1.导入jdbc场景
<dependency> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-jdbc</artifactId> </dependency>
jdbc中spring boot帮我们导入了，数据库连接池HikariCP、事务spring、jdbc
<dependency> <groupId>com.zaxxer</groupId> <artifactId>HikariCP</artifactId> #数据源，数据库连接池 <version>4.0.3</version> <scope>compile</scope> </dependency> <dependency> <groupId>org.springframework</groupId> <artifactId>spring-jdbc</artifactId> <version>5.3.8</version> <scope>compile</scope> </dependency>
2.导入数据库驱动，以Mysql为例
官方会对MySQL的版本进行仲裁，官方的版本是8.0.25 要与本机数据库版本一致
spring-boot-starter-parent -> spring-boot-dependencies
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-starter-parent</artifactId> <version>2.5.2</version> <relativePath/> <!-- lookup parent from repository --> </parent>
<parent> <groupId>org.springframework.boot</groupId> <artifactId>spring-boot-dependencies</artifactId> <version>2.5.2</version> </parent>
<mysql.version>8.0.25</mysql.version>
3.修改Mysql数据库版本
Ⅰ.固定版本 ，引入固定版本，根据本机版本进行固定更改
<dependency> <groupId>mysql</groupId> <artifactId>mysql-connector-java</artifactId> <version>5.1.38</version> </dependency>
Ⅱ.在properties里面更改mysql的版本,properties里面进行确定各种版本信，因此在pom.xml中也这样进行自定义更改
<properties> <java.version>1.8</java.version> <mysql.version>5.1.38</mysql.version> </properties>
4.分析自动配置
自动配置的类
DataSourceAutoConfiguration //这是数据源的自动配置
@ConditionalOnMissingBean(type = "io.r2dbc.spi.ConnectionFactory") //非响应式数据源时函数下面函数才生效
public class DataSourceAutoConfiguration { @Configuration(proxyBeanMethods = false) @Conditional(EmbeddedDatabaseCondition.class) @ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) @Import(EmbeddedDataSourceConfiguration.class) protected static class EmbeddedDatabaseConfiguration { } @Configuration(proxyBeanMethods = false) @Conditional(PooledDataSourceCondition.class) @ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) @Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class, DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class, DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class }) protected static class PooledDataSourceConfiguration { } /** * {@link AnyNestedCondition} that checks that either {@code spring.datasource.type} * is set or {@link PooledDataSourceAvailableCondition} applies. */ static class PooledDataSourceCondition extends AnyNestedCondition { PooledDataSourceCondition() { super(ConfigurationPhase.PARSE_CONFIGURATION); } @ConditionalOnProperty(prefix = "spring.datasource", name = "type") static class ExplicitType { } @Conditional(PooledDataSourceAvailableCondition.class) static class PooledDataSourceAvailable { } } /** * {@link Condition} to test if a supported connection pool is available. */ static class PooledDataSourceAvailableCondition extends SpringBootCondition { @Override public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) { ConditionMessage.Builder message = ConditionMessage.forCondition("PooledDataSource"); if (DataSourceBuilder.findType(context.getClassLoader()) != null) { return ConditionOutcome.match(message.foundExactly("supported DataSource")); } return ConditionOutcome.noMatch(message.didNotFind("supported DataSource").atAll()); } } /** * {@link Condition} to detect when an embedded {@link DataSource} type can be used. * If a pooled {@link DataSource} is available, it will always be preferred to an * {@code EmbeddedDatabase}. */ static class EmbeddedDatabaseCondition extends SpringBootCondition { private static final String DATASOURCE_URL_PROPERTY = "spring.datasource.url"; private final SpringBootCondition pooledCondition = new PooledDataSourceCondition(); @Override public ConditionOutcome getMatchOutcome(ConditionContext context, AnnotatedTypeMetadata metadata) { ConditionMessage.Builder message = ConditionMessage.forCondition("EmbeddedDataSource"); if (hasDataSourceUrlProperty(context)) { return ConditionOutcome.noMatch(message.because(DATASOURCE_URL_PROPERTY + " is set")); } if (anyMatches(context, metadata, this.pooledCondition)) { return ConditionOutcome.noMatch(message.foundExactly("supported pooled data source")); } EmbeddedDatabaseType type = EmbeddedDatabaseConnection.get(context.getClassLoader()).getType(); if (type == null) { return ConditionOutcome.noMatch(message.didNotFind("embedded database").atAll()); } return ConditionOutcome.match(message.found("embedded database").items(type)); } private boolean hasDataSourceUrlProperty(ConditionContext context) { Environment environment = context.getEnvironment(); if (environment.containsProperty(DATASOURCE_URL_PROPERTY)) { try { return StringUtils.hasText(environment.getProperty(DATASOURCE_URL_PROPERTY)); } catch (IllegalArgumentException ex) { // Ignore unresolvable placeholder errors } } return false; } } }
@ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) //当容器中没有配置数据源时执行下面配置 ,数据库连接池，没有才自动帮忙配置,导入了一堆组件用于配置数据库连接池
@Configuration(proxyBeanMethods = false) @Conditional(PooledDataSourceCondition.class) @ConditionalOnMissingBean({ DataSource.class, XADataSource.class }) @Import({ DataSourceConfiguration.Hikari.class, DataSourceConfiguration.Tomcat.class, DataSourceConfiguration.Dbcp2.class, DataSourceConfiguration.OracleUcp.class, DataSourceConfiguration.Generic.class, DataSourceJmxConfiguration.class }) protected static class PooledDataSourceConfiguration { }
底层配置好的数据库连接池是 HikariDataSource
DataSourceProperties //跟数据库有关的所有配置都在spring.datasource里面绑定
DataSourceTransactionManagerAutoConfiguration //事务管理器的自动配置
JdbcTemplateAutoConfiguration //JdbcTemplate的自动配置,可以对数据库进行CRUD
JdbcProperties //跟jdbc有关的操作都在jdbcproperties里面进行了设置
@ConfigurationProperties(prefix = "spring.jdbc") //可以通过修改这个配置项，来修改jdbctemplate
JndiDataSourceAutoConfiguration // jndi的自动配置
5.编写数据库相关信息的内容，写在配置文件中即可,修改配置项
spring:
datasource:
url: jdbc:mysql://localhost:3306/yschoolmall
username: root
password: 123456
driver-class-name: com.mysql.jdbc.Driver
6.在配置文件中编写查询超时时间，以秒作为单位
jdbc:
template:
query-timeout: 5
7.测试，因为容器中以及有了操作数据库的组件 @Bean @Primary