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Spring Boot 学习（一） 数据库访问

bubuko 2022/1/25 19:01:33 java 字数 26682 阅读 802 来源 http://www.bubuko.com/infolist-5-1.html

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 ...

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>

技术分享图片

 

 

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
技术分享图片 
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;
        }

    }

}
View Code 
　　@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
技术分享图片 
@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 {

    }
View Code

　　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
 
 
Spring Boot 学习（一） 数据库访问
原文：https://www.cnblogs.com/YuyuFishSmile/p/14956972.html
 



                        

                            
                           
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