Run Into Problem When Move Hard Coding to a properties File

[JiaPei Jen]

My code (using the JavaMail API) works fine when the SMTP host name is hard coded in the program:

       Properties props = System.getProperties();
       props.put( "mail.smtp.host", "TheHostName" );

Then, I tried to put the host name in a properties file (smtpServer.properties). The properties file is in the $TOMCATHOME\webapps\AppName\WEB-INF\classes\resources directory. And the properties file has this one single line:

smtpServer = TheHostName     //Note: The host name has only alpha characters, dots, and dashes

In my program, I did:

   private final String PROPFILE = "resources/smtpServer.properties";
   private Properties oProp = null;
 
   public SendBatchMails()  // this is the constructor in my class
   {
      try
      {
         oProp = new Properties();
         oProp.load ( getClass().getClassLoader().getResourceAsStream( PROPFILE ) );
      }
      catch( IOException oEx )
      {
         System.out.println("Unable to load the Properties " + PROPFILE + oEx );
      }
    }
 
    ......
 
       String smtpServer = oProp.getProperty( "smtpServer" );
       Properties props = System.getProperties();
       props.put( "mail.smtp.host", smtpServer );

And, I got this runtime error:

java.lang.IllegalArgumentException: argument type mismatch
sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
java.lang.reflect.Method.invoke(Method.java:324)
org.apache.commons.beanutils.PropertyUtils.setSimpleProperty(PropertyUtils.java:1789)
org.apache.commons.beanutils.PropertyUtils.setNestedProperty(PropertyUtils.java:1684)
org.apache.commons.beanutils.PropertyUtils.setProperty(PropertyUtils.java:1713)
org.apache.commons.beanutils.BeanUtils.setProperty(BeanUtils.java:1019)
org.apache.commons.beanutils.BeanUtils.populate(BeanUtils.java:808)
org.apache.struts.util.RequestUtils.populate(RequestUtils.java:1252)
org.apache.struts.action.RequestProcessor.processPopulate(RequestProcessor.java:821)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:254)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1482)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:525)
javax.servlet.http.HttpServlet.service(HttpServlet.java:709)
javax.servlet.http.HttpServlet.service(HttpServlet.java:802)

[Ron Perich]

A couple of things you might try:

First, I would try to do a sysout on the actual String you think you are getting back from the properties file. Chances are, this will tell you if you're getting a null String or not. Second, you may want to use the File.separator in your file path for the properties file. File.separator will ensure that no matter what type of OS this is running on, you will always get the proper folder separator and don't have to worry about escaping the file separator character.