title: Spring @Value Could not resolve placeholder in string value
body: <p>Have the context spring conf like this, I have 2 property-placeholder in my context.</p>
  
  <pre><code>&lt;?xml version="1.0" encoding="UTF-8"?&gt;
  &lt;beans&gt;
      &lt;context:annotation-config/&gt;
      &lt;context:component-scan base-package="com.xxx.app.xxx"/&gt;
  
      &lt;context:property-placeholder location="classpath:em-management.properties"/&gt;
      &lt;context:property-placeholder location="file:///opt/ass/swp/conf/platform.properties"/&gt;
  
  &lt;/beans&gt;
  </code></pre>
  
  <p>When I run the code, met this error:</p>
  
  <pre><code> org.springframework.beans.factory.BeanCreationException: Error creating bean with name 'CMClient': Injection of autowired dependencies failed; nested exception is org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String com.xxxx.app.xxxx.xx.client.CMClient.washost; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'com.ibm.CORBA.securityServerHost' in string value "${com.ibm.CORBA.securityServerHost}"
  
  Caused by: org.springframework.beans.factory.BeanCreationException: Could not autowire field: private java.lang.String com.xxxx.app.xxx.xxx.client.CMClient.washost; nested exception is java.lang.IllegalArgumentException: Could not resolve placeholder 'com.ibm.CORBA.securityServerHost' in string value "${com.ibm.CORBA.securityServerHost}"
  
  Caused by: java.lang.IllegalArgumentException: Could not resolve placeholder 'com.ibm.CORBA.securityServerHost' in string value "${com.ibm.CORBA.securityServerHost}"
  </code></pre>
  
  <p>how to solve this issue？</p>