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在之前的文章中我們已經(jīng)介紹了SpringJDBC的多數(shù)據(jù)源實(shí)現(xiàn)（在一個項(xiàng)目中操作多個數(shù)據(jù)庫），比較常見的多數(shù)據(jù)源的支持方式有兩種：
把數(shù)據(jù)源作為參數(shù)傳入到調(diào)用方法內(nèi)部，需要我們手動傳參。 不同的包下面的接口函數(shù)自動注入不同的數(shù)據(jù)源。 第一種方法比較麻煩，會增加額外的代碼。所以我們使用第二種方式來實(shí)現(xiàn)JPA的多數(shù)據(jù)源支持。 首先來修改.yml文件，配置兩個數(shù)據(jù)源： server: port: 8888spring: jackson: date-format: yyyy-MM-dd HH:mm:ss time-zone: GMT+8 datasource: Family: driver-class-name: com.mysql.cj.jdbc.Driver jdbc-url: mysql://localhost:3306/Family?useUnicode=true&characterEncoding=utf-8&useSSL=false username: root password: 123456 Family2: driver-class-name: com.mysql.cj.jdbc.Driver jdbc-url: mysql://localhost:3306/Family2?useUnicode=true&characterEncoding=utf-8&useSSL=false username: root password: 123456 jpa: # Hibernate 創(chuàng)建數(shù)據(jù)庫表的時候，默認(rèn)使用的數(shù)據(jù)庫存儲引擎是 MyISAM # database-platform在建表的時候?qū)⒋鎯σ媲袚Q為 InnoDB database-platform: org.hibernate.dialect.MySQL5InnoDBDialect hibernate: # 在Hibernate每次加載的時候，都會驗(yàn)證數(shù)據(jù)庫中的表結(jié)構(gòu)是否跟model類中字段的定義是一致的，如果不一致就拋出異常 ddl-auto: validate naming: physical-strategy: org.hibernate.boot.model.naming.PhysicalNamingStrategyStandardImpl database: mysql # 在日志打印出執(zhí)行的sql語句 show-sql: true1234567891011121314151617181920212223242526272829303132復(fù)制代碼類型：[java] 在Dao文件下創(chuàng)建文件夾db和db2，將model中的Pets.java移動到db文件下并把Dao文件下原有的PetsRepository也移動到db文件夾下。在db2下新創(chuàng)建一個實(shí)體類Doctor和DoctorRepository接口：
package com.javafamily.familydemo.dao.db2;import lombok.AllArgsConstructor;import lombok.Builder;import lombok.Data;import lombok.NoArgsConstructor;import javax.persistence.*;@Data@Entity@Builder@Table(name = "doctor")public class Doctor { @Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
private long id; @Column(nullable = false)
private String name; @Column(nullable = false)
private String title;
}123456789101112131415161718192021222324復(fù)制代碼類型：[java]package com.javafamily.familydemo.dao.db2;import com.javafamily.familydemo.model.Pets;import org.springframework.data.jpa.repository.JpaRepository;public interface DoctorRepository extends JpaRepository<Doctor, Long> {
}12345678復(fù)制代碼類型：[java]現(xiàn)在我們需要實(shí)現(xiàn)將Family數(shù)據(jù)源給PetsRepository使用,Family2數(shù)據(jù)源給db2使用。 接下來我們來實(shí)現(xiàn)配置：在config文件下創(chuàng)建JPAFamilyConfig.java和JPAFamily2Config.java package com.javafamily.familydemo.config;import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.jdbc.DataSourceBuilder;import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.Primary;import org.springframework.data.jpa.repository.config.EnableJpaRepositories;import org.springframework.orm.jpa.JpaTransactionManager;import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import org.springframework.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;import javax.annotation.Resource;import javax.persistence.EntityManager;import javax.sql.DataSource;import java.util.Map;@Configuration@EnableTransactionManagement@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactoryFamily",
transactionManagerRef = "transactionManagerFamily",
// 換成你自己的Repository所在位置
basePackages = {"com.javafamily.familydemo.dao.db"})public class JPAFamilyConfig { @Resource
private JpaProperties jpaProperties; @Primary
@Bean(name = "familyDataSource")
@ConfigurationProperties(prefix = "spring.datasource.family")
public DataSource familyDataSource() { return DataSourceBuilder.create().build();
} @Primary
// 實(shí)體管理器
@Bean(name = "entityManagerFamily")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) { return entityManagerFactoryFamily(builder).getObject().createEntityManager();
} @Primary
// 實(shí)體工廠
@Bean(name = "entityManagerFactoryFamily")
