springboot配置多数据源（JdbcTemplate方式）

在实际开发中可能会遇到需要配置多个数据源的情况，比如：需要使用多个host、需要使用多种数据库（MySql、Oracle、SqlServer…）

如果使用springboot开发，可做如下配置：

Config：

import org.springframework.beans.factory.annotation.Qualifier;
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 org.springframework.jdbc.core.JdbcTemplate;

import javax.sql.DataSource;

@Configuration
public class DataSourceConfig {

@Bean(name = "testDataSource")
@Primary
@Qualifier("testDataSource")
@ConfigurationProperties(prefix="spring.datasource.hikari.mysql")
public DataSource testDataSource() {
return DataSourceBuilder.create().build();
}

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

@Bean(name="testJdbcTemplate")
public JdbcTemplate testJdbcTemplate (
@Qualifier("testDataSource") DataSource testDataSource ) {
return new JdbcTemplate(testDataSource);
}

@Bean(name = "formalJdbcTemplate")
public JdbcTemplate formalJdbcTemplate(
@Qualifier("formalDataSource") DataSource formalDataSource){
return new JdbcTemplate(formalDataSource);
}
}

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配置文件 application.properties

spring.datasource.hikari.mysql.jdbc-url =jdbc:mysql://mysql2.cdqdops.org:3306/standard?useUnicode=true&characterEncoding=utf-8&useSSL=false&allowMultiQueries=true
spring.datasource.hikari.mysql.username = root
spring.datasource.hikari.mysql.password = 123456
spring.datasource.hikari.mysql.driver-class-Name = com.mysql.jdbc.Driver

spring.datasource.formal.mysql.jdbc-url =jdbc:mysql://localhost:3306/test?useUnicode=true&characterEncoding=utf-8&useSSL=false&allowMultiQueries=true
spring.datasource.formal.mysql.username = root
spring.datasource.formal.mysql.password = 1314
spring.datasource.formal.mysql.driver-class-Name = com.mysql.jdbc.Driver
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注意事项
使用多个数据源时，需要添加**@Primary**注解

@Primary：自动装配时当出现多个Bean候选者时，被注解为@Primary的Bean将作为首选者

当然,primary意味着"主要的",类似与SQL语句中的"primary key",有且只能有一个

开发时,别人将注释掉的代码恢复,出现了多个"@Primary",就导致了如下错误:

[root@app4 logs]# tail stdout.log
Caused by: org.springframework.beans.factory.NoUniqueBeanDefinitionException: No qualifying bean of type 'javax.sql.DataSource' available: more than one 'primary' bean found among candidates: [mysqlDataSource, formalDataSource, sqlServerDataSource]
at org.springframework.beans.factory.support.DefaultListableBeanFactory.determinePrimaryCandidate(DefaultListableBeanFactory.java:1381)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.determineAutowireCandidate(DefaultListableBeanFactory.java:1341)
at org.springframework.beans.factory.support.DefaultListableBeanFactory.doResolveDependency(DefaultListableBeanFactory.java:1110)
at org.springframework.beans.factory.support.DefaultListableBeanFactory$DependencyObjectProvider.getIfUnique(DefaultListableBeanFactory.java:1728)
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializerInvoker.getDataSourceInitializer(DataSourceInitializerInvoker.java:100)
at org.springframework.boot.autoconfigure.jdbc.DataSourceInitializerInvoker.afterPropertiesSet(DataSourceInitializerInvoker.java:62)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.invokeInitMethods(AbstractAutowireCapableBeanFactory.java:1758)
at org.springframework.beans.factory.support.AbstractAutowireCapableBeanFactory.initializeBean(AbstractAutowireCapableBeanFactory.java:1695)
... 32 common frames omitted
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