java图片动态添加水印（利用Graphics2D）

大家可能都对水印有了解，但是一般的水印都是事先生成的图片，比如

右下角会有一个水印logo，用来标明图片的出处。

但是如果有一个需求是，需要对某个网站的信息进行加密，对于每个信息都需要针对浏览者进行动态水印的添加，也就是浏览的时候才生成，如下图：

这时，我们就需要借用java中的2D画笔，来进行这个过程，代码如下：

public class WordIcon {private static String CSSCOLOR = "#bf8f79";private static float ALPHA = 0.4f;     public static ImgStreamBO createMark(WaterMarkBO waterMarkBO) {    BufferedImage bimage = buildGraph2d(waterMarkBO);    ImgStreamBO imgStreamBO = outputPic(bimage);    String imgName = waterMarkBO.getFileUrl().substring(waterMarkBO.getFileUrl().lastIndexOf("/")+1, waterMarkBO.getFileUrl().length());    imgStreamBO.setFileName(imgName+waterMarkBO.getUserId());    return imgStreamBO;    }    //构造2d画笔private static BufferedImage buildGraph2d(WaterMarkBO waterMarkBO){Color markContentColor = Color.gray;        URL url;try {url = new URL(waterMarkBO.getFileUrl());} catch (MalformedURLException e) {LoggerHelper.err(WordIcon.class, "pic url error");return null;}        ImageIcon imgIcon = new ImageIcon(url);        Image theImg = imgIcon.getImage();        //Image可以获得 输入图片的信息        int width = theImg.getWidth(null);        int height = theImg.getHeight(null);        //为画出图片的大小        BufferedImage bimage = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);        //2d 画笔        Graphics2D g = bimage.createGraphics();        g.setColor(markContentColor);        g.setBackground(Color.white);        //画出图片-----------------------------------        g.drawImage(theImg, 0, 0, null);        //--------对要显示的文字进行处理--------------        AttributedCharacterIterator iter = buildFont(waterMarkBO.getMarkContent(), waterMarkBO.getFontType(),        waterMarkBO.getFontSize());        Color color = Color.decode(CSSCOLOR);        g.setColor(color);        if (null != waterMarkBO.getDegree()) {            // 设置水印旋转            g.rotate(Math.toRadians(waterMarkBO.getDegree()),                    (double) bimage.getWidth() / 2, (double) bimage                    .getHeight() / 2);        }        g.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_ATOP,        ALPHA));        for(int i=0;i<9;i++){           for(int j = 0;j<6;j++){               g.drawString(iter, (int) (width - (width*j/4)), (int) (height - (height*i/8)));           }        }        //添加水印的文字和设置水印文字出现的内容 ----位置        g.dispose();//画笔结束return bimage;} //输出文件private static ImgStreamBO outputPic(BufferedImage bimage) {ByteArrayOutputStream out = null;ImgStreamBO imgStreamBO = new ImgStreamBO();try {            //输出 文件 到指定的路径            out = new ByteArrayOutputStream();            JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);            JPEGEncodeParam param = encoder.getDefaultJPEGEncodeParam(bimage);            param.setQuality(1, true);            encoder.encode(bimage, param);            byte[] buff = out.toByteArray();            imgStreamBO.setInput(new ByteArrayInputStream(buff));            imgStreamBO.setLength((long)buff.length);            return imgStreamBO;        } catch (Exception e) {        LoggerHelper.err(WordIcon.class, "get inputStream error");            return null;        }finally{        if(out!=null){        try {out.close();} catch (IOException e) {LoggerHelper.err(WordIcon.class, "close outputStream error");}        }        }}//形成字体属性private static AttributedCharacterIterator buildFont(String markContent,String fontType, int fontSize) {AttributedString ats = new AttributedString(markContent);        Font f = new Font(fontType, Font.PLAIN, fontSize);        ats.addAttribute(TextAttribute.FONT, f, 0, markContent.length());        AttributedCharacterIterator iter = ats.getIterator();return iter;}}

