spring jdbc数据源

0. 所有jdbc的先决条件

配置数据源，spring里面是配置一个datasource bean。

1. maven依赖

需要导入jdbc包，spring包,h2包

<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-jdbc</artifactId>
		<version>4.0.5.RELEASE</version>
	</dependency>

	<dependency>
		<groupId>org.springframework</groupId>
		<artifactId>spring-context</artifactId>
		<version>4.0.5.RELEASE</version>
	</dependency>

   	<dependency>
		<groupId>com.h2database</groupId>
		<artifactId>h2</artifactId>
		<version>1.3.175</version>
	</dependency>

2. 运行h2数据库

可以网上找h2的二进制包运行，也可以直接在idea里面找到org.h2.tools.Console类运行。
用户名sa,密码为空。

3. 创建一个spring bean配置类，使用DriverManagerDataSource定义一个datasource bean

@Configuration
public class Ch4Configuration {
    @Bean
    public DataSource dataSource() {
        DriverManagerDataSource dataSource = new DriverManagerDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl("jdbc:h2:tcp://localhost/~/test");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }
}

DriverManagerDataSource还有一个子类SingleConnectionDataSource，该类重复使用相同的连接。

public class Ch4Configuration {
    @Bean
    public DataSource dataSource() {
        SingleConnectionDataSource dataSource = new SingleConnectionDataSource();
        dataSource.setSuppressClose(true);
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl("jdbc:h2:tcp://localhost/~/test");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }
}

4. 生产环境下使用连接池化的datasource

比如C3P0,或者DBCP，

		<dependency>
			<groupId>commons-dbcp</groupId>
			<artifactId>commons-dbcp</artifactId>
			<version>1.4</version>
		</dependency>

import org.apache.commons.dbcp.BasicDataSource;
@Configuration
public class Ch4ConfigurationForPooledDS1 {
    
    @Bean(destroyMethod="close")
    public DataSource dataSource() {
        BasicDataSource dataSource = new BasicDataSource();
        dataSource.setDriverClassName("org.h2.Driver");
        dataSource.setUrl("jdbc:h2:tcp://localhost/~/test");
        dataSource.setUsername("sa");
        dataSource.setPassword("");
        return dataSource;
    }
}

		<dependency>
			<groupId>com.mchange</groupId>
			<artifactId>c3p0</artifactId>
			<version>0.9.2.1</version>
		</dependency>


import com.mchange.v2.c3p0.ComboPooledDataSource;
@Configuration
public class Ch4ConfigurationForPooledDS2 {
    
    @Bean(destroyMethod="close")
    public DataSource dataSource() throws Exception {
        ComboPooledDataSource dataSource = new ComboPooledDataSource();
        dataSource.setDriverClass("org.h2.Driver");
        dataSource.setJdbcUrl("jdbc:h2:tcp://localhost/~/test");
        dataSource.setUser("sa");
        dataSource.setPassword("");
        return dataSource;
    }
}

5. 获取connection

public class Main {
	public static void main(String[] args) throws SQLException {
		AnnotationConfigApplicationContext applicationContext = new AnnotationConfigApplicationContext(Ch4Configuration.class);
		DataSource dataSource = applicationContext.getBean("dataSource", DataSource.class);
		
		Connection connection = dataSource.getConnection();
		System.out.println(connection.isClosed());
		connection.close();
		System.out.println(connection.isClosed());
	}
}

所有datasource 都实现了getConnection()接口，直接调用即可。这样我们就通过jdbc 数据源，获取了数据库连接。