工具篇-Spring boot JPA多数据源

写这篇博文是因为这个东西坑太多，首先说明下边实现的多数据源不是动态切换的，应该算是静态的。另外，如果对Spring JPA不熟悉的话，可以参见：SpringBoot 中 JPA 的使用

坑一、pom文件

pom中spring boot以及mysql connector的版本一定要注意。

  <parent>
          <groupId>org.springframework.boot</groupId>
          <artifactId>spring-boot-starter-parent</artifactId>
          <version>1.5.8.RELEASE</version>
          <relativePath/>
      </parent>

      <properties>
          <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
          <project.reporting.outputEncoding>UTF-8</project.reporting.outputEncoding>
          <springboot.version>1.5.8.RELEASE</springboot.version>
          <java.version>1.8</java.version>
          <spring.boot.mainclass>xxxx.data.xxxx.Application</spring.boot.mainclass>
      </properties>

      <dependencies>
          <dependency>
              <groupId>io.springfox</groupId>
              <artifactId>springfox-swagger2</artifactId>
              <exclusions>
                  <exclusion>
                      <artifactId>spring-aop</artifactId>
                      <groupId>org.springframework</groupId>
                  </exclusion>
                  <exclusion>
                      <artifactId>spring-beans</artifactId>
                      <groupId>org.springframework</groupId>
                  </exclusion>
                  <exclusion>
                      <artifactId>spring-context</artifactId>
                      <groupId>org.springframework</groupId>
                  </exclusion>
                  <exclusion>
                      <artifactId>spring-core</artifactId>
                      <groupId>org.springframework</groupId>
                  </exclusion>
                  <exclusion>
                      <artifactId>spring-expression</artifactId>
                      <groupId>org.springframework</groupId>
                  </exclusion>
                  <exclusion>
                      <artifactId>jackson-annotations</artifactId>
                      <groupId>com.fasterxml.jackson.core</groupId>
                  </exclusion>
              </exclusions>
          </dependency>
          <dependency>
              <groupId>io.springfox</groupId>
              <artifactId>springfox-swagger-ui</artifactId>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter</artifactId>
              <version>${springboot.version}</version>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-web</artifactId>
              <version>${springboot.version}</version>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-data-jpa</artifactId>
              <version>${springboot.version}</version>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-starter-test</artifactId>
              <version>${springboot.version}</version>
              <scope>test</scope>
          </dependency>

          <dependency>
              <groupId>mysql</groupId>
              <artifactId>mysql-connector-java</artifactId>
              <version>5.1.36</version>
          </dependency>
          <dependency>
              <groupId>junit</groupId>
              <artifactId>junit</artifactId>
              <version>4.12</version>
          </dependency>
          <dependency>
              <groupId>org.springframework.boot</groupId>
              <artifactId>spring-boot-autoconfigure</artifactId>
              <version>1.5.8.RELEASE</version>
          </dependency>
      </dependencies>

      <build>
          <plugins>
              <plugin>
                  <groupId>org.springframework.boot</groupId>
                  <artifactId>spring-boot-maven-plugin</artifactId>
                  <version>${springboot.version}</version>
                  <configuration>
                      <!--<fork>true</fork>
                      <mainClass>${spring.boot.mainclass}</mainClass>-->
                      <layout>ZIP</layout>
                  </configuration>
                  <executions>
                      <execution>
                          <goals>
                              <goal>repackage</goal>
                          </goals>
                      </execution>
                  </executions>
              </plugin>
          </plugins>
      </build>

坑二、config文件

有DataSourceConfig、PrimaryConfig、SecondaryConfig三个配置文件，路径大概是这样的：

首先DataSourceConfig：

 /**
  * Multi datasource profile.
  * @date 2019/04/26 10:58
  */

 @Configuration
 public class DataSourceConfig {
     @Bean(name = "primaryDataSource")
     @Qualifier("primaryDataSource")
     @Primary
     @ConfigurationProperties(prefix = "spring.datasource.primary")
     public DataSource primaryDataSource() {
         return DataSourceBuilder.create().build();
     }

     @Bean(name = "secondaryDataSource")
     @Qualifier("secondaryDataSource")
     @ConfigurationProperties(prefix = "spring.datasource.secondary")
     public DataSource secondaryDataSource() {
         return DataSourceBuilder.create().build();
     }
 }

PrimaryConfig：

 @Configuration
 @EnableTransactionManagement
 @EnableJpaRepositories(
         entityManagerFactoryRef="entityManagerFactoryPrimary",
         transactionManagerRef="transactionManagerPrimary",
         basePackages = {"xxxx.data.xxxx.dao.primary.*"})
 public class PrimaryConfig {

     @Autowired
     @Qualifier("primaryDataSource")
     private DataSource primaryDataSource;

