这期内容当中小编将会给大家带来有关利用JAVA怎么给图片添加水印，文章内容丰富且以专业的角度为大家分析和叙述，阅读完这篇文章希望大家可以有所收获。
印的类型：
单文字水印
单图片水印
多文字水印
多图片水印
水印的开发流程：
创建图片缓存对象
创建Java绘图工具对象
使用绘图工具工具对象将原图绘制到缓存图片对象
使用绘图工具对象将水印（文字/图片）绘制到缓存图片
创建图像编码工具类
使用图像编码工具类，输出缓存图像到目标文件
单文字水印开发
所谓但文字水印，就是在一张图片上添加一条文字水印。其中我们主要的流程是通过ImageIO工具类解码对应的图片，然后创建BufferImage对象，通过BufferImage对象创建Graphics2D对象，再通过Graphics2D对象绘制原图到BufferImage对象。然后，我们还可以使用Graphics2D对象来设置水印的相关信息，如水印内容、字体大小、字体风格等。
这里需要说明的是我们需要计算水印文本的宽度，中文长度即文本宽度，英文长度为文本宽度的二分之一。具体可以参考我源码中的相关内容。
//计算水印文本长度
//1、中文长度即文本长度 2、英文长度为文本长度二分之一
public int getTextLength(String text){
//水印文字长度
int length = text.length();
for (int i = 0; i < text.length(); i++) {
String s =String.valueOf(text.charAt(i));
if (s.getBytes().length>1) {
length++;
}
}
length = length%2==0?length/2:length/2+1;
return length;
}//添加单条文字水印方法
public String textWaterMark(MultipartFile myFile,String imageFileName) {
InputStream is =null;
OutputStream os =null;
int X = 636;
int Y = 700;
try {
//使用ImageIO解码图片
Image image = ImageIO.read(myFile.getInputStream());
//计算原始图片宽度长度
int width = image.getWidth(null);
int height = image.getHeight(null);
//创建图片缓存对象
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//创建java绘图工具对象
Graphics2D graphics2d = bufferedImage.createGraphics();
//参数主要是，原图，坐标，宽高
graphics2d.drawImage(image, 0, 0, width, height, null);
graphics2d.setFont(new Font(FONT_NAME, FONT_STYLE, FONT_SIZE));
graphics2d.setColor(FONT_COLOR);
//使用绘图工具将水印绘制到图片上
//计算文字水印宽高值
int waterWidth = FONT_SIZE*getTextLength(MARK_TEXT);
int waterHeight = FONT_SIZE;
//计算水印与原图高宽差
int widthDiff = width-waterWidth;
int heightDiff = height-waterHeight;
//水印坐标设置
if (X > widthDiff) {
X = widthDiff;
}
if (Y > heightDiff) {
Y = heightDiff;
}
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
//纵坐标在下方，不增加字体高度会靠上
graphics2d.drawString(MARK_TEXT, X, Y+FONT_SIZE);
graphics2d.dispose();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
//创建图像编码工具类
JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(os);
//使用图像编码工具类，输出缓存图像到目标文件
en.encode(bufferedImage);
if(is!=null){
is.close();
}
if(os!=null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}单图片水印开发
单图片水印和上面单文字的代码流程大致一致，这里只讲解不同之处。
首先我们需要获得水印图片的路径，然后创建水印文件对象，同样通过ImageIO工具类解码水印图片，中间我们就不需要计算文本长宽了，因为单文字中的长宽即是我们水印图片的长宽。
//水印图片路径
//水印坐标设置
String logoPath = "/img/logo.png";
String realPath = request.getSession().getServletContext().getRealPath(logoPath);
File logo = new File(realPath);
Image imageLogo = ImageIO.read(logo);
int widthLogo = imageLogo.getWidth(null);
int heightLogo = imageLogo.getHeight(null);
int widthDiff = width-widthLogo;
int heightDiff = height-heightLogo;
//水印坐标设置
if (X > widthDiff) {
X = widthDiff;
}
if (Y > heightDiff) {
Y = heightDiff;
}
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.drawImage(imageLogo, X, Y, null);多文字水印开发
其实多文字水印开发和单文字也是类似的，主要的不同点是我们需要将BufferImage对象进行旋转。因为绘制水印并不支持旋转水印绘制，所以我们需要对原图进行旋转绘制，然后通过循环，我们就可以将一个文字水印多次绘制在原图上了。
//旋转原图，注意旋转角度为弧度制。后面两个参数为旋转的坐标中心
graphics2d.rotate(Math.toRadians(30), bufferedImage.getWidth()/2, bufferedImage.getHeight()/2);
int x = -width/2;
int y = -height/2;
while(x < width*1.5){
y = -height/2;
while(y < height*1.5){
graphics2d.drawString(MARK_TEXT, x, y);
y+=waterHeight+100;
}
x+=waterWidth+100;
}多图片水印开发
与上文相同，多图片水印需要先读取水印图片，然后对水印设置透明度，在对原图进行旋转，然后通过循环，我们就可以将一个图片水印多次绘制在原图上。
//水印图片路径
String logoPath = "/img/logo.png";
String realPath = request.getSession().getServletContext().getRealPath(logoPath);
File logo = new File(realPath);
Image imageLogo = ImageIO.read(logo);
int widthLogo = imageLogo.getWidth(null);
int heightLogo = imageLogo.getHeight(null);
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.rotate(Math.toRadians(30), bufferedImage.getWidth()/2, bufferedImage.getHeight()/2);
int x = -width/2;
int y = -height/2;
while(x < width*1.5){
y = -height/2;
while(y < height*1.5){
graphics2d.drawImage(imageLogo, x, y, null);
y+=heightLogo+100;
}
x+=widthLogo+100;
