How to parse the templated sentence "#{name} invited you" using expression language

I am a new bee to Java.

My intension is to use the template like sentences in Java program (no JSP or any web related pages)

Example:

String name = "Jon";

"#{ name } invited you";

      or 

 String user.name = "Jon";

 "#{ user.name } invited you";

If I pass 开发者_如何学JAVAthis string to some method, I should get

"Jon invited you"

I've gone through some expression languages MVEL, OGNL, JSTL EL

In MVEL and OGNL, I have to write some set of code to achieve this but in some other way.

I can achieve this using JSTL EL only in JSP files not in java program.

Is there any way to achieve this?

Thanks in advance.

Jon

Is there any way to achieve this?

I'm not 100% sure I understand what you're after, but here are some pointers...

Have a look at the MessageFormat class in the API. You may also be interested in the Formatter class and/or the String.format method.

If you have some Properties and you want to search and replace substrings of the shape #{ property.key } you could also just do like this:

import java.util.Properties;
import java.util.regex.*;

class Test {

    public static String process(String template, Properties props) {
        Matcher m = Pattern.compile("#\\{(.*?)\\}").matcher(template);

        StringBuffer sb = new StringBuffer();
        while (m.find())
            m.appendReplacement(sb, props.getProperty(m.group(1).trim()));
        m.appendTail(sb);

        return sb.toString();
    }


    public static void main(String[] args) {
        Properties props = new Properties();
        props.put("user.name", "Jon");
        props.put("user.email", "jon.doe@example.com");

        String template = "Name: #{ user.name }, email: #{ user.email }";

        // Prints "Name: Jon, email: jon.doe@example.com"
        System.out.println(process(template, props));
    }
}

If you have actual POJOs and not a Properties object, you could go through reflection, like this:

import java.util.regex.*;

class User {
    String name;
    String email;
}


class Test {

    public static String process(String template, User user) throws Exception {
        Matcher m = Pattern.compile("#\\{(.*?)\\}").matcher(template);

        StringBuffer sb = new StringBuffer();
        while (m.find()) {
            String fieldId = m.group(1).trim();
            Object val = User.class.getDeclaredField(fieldId).get(user);
            m.appendReplacement(sb, String.valueOf(val));
        }
        m.appendTail(sb);
        return sb.toString();
    }


    public static void main(String[] args) throws Exception {
        User user = new User();
        user.name = "Jon";
        user.email = "jon.doe@example.com";
        String template = "Name: #{ name }, email: #{ email }";

        System.out.println(process(template, user));
    }
}

... but it's getting ugly, and I suggest you consider digging deeper into some of the 3rd party libraries for solving this.