SpringBootJDBC：加载DataSource过程的源码分析及yml中
DataSo。。。
Spring Boot实现了⾃动加载DataSource及相关配置。当然，使⽤时加上@EnableAutoConfiguration注解是必须的。下⾯就是对这⼀部分的源码分析。
人脉关系（1）Spring Boot启动后会调⽤org.springframework.boot.autoconfigure.jdbc.DataSourceAutoConfiguration。下⾯是部分源码。
1 @Configuration
2 @ConditionalOnClass({ DataSource.class, EmbeddedDatabaType.class })
3 @EnableConfigurationProperties(DataSourceProperties.class)
4 @Import({ DataSourcePoolMetadataProvidersConfiguration.class,
5 DataSourceInitializationConfiguration.class })
6 public class DataSourceAutoConfiguration {
7
8 @Configuration
9 @Conditional(EmbeddedDatabaCondition.class)
10 @ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
11 @Import(EmbeddedDataSourceConfiguration.class)
hottie12 protected static class EmbeddedDatabaConfiguration {
13 }
14
15 @Configuration
16 @Conditional(PooledDataSourceCondition.class)
17 @ConditionalOnMissingBean({ DataSource.class, XADataSource.class })
18 @Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class,
19 DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.Generic.class,
20 DataSourceJmxConfiguration.class })
21 protected static class PooledDataSourceConfiguration {
22 }
23 ......
24 }
我们从中可以看出，DataSourceAutoConfiguration中有两个嵌套类，⼀个是EmbeddedDatabaConfiguration，另⼀个是PooledDataSourceConfiguration。北京培训学校
resistEmbeddedDatabaConfiguration表⽰已经嵌⼊Spring Boot的DataSource，除了Maven中加⼊相应的Driver，可以不做其他额外配置就能使⽤。从EmbeddedDatabaType类可以看出，Spring Boot的内嵌DataSource⽀持HSQL，H2，DERBY这三种DB。PooledDataSourceConfiguration表⽰Spring B
oot还⽀持⼀些实现Pool的DataSource。从org.springframework.boot.jdbc.DataSourceBuilder 中可以看出，当前版本的Spring Boot（2.0）只⽀持
com.zaxxer.hikari.HikariDataSource，at.jdbc.pool.DataSource，s.dbcp2.BasicDataSource。其中，性能更加优秀的HikariDataSource是Spring Boot的默认选择（DataSourceBuilder中DATA_SOURCE_TYPE_NAMES[0] =
com.zaxxer.hikari.HikariDataSource）。所以，当l⽂件中做如下配置时，Spring Boot默认使⽤HikariDataSource数据库连接池。
spring:
triodatasource:
url: jdbc:mysql://localhost:3306/sas
urname: root
password: ****
driver-class-name: sql.jdbc.Driver
#type: com.zaxxer.hikari.HikariDataSource
（2）我们以HikariDataSource举例，接下来调⽤PooledDataSourceConfiguration中
actualorg.springframework.boot.autoconfigure.jdbc.DataSourceConfiguration抽象类的Hikari嵌套类（DataSourceConfiguration抽象类的⼀个实现类）。
1 abstract class DataSourceConfiguration {
2
3 @SuppressWarnings("unchecked")
4 protected <T> T createDataSource(DataSourceProperties properties,
5 Class<? extends DataSource> type) {
6 return (T) properties.initializeDataSourceBuilder().type(type).build();
7 }
8英语26个字母正确发音视频教程
9 /* Omit Tomcat Pool DataSource configuration.*/
10 /**
11 * Hikari DataSource configuration.
12 */
13 @ConditionalOnClass(HikariDataSource.class)
14 @ConditionalOnProperty(name = "pe", havingValue = "com.zaxxer.hikari.HikariDataSource", matchIfMissing = true)
15 static class Hikari extends DataSourceConfiguration {
16
17 @Bean
18 @ConfigurationProperties(prefix = "spring.datasource.hikari")
19 public HikariDataSource dataSource(DataSourceProperties properties) {
20 HikariDataSource dataSource = createDataSource(properties,
21 HikariDataSource.class);
22 if (StringUtils.Name())) {
23 dataSource.Name());
24 }
25 return dataSource;
26 }
27 }
28 /* Omit DBCP DataSource configuration.*/
29 }
我们从黄⾊部分可以看出，当l⽂件中配置pe = com.zaxxer.hikari.
