public class CreateImage {
	public static void main(String[] args) throws Exception{
		int width = 100;   
        int height = 100;   
        String s = "你好";   
           
        File file = new File("/Users/tengxin/Pictures/image.jpg");   
           
        Font font = new Font("Serif", Font.BOLD, 10);   
        BufferedImage bi = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);   
        Graphics2D g2 = (Graphics2D)bi.getGraphics();   
        g2.setBackground(Color.WHITE);   
        g2.clearRect(0, 0, width, height);   
        g2.setPaint(Color.RED);   
           
        FontRenderContext context = g2.getFontRenderContext();   
        Rectangle2D bounds = font.getStringBounds(s, context);   
        double x = (width - bounds.getWidth()) / 2;   
        double y = (height - bounds.getHeight()) / 2;   
        double ascent = -bounds.getY();   
        double baseY = y + ascent;   
           
        g2.drawString(s, (int)x, (int)baseY);   
           
        ImageIO.write(bi, "jpg", file);    
	}
}

java生成一张图片