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  • 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
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  • 原文地址：https://www.cnblogs.com/eguid/p/9667152.html
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