public class EncryptPropertyPlaceholderConfigurer extends PropertyPlaceholderConfigurer {
  private String[] encryptPropNames = {"username", "password"}; 

 @Override
 protected void processProperties(ConfigurableListableBeanFactory beanFactory,
   Properties props) throws BeansException {
  try {
  for (int i = 0;i<encryptPropNames.length;i++){
    String value = props.getProperty(encryptPropNames[i]);
       if (value != null) {
     props.setProperty(encryptPropNames[i],new String(DES.decrypt(new BASE64Decoder().decodeBuffer(value), "解密秘钥")));
       }
      
  }
  super.processProperties(beanFactory, props);
  } catch (Exception e) {
    e.printStackTrace();
       throw new BeanInitializationException(e.getMessage());
  }
 } 
}

<!-- class填写刚才那段代码的类路径-->
<bean id="propertyConfigurer" class="com.**.EncryptPropertyPlaceholderConfigurer"> 
      <property name="locations">
        <list>
          <value>classpath:jdbc.properties</value>
        </list>
      </property>
  </bean>