import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
@Override
public void validate(UIValidationContext validator)
{
   final DatabaseType database = dbType.getValue();
   final DatabaseDriver driver = DatabaseDriver.fromProductName(database.name());
   if (driver.equals(DatabaseDriver.UNKNOWN))
   {
      // Spring Boot doesn't know about this DB
      validator.addValidationError(dbType, "Spring Boot doesn't know about DB '" + dbType.getName() + "'");
   }

   if (isNotEmbeddedDB(database) && !databaseURL.hasValue() && !dataSourceName.hasValue())
   {
      validator.addValidationError(dataSourceName, "Either DataSource name or database URL is required");
      validator.addValidationError(databaseURL, "Either DataSource name or database URL is required");
   }
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
private XADataSource createXaDataSource(DataSourceProperties properties)
    throws ClassNotFoundException, LinkageError {
  String className = Optional
      .ofNullable(properties.getXa())
      .map(Xa::getDataSourceClassName)
      .map(String::trim)
      .map(Strings::emptyToNull)
      .orElseGet(() -> DatabaseDriver
          .fromJdbcUrl(properties.determineUrl())
          .getXaDataSourceClassName());
  Assert.state(StringUtils.hasLength(className),
      "No XA DataSource class name specified or inferred");
  XADataSource dataSource = createXaDataSourceInstance(className);
  bindXaProperties(dataSource, properties);
  return dataSource;
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
protected org.apache.tomcat.jdbc.pool.DataSource createTomcatDataSource(DataSourceProperties properties) {
	org.apache.tomcat.jdbc.pool.DataSource dataSource = createDataSource(
			properties, org.apache.tomcat.jdbc.pool.DataSource.class);
	DatabaseDriver databaseDriver = DatabaseDriver
			.fromJdbcUrl(properties.determineUrl());
	String validationQuery = databaseDriver.getValidationQuery();
	if (validationQuery != null) {
		dataSource.setTestOnBorrow(true);
		dataSource.setValidationQuery(validationQuery);
	}
	return dataSource; 
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
protected String getValidationQuery(String product) {
	String query = this.query;
	if (!StringUtils.hasText(query)) {
		DatabaseDriver specific = DatabaseDriver.fromProductName(product);
		query = specific.getValidationQuery();
	}
	if (!StringUtils.hasText(query)) {
		query = DEFAULT_QUERY;
	}
	return query;
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
private XADataSource createXaDataSource() {
	String className = this.properties.getXa().getDataSourceClassName();
	if (!StringUtils.hasLength(className)) {
		className = DatabaseDriver.fromJdbcUrl(this.properties.determineUrl())
				.getXaDataSourceClassName();
	}
	Assert.state(StringUtils.hasLength(className),
			"No XA DataSource class name specified");
	XADataSource dataSource = createXaDataSourceInstance(className);
	bindXaProperties(dataSource, this.properties);
	return dataSource;
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
private void maybeGetDriverClassName() {
	if (!this.properties.containsKey("driverClassName")
			&& this.properties.containsKey("url")) {
		String url = this.properties.get("url");
		String driverClass = DatabaseDriver.fromJdbcUrl(url).getDriverClassName();
		this.properties.put("driverClassName", driverClass);
	}
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
@Test
public void tomcatValidatesConnectionByDefault() {
	org.apache.tomcat.jdbc.pool.DataSource dataSource = autoConfigureDataSource(
			org.apache.tomcat.jdbc.pool.DataSource.class);
	assertThat(dataSource.isTestOnBorrow()).isTrue();
	assertThat(dataSource.getValidationQuery())
			.isEqualTo(DatabaseDriver.HSQLDB.getValidationQuery());
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
@Test
public void commonsDbcpValidatesConnectionByDefault() {
	BasicDataSource dataSource = autoConfigureDataSource(BasicDataSource.class,
			"org.apache.tomcat", "com.zaxxer.hikari");
	assertThat(dataSource.getTestOnBorrow()).isTrue();
	assertThat(dataSource.getValidationQuery())
			.isEqualTo(DatabaseDriver.HSQLDB.getValidationQuery());
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
private String driverClassName() {
    if (StringUtils.hasText(driverClassName)) {
        return driverClassName;
    }
    return DatabaseDriver.fromJdbcUrl(url).getDriverClassName();
}
 

import org.springframework.boot.jdbc.DatabaseDriver; //导入依赖的package包/类
private String validationQuery() {
    if (StringUtils.hasText(validationQuery)) {
        return validationQuery;
    }
    return DatabaseDriver.fromJdbcUrl(url).getValidationQuery();
}