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SpringBoot2.0.3打印默認數據源為 HikariDataSource (null)

剛剛開始以為DataSource是空對象，后來打印了下面的語句，才知道DataSource不是空的，我砸，我就好奇為什么打印出HikariDataSource (null) 這樣的語句，真的坑。

				?

									@Autowired

									DataSource dataSource;

									@Autowired

									DataSourceProperties dataSourceProperties;

									@Test

									public void contextLoads() throws SQLException {

									    System.out.println(String.format("數據源配置類：用戶名：%s,"

									    +"密碼：%s,資源定位符：%s,驅動：%s"

									            ,dataSourceProperties.getUsername(),

									            dataSourceProperties.getPassword(),

									            dataSourceProperties.getUrl(),

									            dataSourceProperties.getDriverClassName()));

									    System.out.println(dataSource == null);//結果為：false

									    System.out.println("得到的數據源："+dataSource);

									    System.out.println("得到的連接："+dataSource.getConnection());

									}

打印結果

得到的數據源：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.

得到的連接：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默認配置的默認值如下

name	構造器默認值	默認配置validate之后的值	validate重置
minIdle	-1	10	minIdle<0或者minIdle>maxPoolSize,則被重置為maxPoolSize
maxPoolSize	-1	10	如果maxPoolSize小于1，則會被重置。當minIdle<=0被重置為DEFAULT_POOL_SIZE則為10;如果minIdle>0則重置為minIdle的值
maxLifetime	MINUTES.toMillis(30) = 1800000	1800000	如果不等于0且小于30秒則會被重置回30分鐘
connectionTimeout	SECONDS.toMillis(30) = 30000	30000	如果小于250毫秒，則被重置回30秒
validationTimeout	SECONDS.toMillis(5) = 5000	5000	如果小于250毫秒，則會被重置回5秒
loginTimeout	10	30	Math.max(1, (int) MILLISECONDS.toSeconds(500L + connectionTimeout))，為connectionTimeout+500ms轉為秒數取整與 1 取最大者
idleTimeout	MINUTES.toMillis(10) = 600000	600000	如果idleTimeout+1秒>maxLifetime 且 maxLifetime>0，則會被重置為0；如果idleTimeout!=0且小于10秒，則會被重置為10秒
leakDetectionThreshold	0	0	如果大于0且不是單元測試，則進一步判斷：(leakDetectionThreshold < SECONDS.toMillis(2) or (leakDetectionThreshold > maxLifetime && maxLifetime > 0)，會被重置為0 . 即如果要生效則必須>0，而且不能小于2秒，而且當maxLifetime > 0時不能大于maxLifetime
initializationFailTimeout	1	1	-
isAutoCommit	true	true	-
isReadOnly	false	fasle	-
isAllowPoolSuspension	false	false	-
isIsolateInternalQueries	false	false	-
isRegisterMbeans	false	false	-
sealed	false	true	運行啟動后這個標志為true，表示不再運行修改
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屬性：用來驗證數據庫連接的語句，這個語句至少是返回一條數據的查詢語句。每種數據庫都有自己的驗證語句。以下是不同數據庫對應的驗證語句：

validation-query配置數據庫時，屬性validationQuery默認值為“select 1”，對于oracle值應為“select 1 from dual”

validationQuery屬性：用來驗證數據庫連接的語句，這個語句至少是返回一條數據的查詢語句。每種數據庫都有自己的驗證語句。

以下是不同數據庫對應的驗證語句：

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