1.
spring-boot-starter-jdbc 里引入了 hikari 依赖:
<dependency>
<groupId>com.zaxxer</groupId>
<artifactId>HikariCP</artifactId>
<version>5.1.0</version>
<scope>compile</scope>
</dependency>
2. spring-boot-starter 里引入 spring-boot-autoconfigure 依赖.
autoconfigure的META-INF/spring/org.springframework.boot.autoconfigure.AutoConfiguration.imports 该类正式开始引入了`DataSourceConfiguration`
org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfigurationpackage org.springframework.boot.autoconfigure.jdbc;
@AutoConfiguration(before = SqlInitializationAutoConfiguration.class)
@ConditionalOnClass({ DataSource.class, EmbeddedDatabaseType.class })
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory")
@EnableConfigurationProperties(DataSourceProperties.class)
//@ConfigurationProperties(prefix = "spring.datasource")
//声明 DataSourceProperties 类是一个 @ConfigurationProperties 类，并将其注册为 Spring 容器中的 Bean。
@Import({ DataSourcePoolMetadataProvidersConfiguration.class, DataSourceCheckpointRestoreConfiguration.class })
public class DataSourceAutoConfiguration {
@Configuration(proxyBeanMethods = false)
@Conditional(EmbeddedDatabaseCondition.class)
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
@Import(EmbeddedDataSourceConfiguration.class)
protected static class EmbeddedDatabaseConfiguration {
}
@Configuration(proxyBeanMethods = false)
@Conditional(PooledDataSourceCondition.class)
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
//手动定义DataSource时不再加载这个配置类.如自定义sqlite的DataSource配置时.
@Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class,
DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class })
//导入其他配置类或组件到当前上下文中。
//这些类分别对应不同的数据源实现（如 HikariCP、Tomcat JDBC Pool、Dbcp2 等）。
//Spring Boot 会根据运行时条件（如依赖库的存在与否）选择合适的实现来加载数据源。
protected static class PooledDataSourceConfiguration {
@Bean
@ConditionalOnMissingBean(JdbcConnectionDetails.class)
PropertiesJdbcConnectionDetails jdbcConnectionDetails(DataSourceProperties properties) {
//将 DataSourceProperties 对象封装为 PropertiesJdbcConnectionDetails 实例并返回。
//PropertiesJdbcConnectionDetails 是一个辅助类，通常用于提取数据库连接信息（如 URL、用户名、密码等）。
return new PropertiesJdbcConnectionDetails(properties);
}
}
/**
* {@link AnyNestedCondition} that checks that either {@code spring.datasource.type}
* is set or {@link PooledDataSourceAvailableCondition} applies.
*/
static class PooledDataSourceCondition extends AnyNestedCondition {
PooledDataSourceCondition() {
super(ConfigurationPhase.PARSE_CONFIGURATION);
}
@ConditionalOnProperty(prefix = "spring.datasource", name = "type")
static class ExplicitType {
}
@Conditional(PooledDataSourceAvailableCondition.class)
static class PooledDataSourceAvailable {
}
}
/**
* {@link Condition} to test if a supported connection pool is available.
*/
static class PooledDataSourceAvailableCondition extends SpringBootCondition {
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
ConditionMessage.Builder message = ConditionMessage.forCondition("PooledDataSource");
if (DataSourceBuilder.findType(context.getClassLoader()) != null) {
return ConditionOutcome.match(message.foundExactly("supported DataSource"));
}
return ConditionOutcome.noMatch(message.didNotFind("supported DataSource").atAll());
}
}
/**
* {@link Condition} to detect when an embedded {@link DataSource} type can be used.
* If a pooled {@link DataSource} is available, it will always be preferred to an
* {@code EmbeddedDatabase}.
*/
static class EmbeddedDatabaseCondition extends SpringBootCondition {
private static final String DATASOURCE_URL_PROPERTY = "spring.datasource.url";
private final SpringBootCondition pooledCondition = new PooledDataSourceCondition();
@Override
public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) {
ConditionMessage.Builder message = ConditionMessage.forCondition("EmbeddedDataSource");
if (hasDataSourceUrlProperty(context)) {
return ConditionOutcome.noMatch(message.because(DATASOURCE_URL_PROPERTY + " is set"));
}
if (anyMatches(context, metadata, this.pooledCondition)) {
return ConditionOutcome.noMatch(message.foundExactly("supported pooled data source"));
}
EmbeddedDatabaseType type = EmbeddedDatabaseConnection.get(context.getClassLoader()).getType();
if (type == null) {
return ConditionOutcome.noMatch(message.didNotFind("embedded database").atAll());
}
return ConditionOutcome.match(message.found("embedded database").items(type));
}
private boolean hasDataSourceUrlProperty(ConditionContext context) {
Environment environment = context.getEnvironment();
if (environment.containsProperty(DATASOURCE_URL_PROPERTY)) {
try {
return StringUtils.hasText(environment.getProperty(DATASOURCE_URL_PROPERTY));
}
catch (IllegalArgumentException ex) {
// NOTE: This should be PlaceholderResolutionException
// Ignore unresolvable placeholder errors
}
}
return false;
}
}
}
### org.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration
package org.springframework.boot.autoconfigure.jdbc;
abstract class DataSourceConfiguration {
@Configuration(proxyBeanMethods = false)
@ConditionalOnClass(HikariDataSource.class)
@ConditionalOnMissingBean(DataSource.class)
@ConditionalOnProperty(name = "spring.datasource.type", havingValue = "com.zaxxer.hikari.HikariDataSource",
matchIfMissing = true)
//如果显式设置了 spring.datasource.type=com.zaxxer.hikari.HikariDataSource,没有也行 `matchIfMissing = true`
static class Hikari {
@Bean
static HikariJdbcConnectionDetailsBeanPostProcessor jdbcConnectionDetailsHikariBeanPostProcessor(
ObjectProvider<JdbcConnectionDetails> connectionDetailsProvider) {
return new HikariJdbcConnectionDetailsBeanPostProcessor(connectionDetailsProvider);
}
@Bean
@ConfigurationProperties(prefix = "spring.datasource.hikari")
//这里将 配置文件中 hukari的配置 自动包装到 HikariDataSource 里
//这里就正式定义全局的 DataSource bean啦
HikariDataSource dataSource(DataSourceProperties properties, JdbcConnectionDetails connectionDetails) {
HikariDataSource dataSource = createDataSource(connectionDetails, HikariDataSource.class,
properties.getClassLoader());
if (StringUtils.hasText(properties.getName())) {
dataSource.setPoolName(properties.getName());
}
return dataSource;
}
}
......
}