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