Spring如何加载Properties文件

Spring的框架中，org.springframework.beans.factory.config.PropertyPlaceholderConfigurer类可以将.properties(key/value形式)文件中
一些动态设定的值(value)，在XML中替换为占位该键($key$key)的值，
.properties文件可以根据客户需求，自定义一些相关的参数，这样的设计可提供程序的灵活性。

xml中的配置文件

<!-- 开发环境配置文件 -->
	<bean id="developCustomProperties"
		class="cn.lision.iems.admin.support.properties.ApplicationConfigurer">
		<property name="fileEncoding" value="utf-8" />
		<property name="locations">
			<list>
				<value>classpath:/conf/dev/application.required.properties</value>
				<value>classpath:/conf/dev/application.custom.properties</value>
			</list>
		</property>
	</bean>

public class ApplicationConfigurer extends PropertyPlaceholderConfigurer {

	private static Map<String, Object> ctxPropertiesMap;

	@Override
	protected void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props)
			throws BeansException {
		super.processProperties(beanFactory, props);

		ctxPropertiesMap = new HashMap<String, Object>();
		for (Object key : props.keySet()) {
			String keyStr = key.toString();
			String value = props.getProperty(keyStr);
			ctxPropertiesMap.put(keyStr, value);
		}
	}

	public static Object getProperty(String name) {

		return ctxPropertiesMap.get(name);
	}

	public static Map<String, Object> getProperties() {

		return ctxPropertiesMap;
	}
	
	public static void setProperty(Map<String, Object> map){
		ctxPropertiesMap.putAll(map);
	}

	public static String getStringProperty(String name, String replaceValue) {
		Map<String, Object> variableMap = Cache.get(Constant.VARIABLE_CACHE_KEY);
		if(variableMap==null){
			return replaceValue;
		}
		Object object = variableMap.get(name);
		if (object == null) {
			return replaceValue;
		}
		return String.valueOf(object);

	}
}

以上是例一，以下是例二

<bean id="propertyConfigurer" 
class="com.datasure.util.filter.EncryptablePropertyPlaceholderConfigurer"> 
<property name="locations"> 
<list><value>classpath:jdbc.properties</value></list> 
</property> 
</bean>

public class EncryptablePropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
    private static final String key = "helloworld";

    protected void processProperties(ConfigurableListableBeanFactory beanFactory, Properties props)
        throws BeansException {
            try {
                Des des = new Des();
                String username = props.getProperty("jdbc.username");
                if (username != null) {
                    props.setProperty("jdbc.username", des.Decrypt(username, des.hex2byte(key)));
                }
                
                String password = props.getProperty("jdbc.password");
                if (password != null) {
                    props.setProperty("jdbc.password", des.Decrypt(password, des.hex2byte(key)));
                }
                
                String url = props.getProperty("jdbc.url");
                if (url != null) {
                    props.setProperty("jdbc.url", des.Decrypt(url, des.hex2byte(key)));
                }
                
                String driverClassName = props.getProperty("jdbc.driverClassName");
                if(driverClassName != null){
                    props.setProperty("jdbc.driverClassName", des.Decrypt(driverClassName, des.hex2byte(key)));
                }
                
                super.processProperties(beanFactory, props);
            } catch (Exception e) {
                e.printStackTrace();
                throw new BeanInitializationException(e.getMessage());
            }
        }
    }
    //通过如上配置就可以对配置文件进行解密操作