SpringBoot2.0.3打印默认数据源为 HikariDataSource (null)问题_Java教程

SpringBoot2.0.3打印默认数据源为 HikariDataSource (null)

刚刚开始以为DataSource是空对象，后来打印了下面的语句，才知道DataSource不是空的，我砸，我就好奇为什么打印出HikariDataSource (null) 这样的语句，真的坑。

				?

									@Autowired

									DataSource dataSource;

									@Autowired

									DataSourceProperties dataSourceProperties;

									@Test

									public void contextLoads() throws SQLException {

									    System.out.println(String.format("数据源配置类：用户名：%s,"

									    +"密码：%s,资源定位符：%s,驱动：%s"

									            ,dataSourceProperties.getUsername(),

									            dataSourceProperties.getPassword(),

									            dataSourceProperties.getUrl(),

									            dataSourceProperties.getDriverClassName()));

									    System.out.println(dataSource == null);//结果为：false

									    System.out.println("得到的数据源："+dataSource);

									    System.out.println("得到的连接："+dataSource.getConnection());

									}

打印结果

得到的数据源：HikariDataSource (null) 2020-09-08 00:16:53.612 INFO 13316 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Starting... Tue Sep 08 00:16:53 CST 2020 WARN: Establishing SSL connection without server's identity verification is not recommended. According to MySQL 5.5.45+, 5.6.26+ and 5.7.6+ requirements SSL connection must be established by default if explicit option isn't set. For compliance with existing applications not using SSL the verifyServerCertificate property is set to 'false'. You need either to explicitly disable SSL by setting useSSL=false, or set useSSL=true and provide truststore for server certificate verification. 2020-09-08 00:16:54.330 INFO 13316 --- [ main] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Start completed.

得到的连接：HikariProxyConnection@722513129 wrapping com.mysql.jdbc.JDBC4Connection@52169758 2020-09-08 00:16:54.335 INFO 13316 --- [ Thread-2] o.s.w.c.s.GenericWebApplicationContext : Closing org.springframework.web.context.support.GenericWebApplicationContext@5b799640: startup date [Tue Sep 08 00:16:51 CST 2020]; root of context hierarchy 2020-09-08 00:16:54.337 INFO 13316 --- [ Thread-2] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown initiated... 2020-09-08 00:16:54.339 INFO 13316 --- [ Thread-2] com.zaxxer.hikari.HikariDataSource : HikariPool-1 - Shutdown completed.

需要注意

SpringBoot2.0.3使用的Driver是com.mysql.jdbc.Driver

springboot的HikariDataSource默认配置的默认值如下

name	构造器默认值	默认配置validate之后的值	validate重置
minIdle	-1	10	minIdle<0或者minIdle>maxPoolSize,则被重置为maxPoolSize
maxPoolSize	-1	10	如果maxPoolSize小于1，则会被重置。当minIdle<=0被重置为DEFAULT_POOL_SIZE则为10;如果minIdle>0则重置为minIdle的值
maxLifetime	MINUTES.toMillis(30) = 1800000	1800000	如果不等于0且小于30秒则会被重置回30分钟
connectionTimeout	SECONDS.toMillis(30) = 30000	30000	如果小于250毫秒，则被重置回30秒
validationTimeout	SECONDS.toMillis(5) = 5000	5000	如果小于250毫秒，则会被重置回5秒
loginTimeout	10	30	Math.max(1, (int) MILLISECONDS.toSeconds(500L + connectionTimeout))，为connectionTimeout+500ms转为秒数取整与 1 取最大者
idleTimeout	MINUTES.toMillis(10) = 600000	600000	如果idleTimeout+1秒>maxLifetime 且 maxLifetime>0，则会被重置为0；如果idleTimeout!=0且小于10秒，则会被重置为10秒
leakDetectionThreshold	0	0	如果大于0且不是单元测试，则进一步判断：(leakDetectionThreshold < SECONDS.toMillis(2) or (leakDetectionThreshold > maxLifetime && maxLifetime > 0)，会被重置为0 . 即如果要生效则必须>0，而且不能小于2秒，而且当maxLifetime > 0时不能大于maxLifetime
initializationFailTimeout	1	1	-
isAutoCommit	true	true	-
isReadOnly	false	fasle	-
isAllowPoolSuspension	false	false	-
isIsolateInternalQueries	false	false	-
isRegisterMbeans	false	false	-
sealed	false	true	运行启动后这个标志为true，表示不再运行修改
poolName	null	HikariPool-1	-
catalog	null	null	-
connectionInitSql	null	null	-
connectionTestQuery	null	null	-
dataSourceClassName	null	null	-
schema	null	null	-
transactionIsolationName	null	null	-
dataSource	null	null	-
dataSourceProperties	{}	{}	-
threadFactory	null	null	-
scheduledExecutor	null	null	-
metricsTrackerFactory	null	null	-
metricRegistry	null	null	-
healthCheckRegistry	null	null	-
healthCheckProperties	{}	{}	-
validation-query			validationQuery属性：用来验证数据库连接的语句，这个语句至少是返回一条数据的查询语句。每种数据库都有自己的验证语句。以下是不同数据库对应的验证语句：

validation-query配置数据库时，属性validationQuery默认值为“select 1”，对于oracle值应为“select 1 from dual”

validationQuery属性：用来验证数据库连接的语句，这个语句至少是返回一条数据的查询语句。每种数据库都有自己的验证语句。

以下是不同数据库对应的验证语句：

DataBase	validationQuery
hsqldb	select 1 from INFORMATION_SCHEMA.SYSTEM_USERS
Oracle	select 1 from dual
DB2	select 1 from sysibm.sysdummy1
MySql	select 1
Microsoft SqlServer	select1
postgresql	select version()
ingres	select 1
derby	values 1
H2	select 1