SpringBoot项目中的多数据源支持的方法

1.概述

项目中经常会遇到一个应用需要访问多个数据源的情况，本文介绍在springboot项目中利用springdatajpa技术如何支持多个数据库的数据源。

具体的代码参照该

2.建立实体类（entity）

首先，我们创建两个简单的实体类，分别属于两个不同的数据源，用于演示多数据源数据的保存和查询。

test实体类：

package com.example.demo.test.data;

import javax.persistence.entity;
import javax.persistence.id;
import javax.persistence.table;

@entity
@table(name = "test")
public class test {

  @id
  private integer id;

  public test(){

  }

  public integer getid() {
    return this.id;
  }

  public void setid(integer id){
    this.id = id;
  }
}

other实体类：

package com.example.demo.other.data;

import javax.persistence.entity;
import javax.persistence.id;
import javax.persistence.table;

@entity
@table(name = "other")
public class other {

  @id
  private integer id;

  public integer getid() {
    return this.id;
  }

  public void setid(integer id){
    this.id = id;
  }
}

需要注意的是，这两个实体类分属于不同的package，这一点极为重要，spring会根据实体类所属的package来决定用那一个数据源进行操作。

3.建立repository

分别建立两个实体类对应的repository，用于进行数据操作。

testrepository:

package com.example.demo.test.data;

import org.springframework.data.jpa.repository.jparepository;

public interface testrepository extends jparepository<test, integer> {
}

otherrepository:

package com.example.demo.other.data;

import org.springframework.data.jpa.repository.jparepository;

public interface otherrepository extends jparepository<other, integer> {
}

得益于spring-data-jpa优秀的封装，我们只需创建一个接口，就拥有了对实体类的操作能力。

3.对多数据源进行配置

分别对test和other两个实体类配置对应的数据源。配置的内容主要包含三个要素：

1. datasource，数据源的连接信息
2. entitymanagerfactory，数据处理
3. transactionmanager，事务管理

test实体类的数据源配置 testdataconfig：

package com.example.demo.config;

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.beans.factory.annotation.qualifier;
import org.springframework.boot.autoconfigure.jdbc.datasourcebuilder;
import org.springframework.boot.autoconfigure.orm.jpa.jpaproperties;
import org.springframework.boot.context.properties.configurationproperties;
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.entitymanagerfactory;
import javax.sql.datasource;

@configuration
@enabletransactionmanagement
@enablejparepositories(
    entitymanagerfactoryref = "entitymanagerfactory",
    basepackages = {"com.example.demo.test.data"}
)
public class testdataconfig {

  @autowired
  private jpaproperties jpaproperties;

  @primary
  @bean(name = "datasource")
  @configurationproperties(prefix = "spring.datasource")
  public datasource datasource() {
    return datasourcebuilder.create().build();
  }

  @primary
  @bean(name = "entitymanagerfactory")
  public localcontainerentitymanagerfactorybean entitymanagerfactory(
      entitymanagerfactorybuilder builder,
      @qualifier("datasource") datasource datasource) {
    return builder
        .datasource(datasource)
        .packages("com.example.demo.test.data")
        .properties(jpaproperties.gethibernateproperties(datasource))
        .persistenceunit("test")
        .build();
  }

  @primary
  @bean(name = "transactionmanager")
  public platformtransactionmanager transactionmanager(
      @qualifier("entitymanagerfactory") entitymanagerfactory entitymanagerfactory) {
    return new jpatransactionmanager(entitymanagerfactory);
  }

}

代码中的primary注解表示这是默认数据源。

other实体类的数据源配置 otherdataconfig：

package com.example.demo.config;

import org.springframework.beans.factory.annotation.autowired;
import org.springframework.beans.factory.annotation.qualifier;
import org.springframework.boot.autoconfigure.jdbc.datasourcebuilder;
import org.springframework.boot.autoconfigure.orm.jpa.jpaproperties;
import org.springframework.boot.context.properties.configurationproperties;
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.persistence.entitymanagerfactory;
import javax.sql.datasource;

@configuration
@enabletransactionmanagement
@enablejparepositories(
    entitymanagerfactoryref = "otherentitymanagerfactory",
    transactionmanagerref = "othertransactionmanager",
    basepackages = {"com.example.demo.other.data"}
)
public class otherdataconfig {

