPhone()); System.out.println(sb.toString()); } public static void testList(UserService userService){ List<User> users = userService.getUsers(); if (users!=null){ for (int i=0; i<users.size();i++){ printUser(users.get(i)); } } } public static void testUpate(UserService userService) throws UserNotFound{ User user = new User(); user.setId(1); user.setAddress("北京路121号"); userService.updateUser(user); testList(userService); } public static void testAdd(UserService userService){ User user = new User(); user.setAddress("天河路120号"); user.setName("小徐"); user.setPhone("130000000"); userService.addUser(user); testList(userService); } public static void testDelete(UserService userService) throws UserNotFound{ userService.deleteUser(7); testList(userService); } public static void main(String[] arg) throws UserNotFound{ ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml"); UserService userService = (UserService) ac.getBean("userService"); //testList(userService); testUpate(userService); //testAdd(userService); //testDelete(userService); } }
3.3 实现复杂查询
3.3.1 基于方法名解析的概念
JpaRepository支持接口规范方法名查询。意思是如果在接口中定义的查询方法符合它的命名规则,就可以不用写实现。
例如:findByName这个方法表示从数据库中查询Name这个属性等于XXX的所有记录,类似于SQL语句:select * from xxTable where name=xxx这种形式
这段话有两个重点:
- 方法名需要在接口中设定
- 必须符合一定的命名规范
3.3.2 方法名构造方法
find+全局修饰+By+实体的属性名称+限定词+连接词+ ...(其它实体属性)+OrderBy+排序属性+排序方向 例如:findDistinctByFirstNameIgnoreCaseAndLastNameOrderByAgeDesc(String firstName,String lastName){......}
其中:Distinct是全局修饰(非必须),FirstName和LastName是实体的属性名,And是连接词,IgnoreCase是限定词,Age是排序属性,Desc是排序方向,限定词和连接词统称为“关键词”。
3.3.3 目前支持的关键词
常用词如下:
- 全局修饰:Distinct,Top,First
- 关键词:IsNull,IsNotNull,Like,NotLike,Containing,In,NotIn,IgnoreCase,Between,Equals,LessThan,GreaterThan,After,Before...
- 排序方向:Asc,Desc
- 连接词:And,Or
更多关键词请查看官方在线文档: https://docs.spring.io/spring-data/jpa/docs/2.0.4.RELEASE/reference/html/
3.3.4 嵌套实体方法命名规则
构词法:主实体中子实体的名称+ _ +子实体的属性名称
例如:List<Person> findByAddress_ZipCode(ZipCode zipCode) 表示查询所有 Address(地址)的zipCode(邮编)为指定值的所有Person(人员)
3.3.5 代码展示条件查询、分页、排序
UserRepository接口定义查询方法
package com.zang.usermanage.repository; import java.util.List; import org.springframework.data.domain.Sort; import org.springframework.data.domain.Page; import org.springframework.data.domain.Pageable; import org.springframework.data.jpa.repository.JpaRepository; import com.zang.usermanage.model.User; public interface UserRepository extends JpaRepository<User,Integer> { //查询需求: 从数据库中查询电话号码(phone)以指定字符串开始(例如:136)的,并且地址(address)中包含指定字符串(例如:路)的记录 提取前两条,降序排列 //select * from user where phone like \'136%\' and address like \'%路%\' order by phone desc limit 0,2 List<User> findTop2ByPhoneStartingWithAndAddressContainingOrderByPhoneDesc(String phone,String address); List<User> findTop2ByPhoneStartingWithAndAddressContaining(String phone,String address,Sort sort); //分页要用到Pageable接口 Page<User> findByPhoneStartingWithAndAddressContaining(String phone,String address,Pageable pageable); }
UserService.java
package com.zang.usermanage.service; import java.util.List; import org.springframework.data.domain.Page; import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; public interface UserService { //不分页带条件查询 public List<User> getUsersByConditionNoPage(String phone,String address); //带分页条件查询(需要得到用户列表并且得到分页信息) public Page<User> getUsersByConditionWithPage(String phone,String address,Integer page,Integer pageSize); //带分页条件查询(得到用户列表) //public List<User> getUsersByCondition(String phone,String address,Integer page,Integer pageSize); }
UserServiceImpl.java
