Jpa与Druid线程池及Spring Boot整合(二): spring-boot-starter-data-jpa 踏坑异常处理方案

                    

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 Jpa与Druid线程池及Spring Boot整合(一)

Jpa与Druid线程池及Spring Boot整合(二)：几个坑

附录官网文档：core.domain-events域事件

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从聚合根发布事件

存储库管理的实体是聚合根。在领域驱动设计应用程序中，这些聚合根通常会发布领域事件。Spring Data 提供了一个名为 的注释@DomainEvents，您可以在聚合根的方法上使用该注释，以使该发布尽可能简单，如以下示例所示：

示例 43. 从聚合根公开域事件

class AnAggregateRoot {@DomainEvents (1)Collection<Object> domainEvents() {// … return events you want to get published here}@AfterDomainEventPublication (2)void callbackMethod() {// … potentially clean up domain events list}
}

	使用的方法@DomainEvents可以返回单个事件实例或事件集合。它不能接受任何参数。
	发布所有事件后，我们有一个用 注释的方法@AfterDomainEventPublication。您可以使用它来潜在地清理要发布的事件列表（以及其他用途）。

每次调用以下 Spring 数据存储库方法之一时都会调用这些方法：

• save(…),saveAll(…)

• delete(…), deleteAll(…), deleteAllInBatch(…),deleteInBatch(…)

请注意，这些方法将聚合根实例作为参数。这就是为什么deleteById(…)明显不存在的原因，因为实现可能会选择发出删除实例的查询，因此我们首先永远无法访问聚合实例。

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在使用Spring Boot JPA时，open-in-view 选项默认为true。启动时在日志中会出现警告。 

一坑：druid与jpa整合，启动出现如下警告：

JpaBaseConfiguration$JpaWebConfiguration : spring.jpa.open-in-view is enabled by default. Therefore, database queries may be performed during view rendering. Explicitly configure spring.jpa.open-in-view to disable this warning

 处理方案:

按照日志要求将 open-in-view=false。再次启动，如果在实体类中外键字段使用了懒加载模式，在视图层中调用数据时，则会出现 no session 异常。

解决方法：手动注册OpenEntityManagerInViewFilter过滤器，改变session的生命周期，当web请求关闭时才结束session。
 

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  javaConfig注入bean

@Bean
public FilterRegistrationBean<OpenEntityManagerInViewFilter> registerOpenEntityManagerInViewFilterBean() {FilterRegistrationBean<OpenEntityManagerInViewFilter> registrationBean = new FilterRegistrationBean<>();OpenEntityManagerInViewFilter filter = new OpenEntityManagerInViewFilter();registrationBean.setFilter(filter);registrationBean.setOrder(5);return registrationBean;
}

解疑：

如果使用的是 JPA 则对应OpenEntityManagerInViewFilter,Hibernate对应OpenSessionInViewFilter
疑问：

registrationBean.setOrder(5)，order为什么是5
OpenSessionInViewInterceptor&OpenSessionInViewFilter,OpenEntityManagerInViewInterceptor&OpenEntityManagerInViewFilter这几个类的区别以及使的的场景
 

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重新启动: 正常：

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二坑:   springboot整合JPA出现异常java.lang.IllegalArgumentException: Not a managed type: class xx

方案: 一

启动类或者JavaConfig添加添加扫描实体的路径:
@EntityScan(basePackages = "org.jd.websocket.auth.data.reactor.jpa")
@EnableTransactionManagement // 开启事务的支持
@EnableJpaRepositories(basePackages = {"org.jd.websocket.auth.data.reactor.repository","org.jd.websocket.auth.data.reactor.jpa"},includeFilters = {@ComponentScan.Filter(type = FilterType.REGEX, pattern = ".*CrudRepository")},excludeFilters = {@ComponentScan.Filter(type = FilterType.REGEX, pattern = ".*SomeOtherRepository")})

 方案: 二

@Configuration     javaConfig中注入Bean

@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();vendorAdapter.setGenerateDdl(true);LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();factory.setJpaVendorAdapter(vendorAdapter);// entity扫描的包路径factory.setPackagesToScan("org.jd.websocket.auth.data.reactor.jpa");factory.setDataSource(dataSource());return factory;
}