这个类传入的参数为一个封装好的BO，代码为：

public class WaterMarkBO {private String fileUrl;private String markContent;private String fontType;private int fontSize;private Integer degree;private Long userId;public WaterMarkBO(){}public WaterMarkBO(String fileUrl, String markContent, String fontType, int fontSize, Integer degree,Long userId){this.fileUrl = fileUrl;this.markContent = markContent;this.fontType = fontType;this.fontSize = fontSize;this.degree = degree;this.userId = userId;}……省略get,set方法}

这样的话，就可以动态的给图片添加水印。

如果是要给新闻添加水印的话，我们会选择将文章word转为pdf，然后再后台先将pdf转为图片，这样就可以保证前面的图片来源了。

附上将pdf转为图片的类：

public class PDFchangToImage {    public static List<String> changePdfToImg(String serverPath,String filePath,long articleId) {    List<String> picUrl = new ArrayList<String>();        try {        String path = serverPath            + File.separatorChar;            File file = new File(filePath);            RandomAccessFile raf = new RandomAccessFile(file, "r");            FileChannel channel = raf.getChannel();            MappedByteBuffer buf = channel.map(FileChannel.MapMode.READ_ONLY, 0, channel.size());            PDFFile pdffile = new PDFFile(buf);            for (int i = 1; i <= pdffile.getNumPages(); i++) {                PDFPage page = pdffile.getPage(i);                Rectangle rect = new Rectangle(0, 0, ((int) page.getBBox().getWidth()), ((int) page.getBBox().getHeight()));                int n = 2;/**图片清晰度（n>0且n<7）【pdf放大参数】*/                Image img = page.getImage(rect.width * n, rect.height * n, rect,  /**放大pdf到n倍，创建图片。*/null, /**null for the ImageObserver  */true, /** fill background with white  */true /** block until drawing is done  */);                BufferedImage tag = new BufferedImage(rect.width * n, rect.height * n, BufferedImage.TYPE_INT_RGB);                tag.getGraphics().drawImage(img, 0, 0, rect.width * n, rect.height * n, null);          /** File imgfile = new File("D:\\work\\mybook\\FilesNew\\img\\" + i + ".jpg");          if(imgfile.exists()){                if(imgfile.createNewFile())                {                    System.out.println("创建图片："+"D:\\work\\mybook\\FilesNew\\img\\" + i + ".jpg");                } else {                    System.out.println("创建图片失败！");                }            }  */                String singleFilePath = path + articleId + i +".jpg";                FileOutputStream out = new FileOutputStream(singleFilePath); /** 输出到文件流*/                picUrl.add(singleFilePath);                JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);                JPEGEncodeParam param2 = encoder.getDefaultJPEGEncodeParam(tag);                param2.setQuality(1f, true);/**1f~0.01f是提高生成的图片质量  */encoder.setJPEGEncodeParam(param2);                encoder.encode(tag);/** JPEG编码  */out.close();            }            channel.close();            raf.close();            unmap(buf);/**如果要在转图片之后删除pdf，就必须要这个关闭流和清空缓冲的方法*/        }catch (FileNotFoundException e) {            e.printStackTrace();        } catch (IOException e) {            e.printStackTrace();        }        return picUrl;    }    private static void unmap(final Object buffer) {        AccessController.doPrivileged(new PrivilegedAction() {            public Object run() {                try {                    Method getCleanerMethod = buffer.getClass().getMethod("cleaner", new Class[0]);                    getCleanerMethod.setAccessible(true);                    sun.misc.Cleaner cleaner = (sun.misc.Cleaner) getCleanerMethod.invoke(buffer, new Object[0]);                    cleaner.clean();                } catch (Exception e) {                    e.printStackTrace();                }                return null;            }        });    }}

如果觉得前面进行浏览时，速度跟不上，可以使用多线程和futuretask来帮你快速的完成图片处理。我试过多线程处理响应速度一般也就是1秒多一点点，基本处于可以接受的状态，而且如果觉得这样还不行，你可以考虑使用缓存文件系统，将生成的图片存储起来，下次如果发现有就不用再生成了。