大家可能都對水印有了解，但是一般的水印都是事先生成的圖片，比如
右下角會有一個水印logo，用來標明圖片的出處。
但是如果有一個需求是，需要對某個網站的信息進行加密，對於每個信息都需要針對瀏覽者進行動態水印的添加，也就是瀏覽的時候才生成，如下圖：
這時，我們就需要借用java中的2D畫筆，來進行這個過程，代碼如下：
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;
}
//構造2d畫筆
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可以獲得 輸入圖片的信息
int width = theImg.getWidth(null);
int height = theImg.getHeight(null);
//爲畫出圖片的大小
BufferedImage bimage = new BufferedImage(width, height,BufferedImage.TYPE_INT_RGB);
//2d 畫筆
Graphics2D g = bimage.createGraphics();
g.setColor(markContentColor);
g.setBackground(Color.white);
//畫出圖片-----------------------------------
g.drawImage(theImg, 0, 0, null);
//--------對要顯示的文字進行處理--------------
AttributedCharacterIterator iter = buildFont(waterMarkBO.getMarkContent(), waterMarkBO.getFontType(),
waterMarkBO.getFontSize());
Color color = Color.decode(CSSCOLOR);
g.setColor(color);
if (null != waterMarkBO.getDegree()) {
// 設置水印旋轉
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)));
}
}
//添加水印的文字和設置水印文字出現的內容 ----位置
g.dispose();//畫筆結束
return bimage;
}
//輸出文件
private static ImgStreamBO outputPic(BufferedImage bimage) {
ByteArrayOutputStream out = null;
ImgStreamBO imgStreamBO = new ImgStreamBO();
try {
//輸出 文件 到指定的路徑
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");
}
}
}
}
//形成字體屬性
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;
}
}這個類傳入的參數爲一個封裝好的BO，代碼爲：
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
}如果是要給新聞添加水印的話，我們會選擇將文章word轉爲pdf，然後再後臺先將pdf轉爲圖片，這樣就可以保證前面的圖片來源了。
附上將pdf轉爲圖片的類：
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;/**圖片清晰度（n>0且n<7）【pdf放大參數】*/
Image img = page.getImage(rect.width * n, rect.height * n, rect, /**放大pdf到n倍，創建圖片。*/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("創建圖片："+"D:\\work\\mybook\\FilesNew\\img\\" + i + ".jpg"); } else { System.out.println("創建圖片失敗！"); } } */
String singleFilePath = path + articleId + i +".jpg";
FileOutputStream out = new FileOutputStream(singleFilePath); /** 輸出到文件流*/
picUrl.add(singleFilePath);
JPEGImageEncoder encoder = JPEGCodec.createJPEGEncoder(out);
JPEGEncodeParam param2 = encoder.getDefaultJPEGEncodeParam(tag);
param2.setQuality(1f, true);/**1f~0.01f是提高生成的圖片質量 */encoder.setJPEGEncodeParam(param2);
encoder.encode(tag);/** JPEG編碼 */out.close();
}
channel.close();
raf.close();
unmap(buf);/**如果要在轉圖片之後刪除pdf，就必須要這個關閉流和清空緩衝的方法*/
}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;
}
});
}
}如果覺得前面進行瀏覽時，速度跟不上，可以使用多線程和futuretask來幫你快速的完成圖片處理。我試過多線程處理響應速度一般也就是1秒多一點點，基本處於可以接受的狀態，而且如果覺得這樣還不行，你可以考慮使用緩存文件系統，將生成的圖片存儲起來，下次如果發現有就不用再生成了。