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@Value("${spring.datasource.url}")
private String dbUrl;@Value("${spring.datasource.username}")
private String username;
@Value("${spring.datasource.password}")
private String password;
@Value("${spring.datasource.driver-class-name}")
private String driverClassName;@Value("${spring.datasource.initialSize}")
private int initialSize;
@Value("${spring.datasource.minIdle}")
private int minIdle;
@Value("${spring.datasource.maxActive}")
private int maxActive;
@Value("${spring.datasource.maxWait}")
private int maxWait;
@Value("${spring.datasource.timeBetweenEvictionRunsMillis}")
private int timeBetweenEvictionRunsMillis;
@Value("${spring.datasource.minEvictableIdleTimeMillis}")
private int minEvictableIdleTimeMillis;
@Value("${spring.datasource.validationQuery}")
private String validationQuery;
@Value("${spring.datasource.testWhileIdle}")
private boolean testWhileIdle;
@Value("${spring.datasource.testOnBorrow}")
private boolean testOnBorrow;
@Value("${spring.datasource.testOnReturn}")
private boolean testOnReturn;
@Value("${spring.datasource.poolPreparedStatements}")
private boolean poolPreparedStatements;
@Value("${spring.datasource.maxPoolPreparedStatementPerConnectionSize}")
private int maxPoolPreparedStatementPerConnectionSize;
@Value("${spring.datasource.filters}")
private String filters;
@Value("{spring.datasource.connectionProperties}")
private String connectionProperties;@Bean
@Primary
public DataSource dataSource() {DruidDataSource datasource = new DruidDataSource();datasource.setUrl(dbUrl);datasource.setUsername(username);datasource.setPassword(password);datasource.setDriverClassName(driverClassName);// configurationdatasource.setInitialSize(initialSize);datasource.setMinIdle(minIdle);datasource.setMaxActive(maxActive);datasource.setMaxWait(maxWait);datasource.setTimeBetweenEvictionRunsMillis(timeBetweenEvictionRunsMillis);datasource.setMinEvictableIdleTimeMillis(minEvictableIdleTimeMillis);datasource.setValidationQuery(validationQuery);datasource.setTestWhileIdle(testWhileIdle);datasource.setTestOnBorrow(testOnBorrow);datasource.setTestOnReturn(testOnReturn);datasource.setPoolPreparedStatements(poolPreparedStatements);datasource.setMaxPoolPreparedStatementPerConnectionSize(maxPoolPreparedStatementPerConnectionSize);try {datasource.setFilters(filters);} catch (SQLException e) {System.err.println("druid configuration initialization filter: " + e);}datasource.setConnectionProperties(connectionProperties);return datasource;
}@Bean
public LocalContainerEntityManagerFactoryBean entityManagerFactory() {HibernateJpaVendorAdapter vendorAdapter = new HibernateJpaVendorAdapter();vendorAdapter.setGenerateDdl(true);LocalContainerEntityManagerFactoryBean factory = new LocalContainerEntityManagerFactoryBean();factory.setJpaVendorAdapter(vendorAdapter);// entity扫描的包路径factory.setPackagesToScan("org.jd.websocket.auth.data.reactor.jpa");factory.setDataSource(dataSource());return factory;
}

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坑三:    多数据源注入,事务失效|解决方案;

* @Transactiona在多数据源下失效
* 在多数据源的情况下，如果transactionManager进行了分开配置，比如这里针对三个数据源配置了三个transactionManager
* ===========================================================================================================
* @Bean("formTransactionManager")
* public PlatformTransactionManager transactionManager(EntityManagerFactoryBuilder builder) {
*     return new JpaTransactionManager(Objects.requireNonNull(entityManagerFactory(builder).getObject()));
* }
*=============================================================================================================
* @Bean("fileTransactionManager")
* public PlatformTransactionManager transactionManager(EntityManagerFactoryBuilder builder) {
*     return new JpaTransactionManager(Objects.requireNonNull(entityManagerFactory(builder).getObject()));
* }
* ============================================================================================================
* @Primary
* @Bean("userTransactionManager")
* public PlatformTransactionManager transactionManager(EntityManagerFactoryBuilder builder) {
*     return new JpaTransactionManager(Objects.requireNonNull(entityManagerFactory(builder).getObject()));
* }
* =============================================================================================================
*
* 那么在使用@Transactional的时候需要指定transactionManager
* @Transactional("formTransactionManager")

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@EnableTransactionManagement // 开启事务的支持

可以访问下druid监控相关数据:

http://localhost:9999/druid/

输入上面的账号和密码:  可以查看不同的选项卡,能帮助我们排查一些数据库相关问题