spring-data详解之spring-data-jpa：简单三步快速上手spring-data-jpa开发

前言：

基于spring framework 4.x或spring boot 1.x开发环境

务必注意以下版本问题：
Spring framework4.x(Spring boot1.x)对应spring-data1.x

Spring framework5.x(Spring boot2.x)对应spring-data2.x

一、依赖

需要jpa 1.x,hibernate 5.x,spring-data-commons,spring-data-jpa

maven方式：

1. <dependency>
2. <groupId>org.hibernate.javax.persistence</groupId>
3. <artifactId>hibernate-jpa-2.1-api</artifactId>
4. <version>1.0.2.Final</version>
5. </dependency>
6. <dependency>
7. <groupId>org.hibernate</groupId>
8. <artifactId>hibernate-core</artifactId>
9. <version>5.2.16.Final</version>
10. </dependency>
11. <dependency>
12. <groupId>org.hibernate</groupId>
13. <artifactId>hibernate-entitymanager</artifactId>
14. <version>5.2.16.Final</version>
15. </dependency>
16. <dependency>
17. <groupId>org.springframework.data</groupId>
18. <artifactId>spring-data-jpa</artifactId>
19. <version>1.11.11.RELEASE</version>
20. </dependency>

二、环境配置

注意两个扫描器（一个是po实体类扫描，还有一个是dao层接口扫描）

1. <?xml version="1.0" encoding="UTF-8"?>
2. <beans xmlns="http://www.springframework.org/schema/beans"
3. xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
4. xmlns:context="http://www.springframework.org/schema/context"
5. xmlns:tx="http://www.springframework.org/schema/tx"
6. xmlns:jpa="http://www.springframework.org/schema/data/jpa"
7. xsi:schemaLocation="http://www.springframework.org/schema/beans
8. http://www.springframework.org/schema/beans/spring-beans.xsd
9. http://www.springframework.org/schema/context
10. http://www.springframework.org/schema/context/spring-context.xsd
11. http://www.springframework.org/schema/tx
12. http://www.springframework.org/schema/tx/spring-tx.xsd
13. http://www.springframework.org/schema/data/jpa
14. http://www.springframework.org/schema/data/jpa/spring-jpa.xsd">
15. <!-- eguid博客所有原创文章均采用知识共享署名-相同方式共享 3.0 中国大陆许可协议进行许可。如有转载请注明博客地址：https://blog.csdn.net/eguid_1/article/details/80018676-->
16. <!-- druid连接池 -->
17. <bean id="dataSource" class="com.alibaba.druid.pool.DruidDataSource" init-method="init" destroy-method="close">
18. <property name="driverClassName" value="${jdbc.driverClassName}" />
19. <property name="url" value="${jdbc.url}" />
20. <property name="username" value="${jdbc.username}" />
21. <property name="password" value="${jdbc.password}" />
22. <property name="maxActive" value="${jdbc.maxActive}" />
23. <property name="initialSize" value="${jdbc.initialSize}" />
24. <property name="maxWait" value="${jdbc.maxWait}" />
25. <property name="maxIdle" value="${jdbc.maxIdle}" />
26. <property name="minIdle" value="${jdbc.minIdle}" />
27. <property name="removeAbandoned" value="${jdbc.removeAbandoned}" />
28. <property name="removeAbandonedTimeout" value="${jdbc.removeAbandonedTimeout}" />
29. <property name="testWhileIdle" value="${jdbc.testWhileIdle}" />
30. <property name="validationQuery" value="${jdbc.validationQuery}"/>
31. <property name="validationQueryTimeout" value="${jdbc.validationQueryTimeout}" />
32. <property name="timeBetweenEvictionRunsMillis" value="${jdbc.timeBetweenEvictionRunsMillis}" />
33. <property name="numTestsPerEvictionRun" value="${jdbc.numTestsPerEvictionRun}" />
34.  
35. <!-- 打开PSCache，并且指定每个连接上PSCache的大小 -->
36.         <property name="poolPreparedStatements" value="false" />
37.         <property name="maxPoolPreparedStatementPerConnectionSize" value="20" />
38.  
39.         <!-- 配置监控统计拦截的filters -->
40.         <property name="filters" value="stat,wall"/>
41.         <property name="connectionProperties" value="druid.stat.slowSqlMillis=5000" />
42. </bean>
43.  
44. <!-- JPA工厂对象 -->
45. <bean id="entityManagerFactory" class="org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean">
46. <property name="dataSource" ref="dataSource" />
47.         <!-- 扫描此包下的所有Entity,进行ORM映射(这里的实体类包路径需要修改) -->
48.         <property name="packagesToScan" value="cc.eguid.xxx.pojo.po" />
49.     <property name="persistenceProvider">
50.     <bean class="org.hibernate.jpa.HibernatePersistenceProvider" />
51.     </property>
52.     <property name="jpaVendorAdapter">
53. <bean class="org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter">
54. <property name="generateDdl" value="false" />
55. <property name="database" value="MYSQL" />
56. <property name="databasePlatform" value="org.hibernate.dialect.MySQLDialect" />
57. <property name="showSql" value="true" />
58. </bean>
59. </property>
60. <property name="jpaDialect">
61. <bean class="org.springframework.orm.jpa.vendor.HibernateJpaDialect" />
62. </property>
63. <property name="jpaPropertyMap">
64. <map>
65. <entry key="hibernate.query.substitutions" value="true 1, false 0" />
66. <entry key="hibernate.default_batch_fetch_size" value="16" />
67. <entry key="hibernate.max_fetch_depth" value="2" />
68. <entry key="hibernate.generate_statistics" value="true" />
69. <entry key="hibernate.bytecode.use_reflection_optimizer" value="true" />
70. <entry key="hibernate.cache.use_second_level_cache" value="false" />
71. <entry key="hibernate.cache.use_query_cache" value="false" />
72. </map>
73. </property>
74.     </bean>
75.  
76.     <!-- 使用声明式事务管理 -->
77.     <tx:annotation-driven transaction-manager="transactionManager" proxy-target-class="true" />
78.  
79.     <!-- JPA事务管理器 -->
80. <bean id="transactionManager" class="org.springframework.orm.jpa.JpaTransactionManager">
81. <property name="entityManagerFactory" ref="entityManagerFactory"/>
82. </bean>
83.  
84.     <!--扫描 JPA持久化接口，spring-data-jpa会自动生成实现类(这里的repostory接口包路径需要修改)-->
85.     <jpa:repositories base-package="cc.eguid.xxx.dao" entity-manager-factory-ref="entityManagerFactory" transaction-manager-ref="transactionManager"/>
86.  
87. </beans>