     @Autowired(required = false)
     private JpaProperties jpaProperties;

     /**
      * EntityManager profile.
       */
     @Primary
     @Bean(name = "entityManagerPrimary")
     public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
         return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
     }

     /**
      * EntityManagerFactory profile.
      */
     @Primary
     @Bean(name = "entityManagerFactoryPrimary")
     public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder) {
         return builder.dataSource(primaryDataSource)
                 .properties(getVendorProperties(primaryDataSource))
                 .packages("xxxx.data.xxxx.entity.primary.*")
                 .persistenceUnit("primaryPersistenceUnit")
                 .build();
     }

     /**
      * Jpa profile.
      */
     private Map<String, String> getVendorProperties(DataSource dataSource) {
         return jpaProperties.getHibernateProperties(dataSource);
     }

     /**
      * Transaction profile.
      */
     @Primary
     @Bean(name = "transactionManagerPrimary")
     public PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder) {
         return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
     }
 }

SecondaryConfig:

 @Configuration
 @EnableTransactionManagement
 @EnableJpaRepositories(
         entityManagerFactoryRef="entityManagerFactorySecondary",
         transactionManagerRef="transactionManagerSecondary",
         basePackages = {"xxxx.data.xxxx.dao.secondary.*"})
 public class SecondaryConfig {
     @Autowired
     @Qualifier("secondaryDataSource")
     private DataSource secondaryDataSource;

     @Autowired(required = false)
     private JpaProperties jpaProperties;

     /**
      * EntityManager profile.
      */
     @Bean(name = "entityManagerSecondary")
     public EntityManager entityManager(EntityManagerFactoryBuilder builder) {
         return entityManagerFactorySecondary(builder).getObject().createEntityManager();
     }

     /**
      * EntityManagerFactory profile.
      */
     @Bean(name = "entityManagerFactorySecondary")
     public LocalContainerEntityManagerFactoryBean entityManagerFactorySecondary (EntityManagerFactoryBuilder builder) {
         return builder
                 .dataSource(secondaryDataSource)
                 .properties(getVendorProperties(secondaryDataSource))
                 .packages("xxxx.data.xxxx.entity.secondary.*")
                 .persistenceUnit("secondaryPersistenceUnit")
                 .build();
     }

     /**
      * Jpa profile.
      */
     private Map<String, String> getVendorProperties(DataSource dataSource) {
         return jpaProperties.getHibernateProperties(dataSource);
     }

     /**
      * Transaction profile.
      */
     @Bean(name = "transactionManagerSecondary")
     public PlatformTransactionManager transactionManagerSecondary(EntityManagerFactoryBuilder builder) {
         return new JpaTransactionManager(entityManagerFactorySecondary(builder).getObject());
     }

 }

上边这些配不好，就会报一些烂七八糟的错误：

org.springframework.beans.factory.UnsatisfiedDependencyException: Error creating bean with name 'operationLogAspect': Unsatisfied dependency expressed through field 'jobOperationLogDao'; nested exception is org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'xxxxxxDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class xxxxxx
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor$AutowiredFieldElement.inject(AutowiredAnnotationBeanPostProcessor.java:588) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.annotation.InjectionMetadata.inject(InjectionMetadata.java:88) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.annotation.AutowiredAnnotationBeanPostProcessor.postProcessPropertyValues(AutowiredAnnotationBeanPostProcessor.java:366) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.populateBean(AbstractAutowireCapableBeanFactory.java:1264) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.doCreateBean(AbstractAutowireCapableBeanFactory.java:553) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.createBean(AbstractAutowireCapableBeanFactory.java:483) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory$1.getObject(AbstractBeanFactory.java:306) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.DefaultSingletonBeanRegistry.getSingleton(DefaultSingletonBeanRegistry.java:230) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.doGetBean(AbstractBeanFactory.java:302) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.AbstractBeanFactory.getBean(AbstractBeanFactory.java:197) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.beans.factory.support.DefaultListableBeanFactory.preInstantiateSingletons(DefaultListableBeanFactory.java:761) ~[spring-beans-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.finishBeanFactoryInitialization(AbstractApplicationContext.java:867) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.context.support.AbstractApplicationContext.refresh(AbstractApplicationContext.java:543) ~[spring-context-4.3.12.RELEASE.jar:4.3.12.RELEASE]
    at org.springframework.boot.context.embedded.EmbeddedWebApplicationContext.refresh(EmbeddedWebApplicationContext.java:122) ~[spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at org.springframework.boot.SpringApplication.refresh(SpringApplication.java:693) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at org.springframework.boot.SpringApplication.refreshContext(SpringApplication.java:360) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:303) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1118) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at org.springframework.boot.SpringApplication.run(SpringApplication.java:1107) [spring-boot-1.5.8.RELEASE.jar:1.5.8.RELEASE]
    at yidian.data.bear.Application.main(Application.java:18) [classes/:na]
Caused by: org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'xxxxxxxDao': Invocation of init method failed; nested exception is java.lang.IllegalArgumentException: Not a managed type: class ......
    at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.
    ... 19 common frames omitted
Caused by: java.lang.IllegalArgumentException: Not a managed type: class 

