Exception occurred during processing request: null异常！求大神来看看，代码，异常都贴上了

Exception occurred during processing request: null错误！求大神来看看，代码，错误都贴上了~
报错的代码

public void addMusic(Music music){
		conn = DBUtil.getCon();
		String sql = "insert into tb_music(musicName,singer,size) values(?,?,?)";
		try {
			ps = conn.prepareStatement(sql);
			ps.setString(1, music.getMusicName());
			ps.setString(2, music.getSinger());
			ps.setString(3, music.getSize());
			ps.executeUpdate();
		} catch (SQLException e) {
			e.printStackTrace();
		} finally {

			DBUtil.closeStatement(ps);
			DBUtil.closeCon(conn);
		}		
	}

	public String addMusic(){
		musicDao.addMusic(music);
		return	"musicQuerySuccess";	
	}

------解决思路----------------------
错误很明显，music 没有值