HikariDataSource时，会使⽤HikariDataSource作为数据库连接池（当然上⾯也分析了，它是默认选择）。我们从绿⾊部分可以看出它的配置信息主要从两个类中读取，⼀个是org.springframework.boot.autoconfigure.jdbc.DataSourceProperties，另⼀个则是本类HikariDataSource的⽗类
com.zaxxer.hikari.HikariConfig。constant
@ConfigurationProperties(prefix = "spring.datasource")
public class DataSourceProperties implements BeanClassLoaderAware, InitializingBean {}
韩文转换器@ConfigurationProperties(prefix = "spring.datasource.hikari")
public HikariDataSource dataSource(DataSourceProperties properties) {}
我们从@ConfigurationProperties配置及两个具体的类所包含的的域可以得出配置HikariDataSource信息。下⾯是例⼦。
spring:
datasource:
name: #Name of the datasource. Default to "testdb" when using an embedded databa.
driverClassName: #Fully qualified name of the JDBC driver. Auto-detected bad on the URL by default.
url: #DBC URL of the databa.
type: #Fully qualified name of the connection pool implementation to u. By default, it is auto-detected from the classpath.
urname: #Login urname of the databa.
password: #Login password of the databa.
## For more details plea e DataSourceProperties.
hikari:
connectionTimeout:
validationTimeout:
maxPoolSize:
minIdle:
dataSourceProperties:
## For more details plea e HikariConfig.
（3）当读完配置后，则会通过Connection()⽅法创建HikariPool对象。HikariPool及其⽗类PoolBa做了许多复杂的⼯作，包括创建Pool，创建Connection，读取Config，验证等等。调⽤Connection()⽅法最终得到了这个Connection 对象。这个过程中主要做了以下⼏步：
①创建HikariPool对象。
②调⽤HikariPool对象的⽗类对象PoolBa的构造器，读取HikariConfig配置信息配置PoolBa的属性。
③调⽤PoolBa的构造器的initializeDataSource⽅法，利⽤com.zaxxer.hikari.util.DriverDataSource创建DataSource对象（这⾥主要指JDBC URL⽅式）。DriverDataSource中会把所有的DataSource信
息封装到driverProperties属性中，这是为了适配java.sql.Driver的connect(String url, java.util.Properties info)⽅法。
1 public final class DriverDataSource implements DataSource {
2
3 private final String jdbcUrl;
4 private final Properties driverProperties;
5 private Driver driver;
6
7 public DriverDataSource(String jdbcUrl, String driverClassName, Properties properties, String urname, String password) {
8 this.jdbcUrl = jdbcUrl;
9 this.driverProperties = new Properties();
10 Iterator e = Set().iterator();
11
12 while(e.hasNext()) {
13 Entry driverClass = (();
14 this.driverProperties.Key().toString(), Value().toString());
15 }
16
17 if(urname != null) {
18 this.driverProperties.put("ur", Property("ur", urname));
19 }
20
21 if(password != null) {
22 this.driverProperties.put("password", Property("password", password));
23 }
美眉制造机
24 ......
25 }
26
27 @Override
28 public Connection getConnection() throws SQLException
29 {
30 t(jdbcUrl, driverProperties);
31 }
32 }
④调⽤HikariPool对象的构造器，同样也是配置⼀堆线程池信息。
⑤返回Connection()。这个过程中，做了包含wPoolEntry()及wConnection()的许多复杂⽅法。从wConnection()可以看出，最终还是调⽤的步骤③的getConnection()⽅法获取到了这个Connection对象。
1 private Connection newConnection() throws Exception
2 {
3 final long start = currentTime();
4
5 Connection connection = null;
6 try {
7 String urname = Urname();
8 String password = Password();
9
10 connection = (urname == null) ? Connection() : Connection(urname, password);
11 if (connection == null) {
12 throw new SQLTransientConnectionException("DataSource returned null unexpectedly");
13 }
14
15 tupConnection(connection);
16 lastConnectionFailure.t(null);
17 return connection;
18 }
19 catch (Exception e) {
20 if (connection != null) {
21 quietlyCloConnection(connection, "(Failed to create/tup connection)");
22 }
23 el if (getLastConnectionFailure() == null) {
24 LOGGER.debug("{} - Failed to create/tup connection: {}", poolName, e.getMessage());
25 }
26
27 lastConnectionFailure.t(e);
28 throw e;
29 }
30 finally {
31 // tracker will be null during failFast check
32 if (metricsTracker != null) {
33 dConnectionCreated(elapdMillis(start));
34 }
35 }
36 }
