在采用Java进行网站开发时，为了网站上面添加版权方面的信息，避免被他人非法使用。经常需要在图片上面添加水印，下面我们使用java来给图片添加水印。
实现原理：
这里的水印是一张小图片，我们将水印小图片绘制到目标大图片上面。
代码如下：
package com.bug315;
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;
/**
* 图片处理工具类
* @author huangxin
*
*/
public class ImageTools {
/**
* 水印的位置
*/
public static final int LEFT_TOP = 0x0;
public static final int LEFT_CENTER = 0x1;
public static final int LEFT_BOTTOM = 0x2;
public static final int RIGHT_TOP = 0x3;
public static final int RIGHT_CENTER = 0x4;
public static final int RIGHT_BOTTOM = 0x5;
public static final int TOP_CENTER = 0x6;
public static final int BOTTOM_CENTER = 0x7;
public static final int CENTER = 0x8;
/**
* 给图片添加水印
*
* @param iconPath 水印图片路径
* @param srcImgPath 源图片路径
* @param targerPath 目标图片路径
* @param position 水印图片路径，见ImageTools的常量
* @param alpha 水印图片的透明度
*/
public static void markImageByIcon(String iconPath, String srcImgPath,
String targerPath, int position, float alpha) {
markImageByIcon(iconPath, srcImgPath, targerPath, -1, position, alpha);
}
/**
* 给图片添加水印、可设置水印图片旋转角度
*
* @param iconPath 水印图片路径
* @param srcImgPath 源图片路径
* @param targerPath 目标图片路径
* @param degree 水印图片旋转角度
* @param position 水印图片路径，见ImageTools的常量
* @param alpha 水印图片的透明度
*/
public static void markImageByIcon(String iconPath, String srcImgPath,
String targerPath, int degree, int position, float alpha) {
OutputStream outputStream = null;
try {
Image srcImgObj = ImageIO.read(new File(srcImgPath));
BufferedImage bufferedSrcImgObj = new BufferedImage(srcImgObj.getWidth(null),
srcImgObj.getHeight(null), BufferedImage.TYPE_INT_RGB);
// 得到画笔对象
Graphics2D graphic = bufferedSrcImgObj.createGraphics();
// 设置对线段的锯齿状边缘处理
graphic.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR );
graphic.drawImage(
srcImgObj.getScaledInstance(srcImgObj.getWidth(null),
srcImgObj.getHeight(null), Image.SCALE_SMOOTH), 0, 0, null);
/**
* 设置水印旋转
*/
if ( -1 != degree ) {
graphic.rotate(Math.toRadians(degree),
(double) bufferedSrcImgObj.getWidth() / 2,
(double) bufferedSrcImgObj.getHeight() / 2 );
}
// 水印图象的路径 水印一般为gif或者png的，这样可设置透明度
ImageIcon iconImageIconObj = new ImageIcon(iconPath);
Image iconImageObj = iconImageIconObj.getImage();
/**
* 设置水印图片的透明度
*/
if ( alpha >= 0 && alpha <= 1) {
graphic.setComposite(
AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, alpha));
}
/**
* 水印图片的大小
*/
int iconHeight = iconImageObj.getHeight(null);
int iconWidth = iconImageObj.getWidth(null);
while ( bufferedSrcImgObj.getWidth(null) < iconWidth ) {
iconWidth = (int)(iconWidth * 0.8);
iconHeight = (int)(iconHeight * 0.8);
}
while ( bufferedSrcImgObj.getHeight(null) < iconHeight ) {
iconWidth = (int)(iconWidth * 0.8);
iconHeight = (int)(iconHeight * 0.8);
}
/**
* 设置水印图片的位置
*/
int xPosition = 0, yPosition = 0;
switch ( position ) {
case LEFT_TOP:
xPosition = 0;
yPosition = 0;
break;
case LEFT_CENTER:
xPosition = 0;
yPosition = (srcImgObj.getHeight(null) - iconHeight) / 2;
break;
case LEFT_BOTTOM:
xPosition = 0;
yPosition = (srcImgObj.getHeight(null) - iconHeight);
break;
case RIGHT_TOP:
xPosition = (srcImgObj.getWidth(null) - iconWidth);
yPosition = 0;
break;
case RIGHT_CENTER:
xPosition = (srcImgObj.getWidth(null) - iconWidth);
yPosition = (srcImgObj.getHeight(null) - iconHeight) / 2;
break;
case RIGHT_BOTTOM:
xPosition = (srcImgObj.getWidth(null) - iconWidth);
yPosition = (srcImgObj.getHeight(null) - iconHeight);
break;
case TOP_CENTER:
xPosition = (srcImgObj.getWidth(null) - iconWidth) / 2;
yPosition = 0;
break;
case BOTTOM_CENTER:
xPosition = (srcImgObj.getWidth(null) - iconWidth) / 2;
yPosition = (srcImgObj.getHeight(null) - iconHeight);
break;
case CENTER:
xPosition = (srcImgObj.getWidth(null) - iconWidth) / 2;
yPosition = (srcImgObj.getHeight(null) - iconHeight)/2;
break;
}
graphic.drawImage(iconImageObj, xPosition, yPosition, iconWidth, iconHeight, null);
graphic.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
graphic.dispose();
/**
* 生成图片
*/
outputStream = new FileOutputStream(targerPath);
ImageIO.write(bufferedSrcImgObj, "JPG", outputStream);
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if ( null != outputStream ) {
outputStream.close();
outputStream = null;
}
} catch (Exception e) {
e.printStackTrace();
}
}
} //
}客户端代码：
public class Test02 {
public static void main(String[] args) {
String iconPath = "img/icon2.png";
String srcImgPath = "img/img_12.png";
String distImgPath = "img/dist_img_12.png";
ImageTools.markImageByIcon(iconPath, srcImgPath, distImgPath,
ImageTools.CENTER, 1.0F);
}
}