public LocalContainerEntityManagerFactoryBean entityManagerFactoryFamily(EntityManagerFactoryBuilder builder) { return builder.dataSource(familyDataSource())
.properties(jpaProperties.getProperties()) // 換成你自己的實(shí)體類所在位置
.packages("com.javafamily.familydemo.dao.db")
.persistenceUnit("familyPersistenceUnit")
.build();
} @Primary
// 事務(wù)管理器
@Bean(name = "transactionManagerFamily")
public PlatformTransactionManager transactionManagerFamily(EntityManagerFactoryBuilder builder) { return new JpaTransactionManager(entityManagerFactoryFamily(builder).getObject());
}
}1234567891011121314151617181920212223242526272829303132333435363738394041424344454647484950515253545556575859606162636465666768復(fù)制代碼類型：[java]package com.javafamily.familydemo.config;import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.jdbc.DataSourceBuilder;import org.springframework.boot.orm.jpa.EntityManagerFactoryBuilder;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.data.jpa.repository.config.EnableJpaRepositories;import org.springframework.orm.jpa.JpaTransactionManager;import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import org.springframework.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;import javax.annotation.Resource;import javax.persistence.EntityManager;import javax.sql.DataSource;@Configuration@EnableTransactionManagement@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactoryFamily2",
transactionManagerRef = "transactionManagerFamily2",
// 換成你自己的Repository所在位置
basePackages = {"com.javafamily.familydemo.dao.db2"})public class JPAFamily2Config { @Resource
private JpaProperties jpaProperties; @Bean(name = "family2DataSource")
@ConfigurationProperties(prefix = "spring.datasource.family2")
public DataSource family2DataSource() { return DataSourceBuilder.create().build();
} @Bean(name = "entityManagerFamily2")
public EntityManager entityManager(EntityManagerFactoryBuilder builder) { return entityManagerFactoryFamily2(builder).getObject().createEntityManager();
} @Bean(name = "entityManagerFactoryFamily2")
public LocalContainerEntityManagerFactoryBean entityManagerFactoryFamily2(EntityManagerFactoryBuilder builder) { return builder.dataSource(family2DataSource())
.properties(jpaProperties.getProperties()) // 換成你自己的實(shí)體類所在位置
.packages("com.javafamily.familydemo.dao.db2")
.persistenceUnit("family2PersistenceUnit")
.build();
} @Bean(name = "transactionManagerFamily2")
public PlatformTransactionManager transactionManagerFamily2(EntityManagerFactoryBuilder builder) { return new JpaTransactionManager(entityManagerFactoryFamily2(builder).getObject());
}
}12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758復(fù)制代碼類型：[java]完成上述配置后，再編寫測試類對多數(shù)據(jù)源進(jìn)行測試。 package com.javafamily.familydemo;import com.javafamily.familydemo.dao.db.Pets;import com.javafamily.familydemo.dao.db.PetsRepository;import com.javafamily.familydemo.dao.db2.Doctor;import com.javafamily.familydemo.dao.db2.DoctorRepository;import org.junit.jupiter.api.Test;import org.junit.jupiter.api.extension.ExtendWith;import org.springframework.boot.test.context.SpringBootTest;import org.springframework.test.context.junit.jupiter.SpringExtension;import javax.annotation.Resource;import java.util.Date;@ExtendWith(SpringExtension.class)@SpringBootTestpublic class KeyWordsTest { @Resource
private PetsRepository petsRepository; @Resource
private DoctorRepository doctorRepository; @Test
public void Test() {
Pets pets = petsRepository.findPetsByName("fish");
System.out.println(pets);
} @Test
public void jpaTest() {
Pets pets = Pets.builder()
.id(2L)
.name("JavaFamily")
.varieties("chai")
.createTime(new Date())
.build();
Doctor doctor = Doctor.builder()
.name("petsDoctor").title("director").build(); // 先構(gòu)造一個Pets對象pets，這個操作針對db
