Java Enum 範例 - enum HttpStatusCode

import java.util.EnumMap;
import java.util.HashMap;

/**
 * HttpStatusCode Enum and methods.
 * @author rock
 * @see /archives/10973291.html
 * @license GNU LGPL
 */
public enum HttpStatusCode {
    Ok(200),
    Not_Found(404),
    Error(500)
    ; // don't forget this.


    private int numeric;

    HttpStatusCode(int numeric) {
        this.numeric = numeric;
    }

    /**
     * numeric getter.
     * notice: you can not override ordinal()
     * assertEqual(200, HttpStatusCode.numeric("Ok"));
     */
    public int numeric() {
        return numeric;
    }

    /**
     * message getter.
     * assertEqual("Ok", HttpStatusCode.Ok.message());
     */
    public String message() {
        return toString();
    }

    private static EnumMap<HttpStatusCode, Integer> forward =
            new EnumMap<HttpStatusCode, Integer>(HttpStatusCode.class);
    private static HashMap<Integer, HttpStatusCode> reverse =
            new HashMap<Integer, HttpStatusCode>();

    static {
        HttpStatusCode[] values = HttpStatusCode.values();
        for (HttpStatusCode value : values) {
            forward.put(value, value.numeric());
            reverse.put(value.numeric(), value);
        }
    }

    /**
     * assertEqual(200, HttpStatusCode.Ok.numeric());
     */
    public static HttpStatusCode code(int numeric) {
        return reverse.get(numeric);
    }
    /**
     * assertEqual(HttpStatusCode.Ok, HttpStatusCode.code("Ok"));
     */
    public static HttpStatusCode code(String message) {
        return HttpStatusCode.valueOf(message);
    }
    /**
     * assertEqual(HttpStatusCode.Ok, HttpStatusCode.code(200));
     */
    public static int numeric(String message) {
        return forward.get( HttpStatusCode.valueOf(message) );
    }
    /**
     * 
     * assertEqual(200, HttpStatusCode.numeric(HttpStatusCode.Ok));
     */
    public static int numeric(HttpStatusCode code) {
        return code.numeric();
    }
    /**
     * assertEqual("Ok", HttpStatusCode.message(200));
     */
    public static String message(int numeric) {
        return code(numeric).message();
    }
    /**
     * assertEqual("Ok", HttpStatusCode.message(HttpStatusCode.Ok));
     */
    public static String message(HttpStatusCode code) {
        return code.message();
    }

}