In previous tutorials in this series , We have shown you how to use the three most commonly used data access methods ：

• JdbcTemplate
• Spring Data JPA
• MyBatis

Next, we will be divided into three parts to introduce the three ways of data access , When we need multiple data sources , Configuration instructions for how to use .

Add configuration for multiple data sources

First in Spring Boot Configuration file for application.properties Set up two database configurations that you want to link , Such as this ：

spring.datasource.primary.jdbc-url=jdbc:mysql://localhost:3306/test1
spring.datasource.primary.username=root
spring.datasource.primary.password=123456
spring.datasource.primary.driver-class-name=com.mysql.cj.jdbc.Driver
spring.datasource.secondary.jdbc-url=jdbc:mysql://localhost:3306/test2
spring.datasource.secondary.username=root
spring.datasource.secondary.password=123456
spring.datasource.secondary.driver-class-name=com.mysql.cj.jdbc.Driver

Explanation and attention ：

1. Multi source data configuration , The difference with a single data source is that spring.datasource After that, set a data source name primary and secondary To distinguish between different data source configurations , This prefix will be used in subsequent initialization of the data source .
2. Data source connection configuration 2.x and 1.x There is a difference between the configuration items of ：2.x Use spring.datasource.secondary.jdbc-url, and 1.x Version USES spring.datasource.secondary.url. If this error occurs during configuration java.lang.IllegalArgumentException: jdbcUrl is required with driverClassName., So it’s the configuration item .

Related reading ：Spring Boot 1.x Basic course ： Multi data source configuration

Initialize the data source with JdbcTemplate

After completing the configuration information of multiple data sources , Let’s create a configuration class to load the configuration information , Initialize the data source , And initialize each data source with JdbcTemplate. You just need to Spring Boot Add the following configuration class under the application to complete ！

@Configuration
public class DataSourceConfiguration {

@Primary
@Bean
@ConfigurationProperties(prefix = "spring.datasource.primary")
public DataSource primaryDataSource() {

return DataSourceBuilder.create().build();
}
@Bean
@ConfigurationProperties(prefix = "spring.datasource.secondary")
public DataSource secondaryDataSource() {

return DataSourceBuilder.create().build();
}
@Bean
public JdbcTemplate primaryJdbcTemplate(@Qualifier("primaryDataSource") DataSource primaryDataSource) {

return new JdbcTemplate(primaryDataSource);
}
@Bean
public JdbcTemplate secondaryJdbcTemplate(@Qualifier("secondaryDataSource") DataSource secondaryDataSource) {

return new JdbcTemplate(secondaryDataSource);
}
}

Explanation and attention ：

1. The first two Bean It’s the creation of data sources , adopt @ConfigurationProperties You can know that the two data sources have loaded spring.datasource.primary.* and spring.datasource.secondary.* Configuration of .
2. @Primary The annotation specifies the master data source , When we don’t specifically specify which data source , You’ll use this Bean
3. The latter two Bean It’s for each data source JdbcTemplate. You can see these two JdbcTemplate At the time of creation , They injected primaryDataSource Data sources and secondaryDataSource data source

Test it

After finishing the above , We can write a test class to test whether the above multi data source configuration is correct , Like the following ：

@RunWith(SpringRunner.class)
@SpringBootTest
public class Chapter37ApplicationTests {

@Autowired
protected JdbcTemplate primaryJdbcTemplate;
@Autowired
protected JdbcTemplate secondaryJdbcTemplate;
@Before
public void setUp() {

primaryJdbcTemplate.update("DELETE FROM USER ");
secondaryJdbcTemplate.update("DELETE FROM USER ");
}
@Test
public void test() throws Exception {

// Insert... Into the first data source 2 Data 
primaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "aaa", 20);
primaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "bbb", 30);
// Insert... Into the second data source 1 Data , If you insert the first data source , The primary key conflict will be reported 
secondaryJdbcTemplate.update("insert into user(name,age) values(?, ?)", "ccc", 20);
// Check to see if there is any in the first data source 2 Data , Verify that the insertion was successful 
Assert.assertEquals("2", primaryJdbcTemplate.queryForObject("select count(1) from user", String.class));
// Check to see if there is any in the first data source 1 Data , Verify that the insertion was successful 
Assert.assertEquals("1", secondaryJdbcTemplate.queryForObject("select count(1) from user", String.class));
}
}

Explanation and attention ：

1. Maybe here you ask , There are two JdbcTemplate, Why not @Qualifier Appoint ？ Here’s a little bit of knowledge , When we don’t specify , The name of the parameter is used to find Bean, If there is, inject .
2. these two items. JdbcTemplate At the time of creation , We didn’t name it either , How they match ？ Here is also a little bit of knowledge , When we create Bean When , By default, the method name is used as Bean The name of , So here’s the corresponding . Readers might as well look back to see if the two names are identical ？

Code example

For an example of this article, see the following in the warehouse chapter3-7 Catalog ：

• Github：https://github.com/dyc87112/SpringBoot-Learning/
• Gitee：https://gitee.com/didispace/SpringBoot-Learning/

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This article was first published in ：Spring Boot 2.x Basic course ：JdbcTemplate Multi data source configuration for , Reprint please indicate the source . This series of topics can be Click to learn for free ！