当然，如果你使用Springboot2.x的话，getHibernateProperties方法会报错的，对于这种情况，可以参考：https://blog.csdn.net/MrCoderStack/article/details/88658069，附上上边链接中的一张图片。

坑三、数据库配置文件

application-test.properties中配置了两个数据源，注意.url不好使的话，换成.jdbc.url试试：

 #########################################################
 ### Primary DataSource -- DataSource 1 configuration  ###
 #########################################################
 spring.datasource.primary.url=jdbc:mysql://ip:3307/数据库名
 spring.datasource.primary.username=用户名
 spring.datasource.primary.password=密码
 spring.datasource.primary.driver-class-name=com.mysql.jdbc.Driver

 #########################################################
 ### Secondary DataSource -- DataSource 2 configuration ##
 #########################################################
 spring.datasource.secondary.url=jdbc:mysql://ip:3309/数据库名
 spring.datasource.secondary.username=用户名
 spring.datasource.secondary.password=密码
 spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver

 #########################################################
 ### Java Persistence Api --  Spring jpa configuration ###
 #########################################################
 # Specify the DBMS
 spring.jpa.database=mysql
 spring.jpa.database-platform=org.hibernate.dialect.MySQL5InnoDBDialect
 # Hibernate ddl auto (create, create-drop, update, validate)
 spring.jpa.hibernate.ddl-auto=validate
 # Naming strategy
 spring.jpa.hibernate.naming.physical-strategy=org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl
 # stripped before adding them to the entity manager
 #spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5Dialect

坑四、Entity映射无自增Id数据库表

JPA entity映射数据库表时需要一个唯一Id，而有的数据库表没有id怎么办，但是如果存在联合主键的话你可以采取IdClass注解的方式，这样的好处是写dao层代码方便，首先把联合主键封装成一个类，如下所示：

 public class ScPK implements Serializable {
     @Column(name = "student_name")
     private String studentName;
     @Column(name = "course_name")
     private String courseName;
     private String score;

     public String getStudentName() {
         return studentName;
     }

     public void setStudentName(String studentName) {
         this.studentName = studentName;
     }

     public String getCourseName() {
         return courseName;
     }

     public void setCourseName(String courseName) {
         this.courseName = courseName;
     }

     public String getScore() {
         return score;
     }

     public void setScore(String score) {
         this.score = score;
     }
 }

然后是实体类：

 @Entity
 @Table(name = "test")
 @IdClass(ScPK.class)
 public class ScEntity {
     @Id
     @Column(name = "student_name")
     private String studentName;
     @Id
     @Column(name = "course_name")
     private String courseName;

     private String score;

     public String getStudentName() {
         return studentName;
     }

     public void setStudentName(String studentName) {
         this.studentName = studentName;
     }

     public String getCourseName() {
         return courseName;
     }

     public void setCourseName(String courseName) {
         this.courseName = courseName;
     }

     public String getScore() {
         return score;
     }

     public void setScore(String score) {
         this.score = score;
     }
 }

也附上dao层代码吧，这里studentName、courseName与实体类中属性保持一致，与数据库表无关：

 @Repository
 public interface ScDao extends JpaRepository<ScEntity, Long> {

     @Query("select l from ScEntity l where l.studentName = :studentName and l.courseName = :courseName")
     ScEntity findAllByStudentNameAndCourseName(@Param("studentName") String studentName, @Param("courseName") String courseName);
 }

坑五、SpringBoot项目改多数据源后debug启动不起来

我就纳闷怎么改了多数据源，debug启动服务就起不来了，用postman也访问不了。有位大哥or大姐（https://www.cnblogs.com/fightingting/p/9683811.html）说自己几个月一直启动很慢，我是直接起不来了偶偶，幸亏ta提醒：idea左下角出现一行小字，Method breakpoints may dramatically slow down debugging，启动Springboot项目之前把断点去掉就解决了。

坑刘、Hibernate整合SpringBoot配置多数据源后8小时无操作数据库连接失效

问题：应用8小时不访问数据库，数据库连接自动失效访问失败，报错如下：

解决办法：在上面的properties中增加如下配置：

 spring.datasource.primary.test-while-idle=true
 spring.datasource.secondary.test-while-idle=true