jndihelper.java

jsp版 音乐站点 j2ee+weblogic

package music.ejb; 

import java.rmi.RemoteException;
import java.util.*;
import javax.naming.*;
import javax.servlet.jsp.JspException;

import music.ejb.db.*;

/**
 * JndiHelper使Session Bean能够方便地调用Entity Bean
 */
public class JndiHelper {

    private static Object syn = new Object();

    // for local home:
    private static final String CATEGORY = "ejb/Category";
    private static final String ARTIST = "ejb/Artist";
    private static final String ALBUM = "ejb/Album";
    private static final String SONG = "ejb/Song";
    private static final String ACCOUNT = "ejb/Account";

    // for local home:
    private static CategoryLocalHome category = null;
    private static ArtistLocalHome artist = null;
    private static AlbumLocalHome album = null;
    private static SongLocalHome song = null;
    private static AccountLocalHome account = null;

    private static Object lookup(String jndi) {
        Hashtable ht = new Hashtable();
        ht.put(Context.INITIAL_CONTEXT_FACTORY, "weblogic.jndi.WLInitialContextFactory");
        ht.put(Context.PROVIDER_URL, "t3://localhost:7001");
        Context ctx = null;
        Object obj = null;
        try {
            ctx = new InitialContext(ht);
            obj = ctx.lookup(jndi);
        }
        catch(NamingException ne) {
            // Error log:
            System.out.println("-- Exception in static JndiHelper.lookup(" + jndi + ") --");
            ne.printStackTrace();
        }
        finally {
            try { ctx.close(); } catch(Exception e) {}
        }
        return obj;
    }

    public static CategoryLocalHome getCategoryLocalHome() {
        if (category==null) {
            synchronized(syn) {
                category = (CategoryLocalHome)lookup(CATEGORY);
            }
        }
        return category;
    }

    public static ArtistLocalHome getArtistLocalHome() {
        if (artist==null) {
            synchronized(syn) {
                artist = (ArtistLocalHome)lookup(ARTIST);
            }
        }
        return artist;
    }

    public static AlbumLocalHome getAlbumLocalHome() {
        if (album==null) {
            synchronized(syn) {
                album = (AlbumLocalHome)lookup(ALBUM);
            }
        }
        return album;
    }

    public static SongLocalHome getSongLocalHome() {
        if (song==null) {
            synchronized(syn) {
                song = (SongLocalHome)lookup(SONG);
            }
        }
        return song;
    }

    public static AccountLocalHome getAccountLocalHome() {
        if (account==null) {
            synchronized(syn) {
                account = (AccountLocalHome)lookup(ACCOUNT);
            }
        }
        return account;
    }

}