petsRepository.save(pets); //在構(gòu)造一個Doctor對象doctor，這個操作針對db2
doctorRepository.save(doctor);
}
}1234567891011121314151617181920212223242526272829303132333435363738394041424344454647復(fù)制代碼類型：[java]執(zhí)行代碼，查看數(shù)據(jù)庫會發(fā)現(xiàn)兩張表的數(shù)據(jù)都已經(jīng)插入成功。
當(dāng)有異常發(fā)生時按照正常的邏輯，兩條數(shù)據(jù)都應(yīng)該插入失敗。 我們先將數(shù)據(jù)庫中之前的數(shù)據(jù)全部清除，之后改寫PetsServiceImpl.java的save方法，并且添加分母為0的異常。 @Resource
private PetsRepository petsRepository; @Resource
private DoctorRepository doctorRepository; @Resource
private Mapper dozerMapper; @Transactional
public void savePets(PetsVO pets) {
Pets petsPO = dozerMapper.map(pets, Pets.class); // 通過insert，保存一個對象
petsRepository.save(petsPO);
doctorRepository.save(new Doctor(3,"Family2","doctor")); int num = 1/0;
}1234567891011121314151617復(fù)制代碼類型：[java]執(zhí)行代碼，在postman中添加請求：
得到報錯后，查看數(shù)據(jù)庫。
第一個數(shù)據(jù)庫沒有數(shù)據(jù)傳入。
第二個數(shù)據(jù)庫有數(shù)據(jù)傳入。 這是因?yàn)閿?shù)據(jù)庫事物不能跨鏈接，數(shù)據(jù)源更不能跨庫。如果出現(xiàn)了上述操作那這個事務(wù)就變成了分布式事務(wù)，需要一個統(tǒng)一協(xié)調(diào)的管理器。下面讓我們來實(shí)現(xiàn)JPA+atomikos實(shí)現(xiàn)分布式事務(wù)。 首先引入maven依賴： <dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jta-atomikos</artifactId> </dependency>1234復(fù)制代碼類型：[java] 之后改寫.yml文件： spring: jackson: date-format: yyyy-MM-dd HH:mm:ss time-zone: GMT+8 datasource: family: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/Family?useUnicode=true&characterEncoding=utf-8&useSSL=false username: root password: 123456 family2: driver-class-name: com.mysql.cj.jdbc.Driver url: jdbc:mysql://localhost:3306/Family2?useUnicode=true&characterEncoding=utf-8&useSSL=false username: root password: 123456 # jta表示分布式事物 jta: atomikos: datasource: # 數(shù)據(jù)池最大連接數(shù) max-pool-size: 30 # 超出設(shè)定時間拋出異常 borrow-connection-timeout: 100 connectionfactory: max-pool-size: 30 borrow-connection-timeout: 10012345678910111213141516171819202122232425262728復(fù)制代碼類型：[java] 注：將jdbc-url還原成url 在config文件下創(chuàng)建AtomikosJtaPlatform.java，這部分的代碼為固定代碼。 package com.javafamily.familydemo.config;import org.hibernate.engine.transaction.jta.platform.internal.AbstractJtaPlatform;import javax.transaction.TransactionManager;import javax.transaction.UserTransaction;public class AtomikosJtaPlatform extends AbstractJtaPlatform { private static final long serialVersionUID = 1L; static TransactionManager transactionManager; static UserTransaction transaction; @Override
protected TransactionManager locateTransactionManager() { return transactionManager;
} @Override
protected UserTransaction locateUserTransaction() { return transaction;
}
}12345678910111213141516171819202122232425復(fù)制代碼類型：[java]再來進(jìn)行事物管理器配置。在config文件夾下創(chuàng)建JPAAtomikosTransactionConfig.java: package com.javafamily.familydemo.config;import com.atomikos.icatch.jta.UserTransactionImp;import com.atomikos.icatch.jta.UserTransactionManager;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.ComponentScan;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.DependsOn;import org.springframework.context.support.PropertySourcesPlaceholderConfigurer;import org.springframework.orm.jpa.JpaVendorAdapter;import org.springframework.orm.jpa.vendor.Database;import org.springframework.orm.jpa.vendor.HibernateJpaVendorAdapter;import org.springframework.transaction.PlatformTransactionManager;import org.springframework.transaction.annotation.EnableTransactionManagement;import org.springframework.transaction.jta.JtaTransactionManager;import javax.transaction.TransactionManager;import javax.transaction.UserTransaction;@Configuration@ComponentScan@EnableTransactionManagementpublic class JPAAtomikosTransactionConfig { @Bean
public PropertySourcesPlaceholderConfigurer propertySourcesPlaceholderConfigurer() { return new PropertySourcesPlaceholderConfigurer();
