给图片添加水印【png格式添加水印后背景保持透明】

package com.solex.waterPrint;

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.Transparency;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.InputStream;
import java.io.OutputStream;
import java.text.SimpleDateFormat;
import java.util.Calendar;
import java.util.Date;

import javax.imageio.ImageIO;
import javax.swing.ImageIcon;

public class TestWaterPic {

public static void main(String[] args) {
String iconPath="C:/Users/solexit06/Desktop/temp/logo.png";//作为水印的图片
String targerPath1 = "C:/Users/solexit06/Desktop/sj01.png";//添加水印后保持路径
String srcImgPath = "C:/Users/solexit06/Desktop/temp/sj.png";//需要加水印的源图片
String targerPath2 = "C:/Users/solexit06/Desktop/sj02.png";//添加水印后保持路径

Date date=Calendar.getInstance().getTime();
SimpleDateFormat sdf=new SimpleDateFormat("yyyy-MM-dd");
String dateStr=sdf.format(date);

TestWaterPic.markImageByIcon(iconPath, srcImgPath, targerPath1); // 给图片添加水印
TestWaterPic.waterMarkByText(dateStr, srcImgPath, targerPath2, 0, 180, 133, 1.0f);//给图片添加文字水印
}

/**
* 给图片添加“图片水印”
* @param iconPath 作为水印的图片路径
* @param srcImgPath 源图片路径
* @param targerPath 目标图片路径
*/
public static void markImageByIcon(String iconPath, String srcImgPath,String targerPath) {
markImageByIcon(iconPath, srcImgPath, targerPath, null);
}

/**
* 给图片添加“图片水印”、可设置图片水印旋转角度
* @param iconPath 作为水印的图片路径
* @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
*/
public static void markImageByIcon(String iconPath, String srcImgPath,String targerPath, Integer degree) {
OutputStream os = null;
try {
//1、源图片
Image srcImg = ImageIO.read(new File(srcImgPath));
BufferedImage buffImg = new BufferedImage(
srcImg.getWidth(null),srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);

//2、水印图象：水印一般为gif或者png的，这样可设置透明度
ImageIcon imgIcon = new ImageIcon(iconPath);
Image img = imgIcon.getImage();// 得到Image对象。

//3、画笔对象
Graphics2D g2d = buffImg.createGraphics();
// ----------  增加下面的代码使得背景透明  -----------------
buffImg = g2d.getDeviceConfiguration().createCompatibleImage(
srcImg.getWidth(null),srcImg.getHeight(null),Transparency.TRANSLUCENT);
g2d.dispose();
g2d = buffImg.createGraphics();
// ----------  背景透明代码结束  -----------------

// 设置对线段的锯齿状边缘处理
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);// 设置对线段的锯齿状边缘处理

g2d.drawImage(srcImg.getScaledInstance(srcImg.getWidth(null),
srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0, null);

// 设置水印旋转
if (null != degree) {
g2d.rotate(Math.toRadians(degree),(double) buffImg.getWidth()/2,
(double) buffImg.getHeight()/2);
}

// 透明度
float alpha = 1.0f;
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,alpha));
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));

// 表示水印图片的位置
g2d.drawImage(img, 90, 92, null);

//4、释放资源
g2d.dispose();

//5、生成图片
os = new FileOutputStream(targerPath);
ImageIO.write(buffImg,"PNG",os);

System.out.println("图片完成添加Icon印章");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (null != os)
os.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}

/**
* 给图片添加“文字水印”、可设置旋转角度
* @param logoText水印文字
* @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 width宽度(与左相比)
* @param height高度(与顶相比)
* @param clarity透明度(小于1的数)越接近0越透明
*/
public static void waterMarkByText(String logoText, String srcImgPath,
String targerPath, Integer degree, Integer width, Integer height,
Float clarity) {

InputStream is = null;
OutputStream os = null;
try {
/**1、源图片*/
Image srcImg = ImageIO.read(new File(srcImgPath));
//创建BufferedImage对象:new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
//其实就是以源图片的宽度为宽，以源图片的长度为长
BufferedImage buffImg = new BufferedImage(srcImg.getWidth(null),
srcImg.getHeight(null), BufferedImage.TYPE_INT_RGB);

/**2、得到画笔对象*/
Graphics2D g2d = buffImg.createGraphics();

// ----------  增加下面的代码使得背景透明  -----------------
buffImg = g2d.getDeviceConfiguration().createCompatibleImage(
srcImg.getWidth(null),srcImg.getHeight(null),Transparency.TRANSLUCENT);
g2d.dispose();
g2d = buffImg.createGraphics();
// ----------  背景透明代码结束  -----------------

// 设置对线段的锯齿状边缘处理
g2d.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);

//把源图片写入
g2d.drawImage(srcImg.getScaledInstance(srcImg.getWidth(null),
srcImg.getHeight(null), Image.SCALE_SMOOTH), 0, 0,null);

// 设置水印旋转
if (null != degree) {g2d.rotate(Math.toRadians(degree),(double) buffImg.getWidth() / 2,
(double) buffImg.getHeight() / 2);
}

// 设置颜色
g2d.setColor(Color.red);

// 设置 Font
g2d.setFont(new Font("微软雅黑", Font.ROMAN_BASELINE, 33));

//设置透明度:1.0f为透明度 ，值从0-1.0，依次变得不透明
float alpha = clarity;
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,alpha));
g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));//透明度设置 结束
//文字内容，文字在图片上的坐标位置(x,y)
g2d.drawString(logoText, width, height);

//释放资源
g2d .dispose();

/**3、生成图片*/
os = new FileOutputStream(targerPath);
ImageIO.write(buffImg, "png", os);

System.out.println("添加水印文字完成!");
} catch (Exception e) {
e.printStackTrace();
} finally {
try {
if (null != os)
os.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}
}

http://blog.csdn.net/beinlife/article/details/53665152