import使用占位符
连接池切换导入配置的代码：
<import resource="classpath:META-INF/spring/spring-${db.connection.pool}.xml" />
在配置文件添加配置
db.connection.pool=druid
启动直接报错，读取不到配置，因为属性文件的加载在import配置文件之后。
Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'db.connection.pool' in value "classpath:META-INF/spring/spring-${db.connection.pool}.xml"
所以，要在应用启动的时候添加属性
1、添加AppContextInitializer启动类：
public class AppContextInitializer implements ApplicationContextInitializer<ConfigurableApplicationContext> { private Logger logger = Logger.getLogger(AppContextInitializer.class); @Override public void initialize(ConfigurableApplicationContext applicationContext) { ResourcePropertySource propertySource = null; try { propertySource = new ResourcePropertySource("classpath:config/db-config.properties"); } catch (IOException e) { logger.error("加载配置文件[config/db-config.properties]失败"); } applicationContext.getEnvironment().getPropertySources().addFirst(propertySource); } }
2、在web.xml中添加配置：
context-param> <param-name>contextInitializerClasses</param-name> <param-value>com.example.AppContextInitializer</param-value> </context-param>
启动配置文件加载正常。
