Java实现水印功能
一，水印功能，
就是在图片上加上某个标示性的图片，起到宣传作用；一般常见于论坛的上传图片，在上传的图片中某个位置加上自家网站水印标示图，起到很好的宣传作用；
Java实现水印功能很多，因需要自己实现了一个，完成了写到博客中，方便日后使用，懒人计划....
二，实现步骤，
1，实现原理
* Theory/原理:
* 1,建立一个画布,设置其边线纹理处理方式;再其上根据原图尺寸画上原图;
* 2,再设置透明值,计算水印图位置,再在画布的指定位置画上指定大小的水印图;
* 3,然后混合和处理画布中的图片数据,最后输出到指定目标图片文件;
2，实现代码，
public static void addWaterMark(String _srcImagePath, String _targetImagePath,
String _iconImagePath, String _iconPosition, Float _iconAlpha,
Integer _targetIconWidth, Integer _targetIconHeight) {
/**
* Theory/原理:
* 1,建立一个画布,设置其边线纹理处理方式;再其上根据原图尺寸画上原图;
* 2,再设置透明值,计算水印图位置,再在画布的指定位置画上指定大小的水印图;
* 3,然后混合和处理画布中的图片数据,最后输出到指定目标图片文件;
* @auther: shenzhenNBA
* @param _srcImagePath is absolute path of source image which need to add water mark, required;
* @param _targetImagePath is absolute path of target image which will be
* contains water mark icon image, if empty then will save to source image, optional;
*
* @param _iconImagePath is absolute path of water mark icon image, required;
* @param _iconPosition is position of water mark icon in source image, optional and
* default position is bottom right, value is one of [topLeft,topRight,bottomLeft,bottomRight];
* @param _iconAlpha is to set alpha value of water mark icon image, optional;
* @param _targetIconWidth is width of target water mark icon image, optional;
* @param _targetIconHeight is height of target water mark icon image, optional;
*
* usage (example):
* CommonFunService.addWaterMark(
* "c:\path\srcImage.jpg"
* ,"c:\path\targetImage.gif"
* ,"c:\path\iconImage.png"
* ,"bottomright"
* ,new Float(0.8)
* ,0
* ,0
* );
*/
if(null != _srcImagePath && !_srcImagePath.trim().isEmpty()
&& null != _iconImagePath && !_iconImagePath.trim().isEmpty()){
String srcImagePath = _srcImagePath.trim();
String targetImagePath = "";
String iconImagePath = _iconImagePath.trim();
String iconPosition = "";
Integer targetIconWidth = 0;
Integer targetIconHeight = 0;
Integer imgIconAxisX = 0;
Integer imgIconAxisY = 0;
Integer imgIconMargin = 5;
Float iconAlpha = 0.8f;
if(null == _targetImagePath || _targetImagePath.trim().isEmpty()){
targetImagePath = srcImagePath;
}else{
targetImagePath = _targetImagePath.trim();
}
if(null == _iconPosition || _iconPosition.trim().isEmpty()){
iconPosition = "bottomRight";
}else{
iconPosition = _iconPosition.trim();
}
if(null == _iconAlpha){
iconAlpha = 0.8f;
}
if(null != _iconAlpha && _iconAlpha < 0){
iconAlpha = 0.1f;
}
OutputStream os = null;
try {
//read and get image data base on parameter
Image srcImg = ImageIO.read(new File(srcImagePath));
Integer srcImgWidth = srcImg.getWidth(null);
Integer srcImgHeight = srcImg.getHeight(null);
BufferedImage buffImg = new BufferedImage(srcImgWidth,
srcImgHeight, BufferedImage.TYPE_INT_RGB);
// create or get the canvas of buffer image,创建或得到画布对象
// Graphics g= buffImg.getGraphics();
Graphics2D g = buffImg.createGraphics();
// set the sawtooth style of line, 设置对线段的锯齿状边缘处理
g.setRenderingHint(RenderingHints.KEY_INTERPOLATION,
RenderingHints.VALUE_INTERPOLATION_BILINEAR);
