Spring读取properties资源文件

　　我们知道可以通过读取资源文件流后加载到Properties对象，再使用该对象方法来获取资源文件。现在介绍下利用Spring内置对象来读取资源文件。

　　系统启动时加载资源文件链路：web.xml -->  spring-core.xml --> sysconfig.properties

　　接下来直接看代码吧

web.xml

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>classpath:spring-core.xml</param-value>
    </context-param>

spring-core.xml

    <!-- 加载properties里的内容 -->
    <bean id="PropertyConfig" class="com.wulinfeng.PropertiesConfig">
        <property name="ignoreUnresolvablePlaceholders" value="true" />
        <property name="locations">
            <list>               
                <value>classpath:sysconfig.properties</value>
            </list>
        </property>
        <property name="fileEncoding">
            <value>UTF-8</value>
        </property>
    </bean>

PropertiesConfig.java

public class PropertiesConfig extends PropertyPlaceholderConfigurer
{
    private static Map<String, String> propertyMap;
    
    @Override
    protected void processProperties(ConfigurableListableBeanFactory beanFactoryToProcess, Properties props)
        throws BeansException
    {
        super.processProperties(beanFactoryToProcess, props);
        if (propertyMap == null || propertyMap.size() == 0)
        {
            propertyMap = new HashMap<String, String>();
            
            for (Object key : props.keySet())
            {
                String keyStr = key.toString();
                String value = props.getProperty(keyStr);
                propertyMap.put(keyStr, value);
            }
        }
    }
    
    public static String getProperty(String name,String def)
    {
        if (propertyMap == null || propertyMap.isEmpty() || null == propertyMap.get(name))
        {
            return def;
        }
        return propertyMap.get(name);
    }
    
    public static String getProperty(String name)
    {
        if (propertyMap == null || propertyMap.isEmpty())
        {
            return null;
        }
        return propertyMap.get(name);
    }
    
}

　　注意这里需要继承Spring的PropertyPlaceholderConfigurer类。