SpringBoot创建项目非常方便，而且进行数据访问抛弃了很多繁琐的配置，我前面写的系列博文中，有教大家如何使用SpringBoot进行数据访问，里面谈到了整合JDBC、MyBatis以及JPA。我自己实际开发中，如果没有什么要求限制的话，比较习惯使用JPA进行数据访问，所以在这里，我专门编写一篇博文，来教如何使用SpringBoot整合JPA，进行多数据库的配置
准备
开始之前呢，我们需要先创建项目啦，创建项目使用的是Idea的Spring Initializr进行创建，选择SpringBoot场景的时候，勾选Web、Spring Data JPA、MySQL Driver三个就可以了，如下，然后项目创建成功。
主配置文件
如果我们只是进行一个数据库的访问，我们只需要对数据库进行简单的配置，提供相应账号和密码就可以了，不过多个数据库也不是很麻烦，也就是相当于多一份配置内容出来而已，所有配置内容如下
application.properties
#数据库统一配置
spring.jpa.hibernate.ddl-auto=update
spring.jpa.show-sql=true
spring.jpa.properties.hibernate.hbm2ddl.auto=update
spring.jpa.properties.hibernate.dialect=org.hibernate.dialect.MySQL5InnoDBDialect
spring.jpa.properties.hibernate.format_sql=true
#主数据库
spring.datasource.primary.jdbc-url=jdbc:mysql://localhost/ubiquity?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.jdbc.Driver
#副数据库
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost/ubiquity_vote?serverTimezone=UTC&useUnicode=true&characterEncoding=utf-8&useSSL=true
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.jdbc.Driver
配置类
我们都知道，我们在配置文件中写的配置，需要我们通过配置类的注入，覆盖掉默认的配置，这样才会生效，所以，我们能够想到，既然是需要使用多个数据库，对应的自然会有多个数据库的相关配置类（这篇博文的示例中，我使用两个数据库，所以有两个数据配置类）
我们知道，我们首先在只配置类中编写两个配置数据库的组件，然后分别其组件名，具体内容如下。
DataSourceConfig.java
package com.dbc.ubiquity.Config;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateProperties;
import org.springframework.boot.autoconfigure.orm.jpa.HibernateSettings;
import org.springframework.boot.autoconfigure.orm.jpa.JpaProperties;
import org.springframework.boot.context.properties.ConfigurationProperties;
import org.springframework.boot.jdbc.DataSourceBuilder;
import org.springframework.context.annotation.Bean;
import org.springframework.context.annotation.Configuration;
import org.springframework.context.annotation.Primary;
import javax.sql.DataSource;
import java.util.Map;
@Configuration
public class DataSourceConfig {
@Autowired
private JpaProperties jpaProperties;
@Autowired
private HibernateProperties hibernateProperties;
@Bean(name = "primaryDataSource")
@Primary
@ConfigurationProperties("spring.datasource.primary")
public DataSource firstDataSource(){
return DataSourceBuilder.create().build();
}
@Bean(name = "secondaryDataSource")
@ConfigurationProperties("spring.datasource.secondary")
public DataSource secondDataSource(){
return DataSourceBuilder.create().build();
}
@Bean(name = "vendorProperties")
public Map<String, Object> getVendorProperties() {
return hibernateProperties.determineHibernateProperties(
jpaProperties.getProperties(), new HibernateSettings());
}
}
然后我们编写了针对两个数据库的配置类，里面的代码非常的相似，相信你敲了一遍之后，能够感悟到点什么。
PrimaryConfig.java
package com.dbc.ubiquity.Config;
import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;
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.persistence.EntityManager;
import javax.sql.DataSource;
import java.util.Map;
@Configuration
@EnableTransactionManagement
@EnableJpaRepositories(
entityManagerFactoryRef = "entityManagerFactoryPrimary",
transactionManagerRef = "transactionManagerPrimary",
basePackages = {"com.dbc.ubiquity.Repository.Primary"}//Dao层的位置
)
public class PrimaryConfig {
@Autowired
@Qualifier("primaryDataSource")
private DataSource primaryDataSource;
@Autowired
@Qualifier("vendorProperties")
private Map<String, Object> vendorProperties;
@Bean(name = "entityManagerFactoryPrimary")
@Primary
public LocalContainerEntityManagerFactoryBean entityManagerFactoryPrimary(EntityManagerFactoryBuilder builder){
return builder
.dataSource(primaryDataSource)
.properties(vendorProperties)
.packages("com.dbc.ubiquity.Model.Primary")//实体类的位置
.persistenceUnit("primaryPersistenceUnit")
.build();
}
@Bean(name = "entityManagerPrimary")
@Primary
public EntityManager entityManager(EntityManagerFactoryBuilder builder){
return entityManagerFactoryPrimary(builder).getObject().createEntityManager();
}
@Bean(name = "transactionManagerPrimary")
@Primary
PlatformTransactionManager transactionManagerPrimary(EntityManagerFactoryBuilder builder){
return new JpaTransactionManager(entityManagerFactoryPrimary(builder).getObject());
}
}
实体类
首先我先把实体类的目录结构放在这，方便后面编写，然后说道实体类的创建，这里可以使用Idea帮我们逆向生成实体类，也就是依照在数据库中已经创建好的数据库表，自动生成实体类，不过这种方式生成出来的实体类，不符合现在编写JPA的序列化格式，生成出来的还是要增改（当然啦，你可以直接去更改实体类生成的模板，没错是可以改的，具体怎么改我这里就不赘述了，自己百度就可以知道），我就来说手动创建，手动创建的好处就是能够对知识点进行更加深入的掌握，当然啦，敲起来比较费时间。
User.java
package com.dbc.ubiquity.Entity.Primary;
import javax.persistence.*;
import java.io.Serializable;
@Entity
@Table(name = "USER", schema = "ubiquity", catalog = "")
public class User implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long id;
@Column(nullable = false, unique = true)
private String userName;
@Column(nullable = false)
private String passWord;
@Column(nullable = false, unique = true)
private String email;
@Column(nullable = true, unique = true)
private String nickName;
@Column(nullable = false)