g.drawImage(srcImg.getScaledInstance(srcImgWidth,
srcImgHeight, Image.SCALE_SMOOTH), 0, 0, null);
/*
//----------------------------------------------------
// set the rotate of icon image,no active, 设置水印图的旋转,未启用,
if (null != degree) {
g.rotate(Math.toRadians(degree),
(double) buffImg.getWidth() / 2,
(double) buffImg.getHeight() / 2);
}
//----------------------------------------------------
*/
// read icon image base on parameter, it should be gif or png file normally as which can set alpha
// 读取水印图象,水印图一般为gif或者png的,这样可设置透明度
// read and get icon image data, width and height ,读取Image数据对象,宽和高
Image imgIcon = ImageIO.read(new File(iconImagePath));
Integer imgIconWidth = imgIcon.getWidth(null);
Integer imgIconHeight = imgIcon.getHeight(null);
if(null == _targetIconWidth){
targetIconWidth = imgIconWidth;
}else{
targetIconWidth = _targetIconWidth;
}
if(targetIconWidth <= 0){
targetIconWidth = imgIconWidth;
}
if(null == _targetIconHeight){
targetIconHeight = imgIconHeight;
}else{
targetIconHeight = _targetIconHeight;
}
if(targetIconHeight <= 0){
targetIconHeight = imgIconHeight;
}
Image targetIconImage = imgIcon.getScaledInstance(targetIconWidth,
targetIconHeight, Image.SCALE_SMOOTH);
// set icon image position in source image,设置水印图片印在原图中的位置
if("bottomRight".equalsIgnoreCase(iconPosition)){
imgIconAxisX = srcImgWidth - targetIconWidth - imgIconMargin;
imgIconAxisY= srcImgHeight - targetIconHeight - imgIconMargin;
}else if("bottomLeft".equalsIgnoreCase(iconPosition)){
imgIconAxisX = imgIconMargin;
imgIconAxisY= srcImgHeight - targetIconHeight - imgIconMargin;
}else if("topRight".equalsIgnoreCase(iconPosition)){
imgIconAxisX = srcImgWidth - targetIconWidth - imgIconMargin;
imgIconAxisY= imgIconMargin;
}else{//topLeft
imgIconAxisX = imgIconMargin;
imgIconAxisY= imgIconMargin;
}
if(imgIconAxisX < 0){
imgIconAxisX = (Integer)(srcImgWidth / 2);
}
if(imgIconAxisY < 0){
imgIconAxisX = (Integer)(srcImgHeight / 2);
}
// set the alpha to icon image,设置水印图的透明度
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, iconAlpha));
//draw the target icon image at target position width target size in source image
//在原图中指定位置绘制指定大小的水印图
g.drawImage(targetIconImage, imgIconAxisX, imgIconAxisY, null);
g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));
g.dispose();
// create target image which containers icon image,
// 生成含有在指定位置指定大小加了水印图的新图片
os = new FileOutputStream(targetImagePath);
ImageIO.write(buffImg, "JPG", os);
//release system source
srcImg = null;
//imageIcon = null;
imgIcon = null;
targetIconImage = null;
buffImg = null;
g = null;
} catch (Exception e) {
//e.printStackTrace();
} finally {
try {
if (null != os){
os.close();
os = null;
}
} catch (Exception e) {
//e.printStackTrace();
}
}
}
}3，使用方式，
xxxClass.addWaterMark("c:\path\srcImage.jpg",
,"c:\path\targetImage.gif"
,"c:\path\iconImage.png"
,"bottomright"
,new Float(0.8)
,0
,0);4，写在最后，
这个功能很多地方可以用到，具有公共方法属性，所以记录下来，日后使用，实际测试可用，可能有些简陋之处，欢迎大家提出指正或改进；当然还有其它的实现方式，如果你知道或有更好的实现方式，不妨回复或留下点滴.....