It is not really clear how it came to pass that glass beads were made in Java quite a few centuries ago. However, two factors that must be considered are these: 1) Tamil glass-beadmakers introduced the practice of making Indo-Pacific beads (small drawn monochromatic beads that became locally known as mutisalah beads when red or orange); and 2) Middle Eastern beads that were destined for China passed through Indonesia on their way there (once sea routes were established). The stylistic and technical connections between Middle Eastern and Javanese mosaic-glass are undeniable.

The importance of Chinese glass-beadmaking is easy to overestimate, because of the quantities they made in modern times (from the Ming Dynasty on). But glass was not an important product in China, was only introduced in the Warring States Period, and began to become degraded by the Han Dynasty. From the Han to the Ming, there is not a lot of glasswork, and practically no conventional beads. (Most glass was worked via lapidary techniques, like a stone.)

I don't see any connection between Indonesian glass beads and Chinese beads. The glass is different, the way the beads were made is different, and the Chinese basically were not in the glass game at the times Javanese beads were made. A more likely connection was between Indian and Middle Eastern beadmakers.

Jamey