} // JPA特性
@Bean
public JpaVendorAdapter jpaVendorAdapter() {
HibernateJpaVendorAdapter hibernateJpaVendorAdapter = new HibernateJpaVendorAdapter();
hibernateJpaVendorAdapter.setShowSql(true);
hibernateJpaVendorAdapter.setGenerateDdl(true);
hibernateJpaVendorAdapter.setDatabase(Database.MYSQL); return hibernateJpaVendorAdapter;
} @Bean(name = "userTransaction")
public UserTransaction userTransaction() throws Throwable {
UserTransactionImp userTransactionImp = new UserTransactionImp();
userTransactionImp.setTransactionTimeout(5000); return userTransactionImp;
} @Bean(name = "atomikosTransactionManager", initMethod = "init", destroyMethod = "close")
public TransactionManager atomikosTransactionManager() throws Throwable {
UserTransactionManager userTransactionManager = new UserTransactionManager();
userTransactionManager.setForceShutdown(false);
AtomikosJtaPlatform.transactionManager = userTransactionManager; return userTransactionManager;
} @Bean(name = "transactionManager")
@DependsOn({"userTransaction", "atomikosTransactionManager"})
public PlatformTransactionManager transactionManager() throws Throwable {
UserTransaction userTransaction = userTransaction();
AtomikosJtaPlatform.transaction = userTransaction;
TransactionManager atomikosTransactionManager = atomikosTransactionManager(); return new JtaTransactionManager(userTransaction, atomikosTransactionManager);
}
}12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364復(fù)制代碼類型：[java]設(shè)置第一個數(shù)據(jù)庫Family的數(shù)據(jù)源和實(shí)體掃描管理： package com.javafamily.familydemo.config;import com.mysql.cj.jdbc.MysqlXADataSource;import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.jta.atomikos.AtomikosDataSourceBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.DependsOn;import org.springframework.context.annotation.Primary;import org.springframework.data.jpa.repository.config.EnableJpaRepositories;import org.springframework.orm.jpa.JpaVendorAdapter;import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import javax.annotation.Resource;import javax.sql.DataSource;import java.sql.SQLException;import java.util.HashMap;@Configuration@DependsOn("transactionManager")@EnableJpaRepositories(basePackages = "com.javafamily.familydemo.dao.db",
entityManagerFactoryRef = "familyEntityManager",
transactionManagerRef = "transactionManager")public class JPAFamilyConfig { @Resource
private JpaVendorAdapter jpaVendorAdapter; @Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.family")
public DataSourceProperties familyDataSourceProperties() { return new DataSourceProperties();
} @Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.family")
public DataSource familyDataSource() throws SQLException {
MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
mysqlXaDataSource.setUrl(familyDataSourceProperties().getUrl());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
mysqlXaDataSource.setPassword(familyDataSourceProperties().getPassword());
mysqlXaDataSource.setUser(familyDataSourceProperties().getUsername());
AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
xaDataSource.setXaDataSource(mysqlXaDataSource);
xaDataSource.setUniqueResourceName("family");
xaDataSource.setBorrowConnectionTimeout(60);
xaDataSource.setMaxPoolSize(20); return xaDataSource;
} @Primary
@Bean
@DependsOn("transactionManager")
public LocalContainerEntityManagerFactoryBean familyEntityManager() throws Throwable {
HashMap<String, Object> properties = new HashMap<String, Object>();
properties.put("hibernate.transaction.jta.platform", AtomikosJtaPlatform.class.getName());
properties.put("javax.persistence.transactionType", "JTA");
LocalContainerEntityManagerFactoryBean entityManager = new LocalContainerEntityManagerFactoryBean();
