数据库在Spring中配置

1. applicationContext.xml中，以Bean的形式出现，因为其也是一种资源

<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <proprety name="diverClass" value="com.mysql.jdbc.Driver">
    <proprety name="jdbcUrl" value="jdbc:mysql://localhost:3306/xxx">
    <proprety name="user" value="root">
    <proprety name="password" value="root">
</bean>

2. 将资源与bean的配置分开，eg.datasourse
   资源信息放入jdbc.properties文件，xml或JdbcConfig中通过${...}获取

jdbc.properties

jdbc.diverClass=com.mysql.jdbc.Driver
jdbc.jdbcUrl=jdbc:mysql://localhost:3306/xxx
jdbc.user=root
jdbc.password=root

<bean id="runner" class="org.apache.commons.dbutils.QueryRunner">
    <constructor-arg index="0" ref="dataSource"></constructor-arg>
</bean>
<bean id="dataSource" class="com.mchange.v2.c3p0.ComboPooledDataSource">
    <proprety name="diverClass" value="${jdbc.diverClass}">
    <proprety name="jdbcUrl" value="${jdbc.jdbcUrl}">
    <proprety name="user" value="${jdbc.user}">
    <proprety name="password" value="${jdbc.password}">
</bean>

或

public class JdbcConfig{
    @Value(${jdbc.diverClass})
    private String diverClass;
    
    @Value(${jdbc.jdbcUrl})
    private String jdbcUrl
    
    @Value(${jdbc.user})
    private String user
    
    @Value(${jdbc.password})
    private String password
    
    @Bean(name="runner")
    puclic QueryRunner getQueryRunner(@Qualifier("dataSource") DataSource ds){
        return new QueryRunner(ds)
    }
    
    @Bean(name="dataSource")
    public DataSource getDataSource(){
    ComboPooledDataSource dataSource = new ComboPooledDataSource();
    
    dataSource.setDriverClass(driverClass);
    dataSource.setJdbcUrl(url);
    dataSource.setUser(user);
    dataSource.setPassword(password);
    return dataSource;

    }
}

3. xml需要先加载properties文件

<context:property-placeholder location="jdbc.properties"/>

或在最终引入的配置类中添加

@Bean
public PropertySourcesPlaceholderConfigurer createPropertySourcesPlaceholderConfigurer(){
    return new PropertySourcesPlaceholderConfigurer();
}