}业务类完整代码：
import java.awt.AlphaComposite;
import java.awt.Color;
import java.awt.Font;
import java.awt.Graphics2D;
import java.awt.Image;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.OutputStream;
import javax.imageio.ImageIO;
import javax.servlet.http.HttpServletRequest;
import org.springframework.stereotype.Service;
import org.springframework.web.multipart.MultipartFile;
import com.allan.service.WaterMarkService;
import com.sun.image.codec.jpeg.JPEGCodec;
import com.sun.image.codec.jpeg.JPEGImageEncoder;
@Service
public class WaterMarkServiceImpl implements WaterMarkService{
//定义上传的文件夹
private static final String UPLOAD_PATH = "E:/save";
//定义水印文字样式
private static final String MARK_TEXT = "小卖铺的老爷爷";
private static final String FONT_NAME = "微软雅黑";
private static final int FONT_STYLE = Font.BOLD;
private static final int FONT_SIZE = 60;
private static final Color FONT_COLOR = Color.black;
private static final float ALPHA = 0.3F;
//1、上传图片
public String uploadImage(MultipartFile myFile,String imageFileName) {
InputStream is =null;
OutputStream os =null;
try{
is = myFile.getInputStream();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
byte[] buffer =new byte[1024];
int len = 0;
while ((len=is.read(buffer))>0){
os.write(buffer);
}
}catch(Exception e){
e.printStackTrace();
}finally{
if(is!=null){
try {
is.close();
} catch (IOException e) {
e.printStackTrace();
}
}
if(os!=null){
try {
os.close();
} catch (IOException e2) {
e2.printStackTrace();
}
}
}
return "success";
}
//添加单条文字水印
public String textWaterMark(MultipartFile myFile,String imageFileName) {
InputStream is =null;
OutputStream os =null;
int X = 636;
int Y = 700;
try {
Image image = ImageIO.read(myFile.getInputStream());
//计算原始图片宽度长度
int width = image.getWidth(null);
int height = image.getHeight(null);
//创建图片缓存对象
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//创建java绘图工具对象
Graphics2D graphics2d = bufferedImage.createGraphics();
//参数主要是，原图，坐标，宽高
graphics2d.drawImage(image, 0, 0, width, height, null);
graphics2d.setFont(new Font(FONT_NAME, FONT_STYLE, FONT_SIZE));
graphics2d.setColor(FONT_COLOR);
//使用绘图工具将水印绘制到图片上
//计算文字水印宽高值
int waterWidth = FONT_SIZE*getTextLength(MARK_TEXT);
int waterHeight = FONT_SIZE;
//计算水印与原图高宽差
int widthDiff = width-waterWidth;
int heightDiff = height-waterHeight;
//水印坐标设置
if (X > widthDiff) {
X = widthDiff;
}
if (Y > heightDiff) {
Y = heightDiff;
}
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.drawString(MARK_TEXT, X, Y+FONT_SIZE);
graphics2d.dispose();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
//创建图像编码工具类
JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(os);
//使用图像编码工具类，输出缓存图像到目标文件
en.encode(bufferedImage);
if(is!=null){
is.close();
}
if(os!=null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}
//添加单图片水印
public String imageWaterMark(MultipartFile myFile,String imageFileName,HttpServletRequest request) {
InputStream is =null;
OutputStream os =null;
int X = 636;
int Y = 763;
try {
Image image = ImageIO.read(myFile.getInputStream());
//计算原始图片宽度长度
int width = image.getWidth(null);
int height = image.getHeight(null);
//创建图片缓存对象
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//创建java绘图工具对象
Graphics2D graphics2d = bufferedImage.createGraphics();
//参数主要是，原图，坐标，宽高
graphics2d.drawImage(image, 0, 0, width, height, null);
graphics2d.setFont(new Font(FONT_NAME, FONT_STYLE, FONT_SIZE));
graphics2d.setColor(FONT_COLOR);
//水印图片路径
String logoPath = "/img/logo.png";
String realPath = request.getSession().getServletContext().getRealPath(logoPath);
File logo = new File(realPath);
Image imageLogo = ImageIO.read(logo);
int widthLogo = imageLogo.getWidth(null);
int heightLogo = imageLogo.getHeight(null);
int widthDiff = width-widthLogo;
int heightDiff = height-heightLogo;
//水印坐标设置
if (X > widthDiff) {
X = widthDiff;
}
if (Y > heightDiff) {
Y = heightDiff;
}