entityManager.setJtaDataSource(familyDataSource());
entityManager.setJpaVendorAdapter(jpaVendorAdapter); //這里要修改成主數(shù)據(jù)源的掃描包
entityManager.setPackagesToScan("com.javafamily.familydemo.dao.db");
entityManager.setPersistenceUnitName("familyPersistenceUnit");
entityManager.setJpaPropertyMap(properties); return entityManager;
}
}12345678910111213141516171819202122232425262728293031323334353637383940414243444546474849505152535455565758596061626364656667686970復(fù)制代碼類型：[java]設(shè)置第二個數(shù)據(jù)庫Family的數(shù)據(jù)源和實(shí)體掃描管理： package com.javafamily.familydemo.config;import com.mysql.cj.jdbc.MysqlXADataSource;import org.springframework.boot.autoconfigure.jdbc.DataSourceProperties;import org.springframework.boot.context.properties.ConfigurationProperties;import org.springframework.boot.jta.atomikos.AtomikosDataSourceBean;import org.springframework.context.annotation.Bean;import org.springframework.context.annotation.Configuration;import org.springframework.context.annotation.DependsOn;import org.springframework.data.jpa.repository.config.EnableJpaRepositories;import org.springframework.orm.jpa.JpaVendorAdapter;import org.springframework.orm.jpa.LocalContainerEntityManagerFactoryBean;import javax.annotation.Resource;import javax.sql.DataSource;import java.sql.SQLException;import java.util.HashMap;@Configuration@DependsOn("transactionManager")@EnableJpaRepositories(basePackages = "com.javafamily.familydemo.dao.db2",
entityManagerFactoryRef = "family2EntityManager",
transactionManagerRef = "transactionManager")public class JPAFamily2Config { @Resource
private JpaVendorAdapter jpaVendorAdapter; @Bean
@ConfigurationProperties(prefix = "spring.datasource.family2") //注意這里
public DataSourceProperties family2DataSourceProperties() { return new DataSourceProperties();
} // @Bean(name = "family2DataSource", initMethod = "init", destroyMethod = "close")
@Bean
@ConfigurationProperties(prefix = "spring.datasource.family2")
public DataSource family2DataSource() throws SQLException {
MysqlXADataSource mysqlXaDataSource = new MysqlXADataSource();
mysqlXaDataSource.setUrl(family2DataSourceProperties().getUrl());
mysqlXaDataSource.setPinGlobalTxToPhysicalConnection(true);
mysqlXaDataSource.setPassword(family2DataSourceProperties().getPassword());
mysqlXaDataSource.setUser(family2DataSourceProperties().getUsername());
AtomikosDataSourceBean xaDataSource = new AtomikosDataSourceBean();
xaDataSource.setXaDataSource(mysqlXaDataSource);
xaDataSource.setUniqueResourceName("family2");
xaDataSource.setBorrowConnectionTimeout(60);
xaDataSource.setMaxPoolSize(20); return xaDataSource;
} @Bean
@DependsOn("transactionManager")
public LocalContainerEntityManagerFactoryBean family2EntityManager() throws Throwable {
HashMap<String, Object> properties = new HashMap<String, Object>();
properties.put("hibernate.transaction.jta.platform", AtomikosJtaPlatform.class.getName());
properties.put("javax.persistence.transactionType", "JTA");
LocalContainerEntityManagerFactoryBean entityManager = new LocalContainerEntityManagerFactoryBean();
entityManager.setJtaDataSource(family2DataSource());
entityManager.setJpaVendorAdapter(jpaVendorAdapter); //這里要修改成主數(shù)據(jù)源的掃描包
entityManager.setPackagesToScan("com.javafamily.familydemo.dao.db2");
entityManager.setPersistenceUnitName("family2PersistenceUnit");
entityManager.setJpaPropertyMap(properties); return entityManager;
}
}123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869復(fù)制代碼類型：[java]通過以上代碼我們會發(fā)現(xiàn)，除了事物管理器只有一個以外，其他都是兩個。不同的數(shù)據(jù)源通過同一個事物管理器實(shí)現(xiàn)了分布式事務(wù)。 這時我們再次執(zhí)行代碼，會發(fā)現(xiàn)報錯之后兩個數(shù)據(jù)庫都沒有數(shù)據(jù)庫插入。
當(dāng)把錯誤代碼去除后（intnum=1/0;）再次執(zhí)行，兩個數(shù)據(jù)庫的數(shù)據(jù)均已插入。
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