import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
@PostConstruct
public void initialize() {
	DataSource primaryDataSource = getPrimaryDataSource();
	DataSourcePoolMetadataProvider provider = new DataSourcePoolMetadataProviders(
			this.providers);
	for (Map.Entry<String, DataSource> entry : this.applicationContext
			.getBeansOfType(DataSource.class).entrySet()) {
		String beanName = entry.getKey();
		DataSource bean = entry.getValue();
		String prefix = createPrefix(beanName, bean, bean.equals(primaryDataSource));
		DataSourcePoolMetadata poolMetadata = provider
				.getDataSourcePoolMetadata(bean);
		if (poolMetadata != null) {
			this.metadataByPrefix.put(prefix, poolMetadata);
		}
	}
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
DataSourceMetricsHolder(String dataSourceName, DataSourcePoolMetadata poolMetadata, MeterRegistry registry) {
    connectionObtainTimer = Timer.builder("data.source.connections.wait")
            .tags("pool", dataSourceName)
            .register(registry);

    connectionUsageTimer = Timer.builder("data.source.connections.usage")
            .tags("pool", dataSourceName)
            .register(registry);

    connectionCreatedCounter = Counter.builder("data.source.connections.created")
            .tags("pool", dataSourceName)
            .register(registry);

    connectionFailedCounter = Counter.builder("data.source.connections.failed")
            .tags("pool", dataSourceName)
            .register(registry);

    Gauge.builder("data.source.connections.active", this, metrics -> activeConnections.doubleValue())
            .tags("pool", dataSourceName)
            .register(registry);

    Gauge.builder("data.source.connections.pending", this, metrics -> pendingConnections.doubleValue())
            .tags("pool", dataSourceName)
            .register(registry);

    if (poolMetadata != null) {
        Gauge.builder("data.source.connections.max", this, metrics -> poolMetadata.getMax())
                .tags("pool", dataSourceName)
                .register(registry);

        Gauge.builder("data.source.connections.min", this, metrics -> poolMetadata.getMin())
                .tags("pool", dataSourceName)
                .register(registry);
    }
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
public DataSourceMetricsHolder getMetrics(String dataSourceName) {
    return dataSourceMetrics.computeIfAbsent(dataSourceName, beanName -> {
        DataSource dataSource = applicationContext.getBean(beanName, DataSource.class);
        DataSourcePoolMetadataProviders providers = new DataSourcePoolMetadataProviders(metadataProviders);
        DataSourcePoolMetadata dataSourcePoolMetadata = providers.getDataSourcePoolMetadata(dataSource);
        DataSourceMetricsHolder dataSourceMetricsHolder = new DataSourceMetricsHolder(beanName, dataSourcePoolMetadata, registry);
        return dataSourceMetricsHolder;
    });
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
@Test
public void testReturnDataSourcePoolMetadataProviderForHikari() {
    EnvironmentTestUtils.addEnvironment(context,
            "spring.datasource.type:" + HikariDataSource.class.getName());
    context.register(DataSourceAutoConfiguration.class,
            DataSourceDecoratorAutoConfiguration.class,
            PropertyPlaceholderAutoConfiguration.class);
    context.refresh();

    DataSource dataSource = context.getBean(DataSource.class);
    Assertions.assertThat(dataSource).isInstanceOf(DecoratedDataSource.class);
    DataSourcePoolMetadataProviders poolMetadataProvider = new DataSourcePoolMetadataProviders(context.getBeansOfType(DataSourcePoolMetadataProvider.class).values());
    DataSourcePoolMetadata dataSourcePoolMetadata = poolMetadataProvider.getDataSourcePoolMetadata(dataSource);
    Assertions.assertThat(dataSourcePoolMetadata).isInstanceOf(HikariDataSourcePoolMetadata.class);
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
@Test
public void testReturnDataSourcePoolMetadataProviderForTomcat() {
    context.register(DataSourceAutoConfiguration.class,
            DataSourceDecoratorAutoConfiguration.class,
            PropertyPlaceholderAutoConfiguration.class);
    context.refresh();

    DataSource dataSource = context.getBean(DataSource.class);
    Assertions.assertThat(dataSource).isInstanceOf(DecoratedDataSource.class);
    DataSourcePoolMetadataProviders poolMetadataProvider = new DataSourcePoolMetadataProviders(context.getBeansOfType(DataSourcePoolMetadataProvider.class).values());
    DataSourcePoolMetadata dataSourcePoolMetadata = poolMetadataProvider.getDataSourcePoolMetadata(dataSource);
    Assertions.assertThat(dataSourcePoolMetadata).isInstanceOf(TomcatDataSourcePoolMetadata.class);
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
@Test
public void testReturnDataSourcePoolMetadataProviderForDbcp2() {
    EnvironmentTestUtils.addEnvironment(context,
            "spring.datasource.type:" + org.apache.commons.dbcp2.BasicDataSource.class.getName());
    context.register(DataSourceAutoConfiguration.class,
            DataSourceDecoratorAutoConfiguration.class,
            PropertyPlaceholderAutoConfiguration.class);
    context.refresh();

    DataSource dataSource = context.getBean(DataSource.class);
    Assertions.assertThat(dataSource).isInstanceOf(DecoratedDataSource.class);
    DataSourcePoolMetadataProviders poolMetadataProvider = new DataSourcePoolMetadataProviders(context.getBeansOfType(DataSourcePoolMetadataProvider.class).values());
    DataSourcePoolMetadata dataSourcePoolMetadata = poolMetadataProvider.getDataSourcePoolMetadata(dataSource);
    Assertions.assertThat(dataSourcePoolMetadata).isInstanceOf(CommonsDbcp2DataSourcePoolMetadata.class);
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
private DataSourcePoolMetadata getDataSourcePoolMetadata(DataSource dataSource) {
    return dataSource instanceof DruidDataSource ?
            new DruidDataSourcePoolMetadata((DruidDataSource) dataSource) : null;
}
 

import org.springframework.boot.autoconfigure.jdbc.metadata.DataSourcePoolMetadata; //导入依赖的package包/类
private String getValidationQuery(DataSource source) {
	DataSourcePoolMetadata poolMetadata = this.poolMetadataProvider
			.getDataSourcePoolMetadata(source);
	return (poolMetadata == null ? null : poolMetadata.getValidationQuery());
}