Java图片处理（二）图片加水印

图片加水印，是通过图片重叠绘制实现的。实现代码如下：
public static void press(String pressImg, String pressText, String targetImg,
String fontName, int fontStyle, int color, int fontSize, int x, int y) {
try {
File _file = new File(targetImg);
Image src = ImageIO.read(_file);
int wideth = src.getWidth(null);
int height = src.getHeight(null);
BufferedImage image = new BufferedImage(wideth, height,
BufferedImage.TYPE_INT_RGB);
Graphics2D g = image.createGraphics();
g.drawImage(src, 0, 0, wideth, height, null);
g.setColor(new Color(255, 255, 255, 80));
g.setFont(new Font(fontName, fontStyle, fontSize));

g.drawString(pressText, wideth - fontSize - x, height - fontSize / 2 - y);

//水印文件
File _filebiao = new File(pressImg);
Image src_biao = ImageIO.read(_filebiao);

int wideth_biao = src_biao.getWidth(null);
int height_biao = src_biao.getHeight(null);

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 0.4f));

g.drawImage(src_biao, (wideth - wideth_biao) / 2,
height - fontSize / 2 - 50, wideth_biao/2-10, height_biao/2-10, null);

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));

g.dispose();
FileOutputStream out = new FileOutputStream(targetImg);
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
encoder.encode(image);
out.close();
} catch (Exception e) {
System.out.println(e);
}
}

图片设置透明度
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, 0.4f));

g.drawImage(src_biao, (wideth - wideth_biao) / 2,
height - fontSize / 2 - 50, wideth_biao/2-10, height_biao/2-10, null);

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));

文字设置透明度
文字的透明度由颜色决定，因此只需要设置颜色的RGBA即可。如下：
Graphics2D g = image.createGraphics();
g.drawImage(src, 0, 0, wideth, height, null);
g.setColor(new Color(255, 255, 255, 80));
g.setFont(new Font(fontName, fontStyle, fontSize));

g.drawString(pressText, wideth - fontSize - x, height - fontSize/ 2 - y);