musicview.ejb

J2EE的一个开发实例

package music.ejb;

import java.io.*;
import java.util.*;
import javax.ejb.*;
import weblogic.ejb.*;

import music.ejb.db.*;
import music.shared.*;

/**
 * @ejbgen:session default-transaction="Required" type="Stateless"
 *   ejb-name = "MusicView"
 *
 * @ejbgen:jndi-name remote="ejb/MusicView"
 *
 * @ejbgen:file-generation remote-class="true" remote-class-name = "MusicViewRemote" remote-home="true" remote-home-name="MusicViewRemoteHome" local-class="true" local-class-name = "MusicViewLocal" local-home="true" local-home-name = "MusicViewLocalHome"
 */
public class MusicView
  extends GenericSessionBean
  implements SessionBean
{
  public void ejbCreate() {
    // Your code here
  }

    /**
     * @ejbgen:remote-method
     */
    public Collection getCategories(int parentId)
        throws IllegalArgumentException
    {
        Collection c = null;
        try {
            c = JndiHelper.getCategoryLocalHome().findByParentId(parentId);
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such parent category with id = " + parentId);
        }
        Iterator it = c.iterator();
        Collection ret = new ArrayList();
        while(it.hasNext()) {
            ret.add(((CategoryLocal)it.next()).copy());
        }
        return ret;
    }

    /**
     * @ejbgen:remote-method
     */
    public Collection getArtists(int categoryId)
        throws IllegalArgumentException
    {
        // first find out the category:
        CategoryLocalHome categoryHome = JndiHelper.getCategoryLocalHome();
        CategoryLocal local = null;
        try {
            local = categoryHome.findByPrimaryKey(new Integer(categoryId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such category with id " + categoryId);
        }
        Iterator it = local.getArtists().iterator();
        Collection ret = new ArrayList();
        while(it.hasNext()) {
            ret.add(((ArtistLocal)it.next()).copy());
        }
        return ret;
    }

    /**
     * 返回指定艺术家的所有专辑集合，类型为AlbumVO
     * @param artistId 指定艺术家的ID
     * @throw IllegalArgumentException 指定的艺术家不存在
     * @ejbgen:remote-method
     */
    public Collection getAlbums(int artistId)
        throws IllegalArgumentException
    {
        ArtistLocal artist = null;
        try {
            artist = JndiHelper.getArtistLocalHome().findByPrimaryKey(new Integer(artistId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such artist with id " + artistId);
        }
        Iterator it = artist.getAlbums().iterator();
        Collection ret = new ArrayList();
        while(it.hasNext()) {
            ret.add(((AlbumLocal)it.next()).copy());
        }
        return ret;
    }

    /**
     * @ejbgen:remote-method
     */
    public Collection getSongs(int albumId)
        throws IllegalArgumentException
    {
        AlbumLocal album = null;
        try {
            album = JndiHelper.getAlbumLocalHome().findByPrimaryKey(new Integer(albumId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such album with id " + albumId);
        }
        Iterator it = album.getSongs().iterator();
        Collection ret = new ArrayList();
        while(it.hasNext()) {
            ret.add(((SongLocal)it.next()).copy());
        }
        return ret;
    }

    /**
     * @ejbgen:remote-method
     */
    public String getLyric(int songId)
        throws IllegalArgumentException, LyricNotFoundException
    {
        SongLocal song = null;
        try {
            song = JndiHelper.getSongLocalHome().findByPrimaryKey(new Integer(songId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such song with id " + songId);
        }
        if(!song.hasLyric())
            throw new LyricNotFoundException("No lyric of this song.");
        return song.getLyric();
    }

    /**
     * @ejbgen:remote-method
     */
    public int rate(int songId, int mark) throws IllegalArgumentException
    {
        SongLocal song = null;
        try {
            song = JndiHelper.getSongLocalHome().findByPrimaryKey(new Integer(songId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such song with id " + songId);
        }
        return song.rate(mark);
    }

    /**
     * 返回对应的文件路径，例如:
     * /pop/english/female/dido/no angel/thank you.mp3
     * 如果song.hasUrl()==false, throw FileNotFoundException
     * @ejbgen:remote-method
     */
    public String download(int songId)
        throws IllegalArgumentException, FileNotFoundException
    {
        SongLocal song = null;
        try {
            song = JndiHelper.getSongLocalHome().findByPrimaryKey(new Integer(songId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such song with id " + songId);
        }
        // then get the file:
        if(!song.hasUrl())
            throw new FileNotFoundException("No file associated with this song.");

        return song.getUrl();
    }

    /**
     * @ejbgen:remote-method
     */
    public Collection searchSongs(String title)
        throws IllegalArgumentException
    {
        if(title==null)
            throw new IllegalArgumentException("Title is NULL.");
        title = title.trim().toLowerCase();
        if(title.equals(""))
            throw new IllegalArgumentException("Title is EMPTY.");
        try {
            Collection c = JndiHelper.getSongLocalHome().findByTitle(title);
            Collection ret = new ArrayList(c.size());
            Iterator it = c.iterator();
            while(it.hasNext())
                ret.add(((SongLocal)it.next()).copy());
            return ret;
        }
        catch(FinderException fe) {}
        return new ArrayList();
    }

    /**
     * @ejbgen:remote-method
     */
    public Collection getCategoryFullPath(int categoryId)
        throws IllegalArgumentException
    {
        CategoryLocal category = null;
        try {
            category = JndiHelper.getCategoryLocalHome().findByPrimaryKey(new Integer(categoryId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such category with id " + categoryId);
        }
        return category.fullPath();
    }

    /**
     * @ejbgen:remote-method
     */
    public ArtistVO getArtist(int albumId)
        throws IllegalArgumentException
    {
        AlbumLocal album = null;
        try {
            album = JndiHelper.getAlbumLocalHome().findByPrimaryKey(new Integer(albumId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such album with id " + albumId);
        }
        return album.getArtist().copy();
    }

    /**
     * @ejbgen:remote-method
     */
    public AlbumVO getAlbum(int songId)
        throws IllegalArgumentException
    {
        SongLocal song = null;
        try {
            song = JndiHelper.getSongLocalHome().findByPrimaryKey(new Integer(songId));
        }
        catch(FinderException fe) {
            throw new IllegalArgumentException("No such song with id " + songId);
        }
        return song.getAlbum().copy();
    }
}