private String regTime;
public User() {
}
public User(String userName, String passWord, String email, String nickName, String regTime) {
this.userName = userName;
this.passWord = passWord;
this.email = email;
this.nickName = nickName;
this.regTime = regTime;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getNickName() {
return nickName;
}
public void setNickName(String nickName) {
this.nickName = nickName;
}
public String getRegTime() {
return regTime;
}
public void setRegTime(String regTime) {
this.regTime = regTime;
}
}
Userq.java
package com.dbc.ubiquity.Entity.Secondary;
import javax.persistence.*;
import java.io.Serializable;
@Entity
@Table(name = "USERQ", schema = "ubiquity_vote", catalog = "")
public class Userq implements Serializable {
private static final long serialVersionUID = 1L;
@Id
@GeneratedValue(strategy = GenerationType.IDENTITY)
@Column(name = "id")
private long id;
@Column(nullable = false, unique = true)
private String userName;
@Column(nullable = false)
private String passWord;
@Column(nullable = false, unique = true)
private String email;
@Column(nullable = true, unique = true)
private String nickName;
@Column(nullable = false)
private String regTime;
public Userq() {
}
public Userq(String userName, String passWord, String email, String nickName, String regTime) {
this.userName = userName;
this.passWord = passWord;
this.email = email;
this.nickName = nickName;
this.regTime = regTime;
}
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
public String getUserName() {
return userName;
}
public void setUserName(String userName) {
this.userName = userName;
}
public String getPassWord() {
return passWord;
}
public void setPassWord(String passWord) {
this.passWord = passWord;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getNickName() {
return nickName;
}
public void setNickName(String nickName) {
this.nickName = nickName;
}
public String getRegTime() {
return regTime;
}
public void setRegTime(String regTime) {
this.regTime = regTime;
}
}
写到这里，就要说一下前面主配置文件里面的一些配置是什么了，如下
它还有其他属性，如下：
- ddl-auto:create----每次运行该程序，没有表格会新建表格，表内有数据会清空
- ddl-auto:create-drop----每次程序结束的时候会清空表
- ddl-auto:update----每次运行程序，没有表格会新建表格，表内有数据不会清空，只会更新
- ddl-auto:validate----运行程序会校验数据与数据库的字段类型是否相同，不同会报错
Dao层
package com.dbc.ubiquity.Repository.Primary;
import com.dbc.ubiquity.Entity.Primary.User;
import org.springframework.data.jpa.repository.JpaRepository;
public interface UserPrimaryPository extends JpaRepository<User, Long> {
User findById(long id);
User findByUserName(String userName);
User findByUserNameOrEmail(String username, String email);
}
package com.dbc.ubiquity.Repository.Secondary;
import com.dbc.ubiquity.Entity.Secondary.Userq;
import org.springframework.data.jpa.repository.JpaRepository;
public interface UserSecondaryPository extends JpaRepository<Userq, Long> {
Userq findById(long id);
Userq findByUserName(String userName);
Userq findByUserNameOrEmail(String username, String email);
}
测试
到此，我们的多数据库配置流程到此结束，最后就是测试阶段了，我们来验证一下我们的配置是否有用。测试类的内容如下
package com.dbc.ubiquity;
import com.dbc.ubiquity.Entity.Primary.User;
import com.dbc.ubiquity.Entity.Secondary.Userq;
import com.dbc.ubiquity.Repository.Primary.UserPrimaryPository;
import com.dbc.ubiquity.Repository.Secondary.UserSecondaryPository;
import org.junit.jupiter.api.Test;
import org.springframework.boot.test.context.SpringBootTest;
import javax.annotation.Resource;
import java.text.DateFormat;
import java.util.Date;
@SpringBootTest
class UbiquityApplicationTests {
@Resource
private UserPrimaryPository userPrimaryPository;
@Resource
private UserSecondaryPository userSecondaryPository;
@Test
public void testSave() throws Exception{
Date date = new Date();
DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG);
String formattedDate = dateFormat.format(date);
userPrimaryPository.save(new User("aa", "aa123456","[email protected]", "aa", formattedDate));
userPrimaryPository.save(new User("bb", "bb123456","[email protected]", "bb", formattedDate));
userSecondaryPository.save(new Userq("cc", "cc123456","[email protected]", "cc", formattedDate));
}
@Test
public void testDelete() throws Exception {
userPrimaryPository.deleteAll();
userSecondaryPository.deleteAll();
}
@Test
public void testBaseQuery() {
Date date = new Date();
DateFormat dateFormat = DateFormat.getDateTimeInstance(DateFormat.LONG, DateFormat.LONG);
String formattedDate = dateFormat.format(date);
User user=new User("ff", "ff123456","[email protected]", "ff", formattedDate);
Userq userq=new Userq("ff", "ff123456","[email protected]", "ff", formattedDate);
userPrimaryPository.findAll();
userSecondaryPository.findById(3l);
userSecondaryPository.save(userq);
user.setId(2l);
userPrimaryPository.delete(user);
userPrimaryPository.count();
userSecondaryPository.findById(3l);
}
@Test
void contextLoads() {
}
}
