为什么我无法在类路径中使用getResourceAsStream读取属性文件（在WEB-INF / lib下）

Question

I was testing out reading a properties file using getResourceAsStream when the properties file is in classpath (under WEB-INF\\lib folder). And it is not working for some reason. Can anybody tell me what I am doing wrong?

This is my environment: Operating system is Windows 7. IDE is Eclipse 4.2.3 Kepler 64-bit. Server is Tomcat 6.0.37 running on 8081 port.

I created a web application MyWebProject .

I have a app.properties file which is located in WEB-INF\\lib folder. This is the content of app.properties file:

DataSource=jdbc/MyDB

I created a class AppProperties which reads this file. This is the class:

public final class AppProperties {

    private static String DATA_SOURCE_NAME;

    public static String getDataSourceName() {
        return DATA_SOURCE_NAME;
    }

    static {

        ClassLoader classLoader = null;
        InputStream propertiesFile = null;
        Properties properties = null;
        final String PROPERTIES_FILE_NAME = "app.properties";

        properties = new Properties();
        classLoader = Thread.currentThread().getContextClassLoader();
        System.out.println("AppProperties: Name of classLoader = " + classLoader.getClass().getName());
        propertiesFile = classLoader.getResourceAsStream(PROPERTIES_FILE_NAME);
        System.out.println("AppProperties: propertiesFile = " + propertiesFile);

    }
}

Then I created a Servlet AppPropertiesServlet to test it out:

public class AppPropertiesServlet extends HttpServlet {

    public AppPropertiesServlet() {
        super();
    }

    protected void doGet(HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException {       
        String dataSourceName = null;

        dataSourceName = AppProperties.getDataSourceName();
    }
}

I deployed the web application MyWebProject on Tomcat. So under webapps folder of Tomcat, a new folder MyWebProject was created with all the necessary files. I then run the servlet http://localhost:8081/MyWebProject/AppPropertiesServlet and this is what appears on Tomcat console:

AppProperties: Name of classLoader = org.apache.catalina.loader.WebappClassLoader
AppProperties: propertiesFile = null

Why the propertiesFile is null? The app.properties file is in the WEB-INF\\lib folder of MyWebProject folder but somehow the classloader is unable to find it. Strange. What I am doing wrong here?

Thanks

Answer 1

If you want it to be under WEB-INF/lib it has to be packaged inside the JAR.

If you want it to be like a normal file , it has to be inside WEB-INF/classes .