三、实体类和Repository接口

（1）编写dao层接口（不需实现类，spring-data-jpa会自动生成实现类）

1. import org.springframework.data.repository.CrudRepository;
2.  
3. /**
4. * spring-data-jpa自动生成实现类，简化dao层开发
5. * @author eguid
6. *
7. */
8. public interface UserRepository extends CrudRepository<GameUserinfo, Integer>{
9.     
10. GameUserinfo findByUsername(String username);
11.  
12. }

（2）自动生成的ORM映射Entity（用JPA生成工具生成的）

1. /**
2. * The persistent class for the game_userinfo database table.
3. *
4. */
5. @Entity
6. @Table(name="userinfo")
7. @NamedQuery(name="Userinfo.findAll", query="SELECT g FROM Userinfo g")
8. public class Userinfo extends BaseEntity {
9. private static final long serialVersionUID = 1L;
10.  
11. @Id
12. @GeneratedValue(strategy=GenerationType.AUTO)
13. @Column(unique=true, nullable=false)
14. private Integer userid;
15.  
16. private Timestamp createtime;
17.  
18. @Column(length=50)
19. private String nickname;
20.  
21. @Column(length=100)
22. private String password;
23.  
24. private int type;
25.  
26. @Column(length=50)
27. private String username;
28.  
29. //bi-directional many-to-many association to Roleinfo
30. @ManyToMany
31. @JoinTable(
32. name="userrole"
33. , joinColumns={
34. @JoinColumn(name="userid", nullable=false)
35. }
36. , inverseJoinColumns={
37. @JoinColumn(name="roleid", nullable=false)
38. }
39. )
40. private List<roleinfo> roleinfos;
41.  
42. public Userinfo() {
43. }
44.  
45. public Integer getUserid() {
46. return this.userid;
47. }
48.  
49. public void setUserid(Integer userid) {
50. this.userid = userid;
51. }
52.  
53. public Timestamp getCreatetime() {
54. return this.createtime;
55. }
56.  
57. public void setCreatetime(Timestamp createtime) {
58. this.createtime = createtime;
59. }
60.  
61. public String getNickname() {
62. return this.nickname;
63. }
64.  
65. public void setNickname(String nickname) {
66. this.nickname = nickname;
67. }
68.  
69. public String getPassword() {
70. return this.password;
71. }
72.  
73. public void setPassword(String password) {
74. this.password = password;
75. }
76.  
77. public int getType() {
78. return this.type;
79. }
80.  
81. public void setType(int type) {
82. this.type = type;
83. }
84.  
85. public String getUsername() {
86. return this.username;
87. }
88.  
89. public void setUsername(String username) {
90. this.username = username;
91. }
92.  
93. public List<Roleinfo> getRoleinfos() {
94. return this.roleinfos;
95. }
96.  
97. public void setRoleinfos(List<Roleinfo> roleinfos) {
98. this.roleinfos = roleinfos;
99. }
100.  
101. }

四、总结

1、添加依赖（添加spring-data及spring-data-jpa依赖包）

2、配置jpa环境（配置dao扫描路径和实体类扫描路径）

3、编写实体类和dao层接口（如果是简单的单表增删改查操作，直接继承CrudRepository接口即可，基本不需要写代码）

jpa单表操作基本无可挑剔，涉及多表操作需要手写hql语句或jpa

实体类是用工具生成的，所以实际上只需要写一个dao接口即可