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.drawImage(imageLogo, X, Y, null);
graphics2d.dispose();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
//创建图像编码工具类
JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(os);
//使用图像编码工具类，输出缓存图像到目标文件
en.encode(bufferedImage);
if(is!=null){
is.close();
}
if(os!=null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}
//添加多条文字水印
public String moreTextWaterMark(MultipartFile myFile,String imageFileName) {
InputStream is =null;
OutputStream os =null;
int X = 636;
int Y = 763;
try {
Image image = ImageIO.read(myFile.getInputStream());
//计算原始图片宽度长度
int width = image.getWidth(null);
int height = image.getHeight(null);
//创建图片缓存对象
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//创建java绘图工具对象
Graphics2D graphics2d = bufferedImage.createGraphics();
//参数主要是，原图，坐标，宽高
graphics2d.drawImage(image, 0, 0, width, height, null);
graphics2d.setFont(new Font(FONT_NAME, FONT_STYLE, FONT_SIZE));
graphics2d.setColor(FONT_COLOR);
//使用绘图工具将水印绘制到图片上
//计算文字水印宽高值
int waterWidth = FONT_SIZE*getTextLength(MARK_TEXT);
int waterHeight = FONT_SIZE;
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.rotate(Math.toRadians(30), bufferedImage.getWidth()/2, bufferedImage.getHeight()/2);
int x = -width/2;
int y = -height/2;
while(x < width*1.5){
y = -height/2;
while(y < height*1.5){
graphics2d.drawString(MARK_TEXT, x, y);
y+=waterHeight+100;
}
x+=waterWidth+100;
}
graphics2d.dispose();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
//创建图像编码工具类
JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(os);
//使用图像编码工具类，输出缓存图像到目标文件
en.encode(bufferedImage);
if(is!=null){
is.close();
}
if(os!=null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}
//多图片水印
public String moreImageWaterMark(MultipartFile myFile,String imageFileName,HttpServletRequest request) {
InputStream is =null;
OutputStream os =null;
int X = 636;
int Y = 763;
try {
Image image = ImageIO.read(myFile.getInputStream());
//计算原始图片宽度长度
int width = image.getWidth(null);
int height = image.getHeight(null);
//创建图片缓存对象
BufferedImage bufferedImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
//创建java绘图工具对象
Graphics2D graphics2d = bufferedImage.createGraphics();
//参数主要是，原图，坐标，宽高
graphics2d.drawImage(image, 0, 0, width, height, null);
graphics2d.setFont(new Font(FONT_NAME, FONT_STYLE, FONT_SIZE));
graphics2d.setColor(FONT_COLOR);
//水印图片路径
String logoPath = "/img/logo.png";
String realPath = request.getSession().getServletContext().getRealPath(logoPath);
File logo = new File(realPath);
Image imageLogo = ImageIO.read(logo);
int widthLogo = imageLogo.getWidth(null);
int heightLogo = imageLogo.getHeight(null);
//水印透明设置
graphics2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP, ALPHA));
graphics2d.rotate(Math.toRadians(30), bufferedImage.getWidth()/2, bufferedImage.getHeight()/2);
int x = -width/2;
int y = -height/2;
while(x < width*1.5){
y = -height/2;
while(y < height*1.5){
graphics2d.drawImage(imageLogo, x, y, null);
y+=heightLogo+100;
}
x+=widthLogo+100;
}
graphics2d.dispose();
os = new FileOutputStream(UPLOAD_PATH+"/"+imageFileName);
//创建图像编码工具类
JPEGImageEncoder en = JPEGCodec.createJPEGEncoder(os);
//使用图像编码工具类，输出缓存图像到目标文件
en.encode(bufferedImage);
if(is!=null){
is.close();
}
if(os!=null){
os.close();
}
} catch (IOException e) {
e.printStackTrace();
}
return "success";
}
//计算水印文本长度
//1、中文长度即文本长度 2、英文长度为文本长度二分之一
public int getTextLength(String text){
//水印文字长度
int length = text.length();
for (int i = 0; i < text.length(); i++) {
String s =String.valueOf(text.charAt(i));
if (s.getBytes().length>1) {
length++;
}
}
length = length%2==0?length/2:length/2+1;
return length;
}
}最后再说明下，本Demo是在上次的文件导入导出的框架基础上编写的，源码中有些其它Demo的代码，主要使用的类有WaterMarkController.java、WaterMarkService.java、WaterMarkServiceImpl.java，因为代码中我是硬编码到E:/save文件夹下的，如果要运行的话，还请先新建此文件夹，或者改为其他文件夹也行。
上述就是小编为大家分享的利用JAVA怎么给图片添加水印了，如果刚好有类似的疑惑，不妨参照上述分析进行理解。如果想知道更多相关知识，欢迎关注创新互联行业资讯频道。