  @autowired
  private jpaproperties jpaproperties;

  @bean(name = "otherdatasource")
  @configurationproperties(prefix = "other.datasource")
  public datasource otherdatasource() {
    return datasourcebuilder.create().build();
  }

  @bean(name = "otherentitymanagerfactory")
  public localcontainerentitymanagerfactorybean otherentitymanagerfactory(
      entitymanagerfactorybuilder builder,
      @qualifier("otherdatasource") datasource otherdatasource) {
    return builder
        .datasource(otherdatasource)
        .packages("com.example.demo.other.data")
        .properties(jpaproperties.gethibernateproperties(otherdatasource))
        .persistenceunit("other")
        .build();
  }

  @bean(name = "othertransactionmanager")
  public platformtransactionmanager othertransactionmanager(
      @qualifier("otherentitymanagerfactory") entitymanagerfactory otherentitymanagerfactory) {
    return new jpatransactionmanager(otherentitymanagerfactory);
  }

}

3.数据操作

我们创建一个service类testservice来分别对两个数据源进行数据的操作。

package com.example.demo.service;

import com.example.demo.other.data.other;
import com.example.demo.other.data.otherrepository;
import com.example.demo.test.data.test;
import com.example.demo.test.data.testrepository;
import org.springframework.beans.factory.annotation.autowired;
import org.springframework.beans.factory.annotation.value;
import org.springframework.stereotype.component;

@component
public class testservice {

  @autowired
  private testrepository testrepository;

  @autowired
  private otherrepository otherrepository;

  @value("${name:world}")
  private string name;

  public string gethellomessage() {
    test test = new test();
    test.setid(1);
    test = testrepository.save(test);

    other other = new other();
    other.setid(2);
    other = otherrepository.save(other);

    return "hello " + this.name + " : test's value = " + test.getid() + " , other's value = " + other.getid();

  }

}

对test和other分别进行数据插入和读取操作，程序运行后会打印出两个数据源各自的数据。 数据库采用的mysql，连接信息在application.yml进行配置。

spring:
 datasource:
  url: jdbc:mysql://localhost:3306/test?characterencoding=utf-8&usessl=false
  testwhileidle: true
  validationquery: select 1 from dual
  username: test
  password: 11111111
  driverclassname: com.mysql.jdbc.driver
 jpa:
  database: mysql
  show-sql: true
  hibernate:
   show-sql: true
   ddl-auto: create
   naming-strategy: org.hibernate.cfg.improvednamingstrategy
  properties:
   hibernate.dialect: org.hibernate.dialect.mysql5dialect
other:
 datasource:
  url: jdbc:mysql://localhost:3306/other?characterencoding=utf-8&usessl=false
  testwhileidle: true
  validationquery: select 1
  username: other
  password: 11111111
  driverclassname: com.mysql.jdbc.driver
 jpa:
  database: mysql
  show-sql: true
  hibernate:
   show-sql: true
   ddl-auto: create
   naming-strategy: org.hibernate.cfg.improvednamingstrategy
  properties:
   hibernate.dialect: org.hibernate.dialect.mysql5dialect

test实体对应的是主数据源，采用了spring-boot的默认数据源配置项，other实体单独配置数据源连接。具体应该读取哪一段配置内容，是在配置类otherdataconfig中这行代码指定的。

@configurationproperties(prefix = "other.datasource")

本示例需要建立的数据库用户和库可以通过以下命令处理：

create user 'test'@'localhost' identified by '11111111';
grant all privileges on *.* to 'test'@'localhost';
create user 'other'@'localhost' identified by '11111111';
grant all privileges on *.* to 'other'@'localhost';
create database test;
create database other;

4.总结

spring-data-jpa极大的简化了数据库操作，对于多数据源的支持，也只是需要增加一下配置文件和配置类而已。其中的关键内容有3点：

1. 配置文件中数据源的配置
2. 配置类的编写
3. 实体类所在的package必须与配置类中指定的package一致，如otherdataconfig中指定的basepackages = {"com.example.demo.other.data"}

以上就是本文的全部内容，希望对大家的学习有所帮助，也希望大家多多支持。