package com.zang.usermanage.service; import java.util.ArrayList; import java.util.List; import org.springframework.beans.factory.annotation.Autowired; import org.springframework.data.domain.Page; import org.springframework.data.domain.PageRequest; import org.springframework.data.domain.Sort; import org.springframework.data.domain.Sort.Direction; import org.springframework.data.domain.Sort.Order; import org.springframework.stereotype.Service; import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; import com.zang.usermanage.repository.UserRepository; @Service("userService") public class UserServiceImpl implements UserService { //自动装配 @Autowired private UserRepository userRepository; @Override public Page<User> getUsersByConditionWithPage(String phone,String address,Integer page,Integer pageSize) { //不排序 Page<User> userPage = userRepository.findByPhoneStartingWithAndAddressContaining(phone,address,new PageRequest(page, pageSize)); //排序(三种方法) //第一种排序方式 //Page<User> userPage = userRepository.findByPhoneStartingWithAndAddressContaining(phone,address,new PageRequest(page, pageSize,new Sort(Direction.ASC,"name","phone"))); //第二种排序方式 //Order order = new Order(Direction.ASC,"phone"); //Page<User> userPage = userRepository.findByPhoneStartingWithAndAddressContaining(phone,address,new PageRequest(page, pageSize,new Sort(order)); //第三种排序方式 //List<Order> orders = new ArrayList<Order>(); //orders.add(new Order(Direction.DESC,"name")); //orders.add(new Order(Direction.ASC,"phone")); //Page<User> userPage = userRepository.findByPhoneStartingWithAndAddressContaining(phone,address,new PageRequest(page, pageSize,new Sort(orders)); return userPage; } /** * 不分页 */ @Override public List<User> getUsersByConditionNoPage(String phone,String address) { return userRepository.findTop2ByPhoneStartingWithAndAddressContainingOrderByPhoneDesc(phone, address); //return userRepository.findTop2ByPhoneStartingWithAndAddressContaining(phone, address, new Sort(Direction.ASC,"phone")); //Order order = new Order(Direction.ASC,"phone"); //return userRepository.findTop2ByPhoneStartingWithAndAddressContaining(phone, address, new Sort(order)); //List<Order> orders = new ArrayList<Order>(); //orders.add(new Order(Direction.DESC,"name")); //orders.add(new Order(Direction.ASC,"phone")); //return userRepository.findTop2ByPhoneStartingWithAndAddressContaining(phone, address, new Sort(orders); } }
Client.java(测试类)
package com.zang.usermanage.test; import java.util.List; import org.springframework.context.ApplicationContext; import org.springframework.context.support.ClassPathXmlApplicationContext; import org.springframework.data.domain.Page; import com.zang.usermanage.exception.UserNotFound; import com.zang.usermanage.model.User; import com.zang.usermanage.service.UserService; public class Client { public static void printUser(User user){ StringBuilder sb = new StringBuilder(); sb.append("id="+user.getId()); sb.append("name="+user.getName()); sb.append("address="+user.getAddress()); sb.append("phone="+user.getPhone()); System.out.println(sb.toString()); } /** * 打印分页信息 * @param pageInfo */ public static <T> void printPageInfo(Page<T> pageInfo){ StringBuilder sb = new StringBuilder(); sb.append("当前是第几页="+pageInfo.getNumber()).append("\\n"); sb.append("当前页查得的记录数="+pageInfo.getNumberOfElements()).append("\\n"); sb.append("每页需要查询的条数="+pageInfo.getSize()).append("\\n"); sb.append("总共符合条件的记录数="+pageInfo.getTotalElements()).append("\\n"); sb.append("总共的页数是="+pageInfo.getTotalPages()).append("\\n"); System.out.println(sb.toString()); } /** * 不分页查询 * @param userService */ public static void testListByConditonNoPage(UserService userService){ List<User> users = userService.getUsersByConditionNoPage("136","路"); if (users!=null){ for (int i=0; i<users.size();i++){ printUser(users.get(i)); } } } /** * 分页查询 * @param userService */ public static void testListByConditonWithPage(UserService userService){ //传入条件和分页信息 Page<User> userPage = userService.getUsersByConditionWithPage("136","路",0,2); //打印分页信息 printPageInfo(userPage); List<User> users = userPage.getContent(); if (users!=null){ for (int i=0; i<users.size();i++){ printUser(users.get(i)); } } } public static void main(String[] arg) throws UserNotFound{ ApplicationContext ac = new ClassPathXmlApplicationContext("applicationContext.xml"); UserService userService = (UserService) ac.getBean("userService"); //testListByConditonNoPage(userService); testListByConditonWithPage(userService); } }
效果:
以上是关于Spring Data JPA入门的主要内容,如果未能解决你的问题,请参考以下文章