给图片加水印的主要步骤包括：

1、获取原图的画笔

2、设置水印信息、水印位置

3、在原图上画出水印

工具代码

/**

* 在图片右下角添加白色文字水印

* @param is

* @param os

* @param text

* @throws IOException

*/

public static void makeWatermark(InputStream is, OutputStream os, String text, String format) throws IOException {

BufferedImage image = ImageIO.read(is);

if (image != null) {

int width = image.getWidth();

int height = image.getHeight();

//计算字体大小

int fontSize = (int)(width * height * 0.000008 + 13);

Font font = new Font("宋体", Font.PLAIN, fontSize);

Graphics2D g = image.createGraphics();

g.setFont(font);

g.setColor(Color.white); //水印颜色-白色

透明度

//float alpha = 0.9f;

//g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));

int x = width - getWatermarkLength(text, g) - 10;

x = x < 0 ? 0 : x;

int y = height - 10;

y = y < 0 ? 0 : y;

//对线段的锯齿状边缘处理

g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,RenderingHints.VALUE_INTERPOLATION_BILINEAR);

g.drawString(text, x, y);

g.dispose();

ImageIO.write(image, format, os);

}

}

/**

* 获取水印文字总长度

* @param text 水印的文字

* @param g

* @return 水印文字总长度

*/

private static int getWatermarkLength(String text, Graphics g) {

return g.getFontMetrics(g.getFont()).charsWidth(

text.toCharArray(), 0, text.length());

}

测试代码

/**

* 测试制作水印

* @throws IOException

* @throws FileNotFoundException

*/

@Test

public void testMakeWatermark() throws FileNotFoundException, IOException {

String imageName = "java_coffee.jpg";

String srcPath = IMAGE_PATH + imageName;

imageName = "java_coffee_wm.jpg";

String detsPath = IMAGE_PATH + imageName;

ImageUtil.makeWatermark(new FileInputStream(srcPath),

new FileOutputStream(detsPath), "测试水印", "jpg");

}

效果图

标签：java,String,int,text,image,水印,param,加水

来源： https://blog.csdn.net/meism5/article/details/88861835