在原图之上再画一张图片(drawImage)或者文本文字(drawString)，Java SE中提供了 java.awt.image包和javax.imageio包可以实现非常方便的实现 图片水印或者文字水印。

1.图片水印

import java.awt.AlphaComposite;

import java.awt.Graphics2D;

import java.awt.Image;

import java.awt.RenderingHints;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.FileOutputStream;

import java.io.OutputStream;

import javax.imageio.ImageIO;

import javax.swing.ImageIcon;

/**

* 生成图片水印

* @author Ricky Fung

*

*/

public class WaterMarkIconTest {

/**

* @param args

*/

public static void main(String[] args) {

File srcImageFile = new File("D:/test/myblog.png");

File logoImageFile = new File("D:/test/logo.png");

File outputImageFile = new File("D:/test/myblog_water_icon.jpg");

File outputRoateImageFile = new File("D:/test/myblog_water_icon_rotate.jpg");

createWaterMarkByIcon(srcImageFile, logoImageFile, outputImageFile);

createWaterMarkByIcon(srcImageFile, logoImageFile, outputRoateImageFile, 45);

}

public static void createWaterMarkByIcon(File srcImageFile, File logoImageFile,

File outputImageFile) {

createWaterMarkByIcon(srcImageFile, logoImageFile, outputImageFile, 0);

}

public static void createWaterMarkByIcon(File srcImageFile, File logoImageFile,

File outputImageFile, double degree) {

OutputStream os = null;

try {

Image srcImg = ImageIO.read(srcImageFile);

BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),

srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);

Graphics2D g = buffImg.createGraphics();

g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,

RenderingHints.VALUE_INTERPOLATION_BILINEAR);

g.drawImage(

srcImg.getScaledInstance(srcImg.getWidth(null),

srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0,

null);

ImageIcon logoImgIcon = new ImageIcon(ImageIO.read(logoImageFile));

Image logoImg = logoImgIcon.getImage();

//旋转

if (degree>0) {

g.rotate(Math.toRadians(degree),

(double) buffImg.getWidth() / 2,

(double) buffImg.getWidth() / 2);

}

float alpha = 0.8f; // 透明度

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,

alpha));

//水印 的位置

g.drawImage(logoImg, buffImg.getWidth()/3, buffImg.getHeight()/2, null);

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

g.dispose();

os = new FileOutputStream(outputImageFile);

// 生成图片

ImageIO.write(buffImg, "JPG", os);

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

if (null != os)

os.close();

} catch (Exception e) {

e.printStackTrace();

}

}

}

}

2.文字水印

import java.awt.AlphaComposite;

import java.awt.Color;

import java.awt.Font;

import java.awt.Graphics2D;

import java.awt.Image;

import java.awt.RenderingHints;

import java.awt.image.BufferedImage;

import java.io.File;

import java.io.FileOutputStream;

import java.io.OutputStream;

import javax.imageio.ImageIO;

/**

* 生成文字水印

* @author Ricky Fung

*

*/

public class WaterMarkTextTest {

/**

* @param args

*/

public static void main(String[] args) {

File srcImgFile = new File("D:/test/myblog.png");

String logoText = "[ 水印文字 电话邦 ]";

File outputImageFile = new File("D:/test/myblog_water_text.jpg");

File outputRotateImageFile = new File("D:/test/myblog_water_text_rotate.jpg");

createWaterMarkByText(srcImgFile, logoText, outputImageFile);

createWaterMarkByText(srcImgFile, logoText, outputRotateImageFile, 45);

}

public static void createWaterMarkByText(File srcImgFile, String logoText,

File outputImageFile) {

createWaterMarkByText(srcImgFile, logoText, outputImageFile, 0);

}

public static void createWaterMarkByText(File srcImgFile, String logoText,

File outputImageFile, double degree) {

OutputStream os = null;

try {

Image srcImg = ImageIO.read(srcImgFile);

BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),

srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);

Graphics2D g = buffImg.createGraphics();

g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,

RenderingHints.VALUE_INTERPOLATION_BILINEAR);

g.drawImage(

srcImg.getScaledInstance(srcImg.getWidth(null),

srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0,

null);

if (degree>0) {

g.rotate(Math.toRadians(degree),

(double) buffImg.getWidth() / 2,

(double) buffImg.getHeight() / 2);

}

g.setColor(Color.RED);

g.setFont(new Font("宋体", Font.BOLD, 36));

float alpha = 0.8f;

g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,

alpha));

g.drawString(logoText, buffImg.getWidth()/3, buffImg.getHeight()/2);

g.dispose();

os = new FileOutputStream(outputImageFile);

// 生成图片

ImageIO.write(buffImg, "JPG", os);

} catch (Exception e) {

e.printStackTrace();

} finally {

try {

if (null != os)

os.close();

} catch (Exception e) {

e.printStackTrace();

}

}

}

}