应用场景：企业在白纸上盖上印章，然后软件实现透明的电子印章，在后续业务流程中使用！
A4纸-----------------------------------------处理后-------------------------------------->电子印章
-------->
实现共分为3步
1. 图片上传后预览
上传图片
//POST file upload
//commons-fileupload-1.3.2.jar
//commons-io-2.5.jar
//commons-logging
//Thumbnails
String uploadsdir = request.getSession().getServletContext().getRealPath("/uploads") + File.separator;
String yyyyMM = (new SimpleDateFormat("yyyy-MM")).format(new Date());
File file = new File(uploadsdir + yyyyMM);
if (!file.exists()) {
file.mkdirs();
}
if (file.canWrite()) {
DiskFileItemFactory factory = new DiskFileItemFactory();
ServletContext servletContext = request.getSession().getServletContext();
File repository = (File)servletContext.getAttribute("javax.servlet.context.tempdir");
factory.setRepository(repository);
ServletFileUpload upload = new ServletFileUpload(factory);
upload.setFileSizeMax(1024*1024*10);//最大10M
try {
List items = upload.parseRequest(request);
Iterator iter = items.iterator();
if(iter.hasNext()) {
FileItem item = (FileItem)iter.next();
String fileName;
String contentType;
if (!item.isFormField()) {
fileName = item.getName();
contentType = item.getContentType();
if (contentType != null && "image/jpeg,image/gif,image/png,image/bmp,image/x-png,image/pjpeg".indexOf(contentType) == -1) {
response.sendRedirect("index.jsp?error=1");//不是图片类型
} else {
String last = fileName.substring(fileName.lastIndexOf("."), fileName.length());
String filename = UUID.randomUUID().toString().toLowerCase().replaceAll("-","") + last;
File savedFile = new File(file, filename);
item.write(savedFile);
//压缩 width 1000
Thumbnails.of(savedFile.getAbsolutePath()).width(1000)
.toFile(savedFile.getAbsoluteFile());
response.sendRedirect("corp.jsp?u=uploads/" + yyyyMM + "/" + filename);
}
}
}
} catch (Exception e) {
e.printStackTrace();
response.sendRedirect("index.jsp?error=5");//上传异常
}
} else {
response.sendRedirect("index.jsp?error=2");//文件夹不可写
}
} %>
2.预览后进行裁剪
图片裁剪
jQuery(function($){
var jcrop_api;
$('#target').Jcrop({
onChange: showCoords,
onSelect: showCoords,
onRelease: clearCoords
},function(){
jcrop_api = this;
});
$('#coords').on('change','input',function(e){
var x1 = $('#x1').val(),
x2 = $('#x2').val(),
y1 = $('#y1').val(),
y2 = $('#y2').val();
jcrop_api.setSelect([x1,y1,x2,y2]);
});
});
// Simple event handler, called from onChange and onSelect
// event handlers, as per the Jcrop invocation above
function showCoords(c)
{
$('#x1').val(c.x);
$('#y1').val(c.y);
$('#x2').val(c.x2);
$('#y2').val(c.y2);
$('#w').val(c.w);
$('#h').val(c.h);
};
function clearCoords()
{
$('#coords input').val('');
};
*{ margin:0px; padding:0px;}
" id="target" alt="上传图"/>
class="coords"
οnsubmit="return false;"
method="post"
action="corp.jsp">
" />
X1
Y1
X2
Y2
W
H
String u = request.getParameter("u");
String x1 = request.getParameter("x1");
String x2 = request.getParameter("x2");
String y1 = request.getParameter("y1");
String y2 = request.getParameter("y2");
String w = request.getParameter("w");
String h = request.getParameter("h");
if(u!=null&&w!=null&&h!=null&&x1!=null&&x2!=null) {
int int_x1 = Integer.parseInt(x1);
int int_y1 = Integer.parseInt(y1);
int int_w = Integer.parseInt(w);
int int_h = Integer.parseInt(h);
String uploadsdir = request.getSession().getServletContext().getRealPath("/");
String filepath = uploadsdir + u;
//crop to png
File inputfile = new File(filepath);
File outfile = new File(filepath.substring(0,filepath.lastIndexOf("."))+".png");
Thumbnails.of(inputfile).sourceRegion(int_x1, int_y1, int_w, int_h)
.size(int_w, int_h).outputFormat("png") .toFile(outfile);
//to apla
transApla(outfile);
//png file
u=u.substring(0,u.lastIndexOf("."))+".png";
response.sendRedirect("show.jsp?u=" + u);
}
} %>
//去掉图片背景
public void transApla(File file){
InputStream is=null;
try {
is = new FileInputStream(file);
// 如果是MultipartFile类型，那么自身也有转换成流的方法：is = file.getInputStream();
BufferedImage bi = ImageIO.read(is);
Image image = (Image) bi;
ImageIcon imageIcon = new ImageIcon(image);
BufferedImage bufferedImage = new BufferedImage(imageIcon.getIconWidth(), imageIcon.getIconHeight(),
BufferedImage.TYPE_4BYTE_ABGR);
Graphics2D g2D = (Graphics2D) bufferedImage.getGraphics();
g2D.drawImage(imageIcon.getImage(), 0, 0, imageIcon.getImageObserver());
int alpha = 0;
for (int j1 = bufferedImage.getMinY(); j1 < bufferedImage.getHeight(); j1++) {
for (int j2 = bufferedImage.getMinX(); j2 < bufferedImage.getWidth(); j2++) {
int rgb = bufferedImage.getRGB(j2, j1);
int R = (rgb & 0xff0000) >> 16;
int G = (rgb & 0xff00) >> 8;
int B = (rgb & 0xff);
if (((255 - R) < 30) && ((255 - G) < 30) && ((255 - B) < 30)) {
rgb = ((alpha + 1) << 24) | (rgb & 0x00ffffff);
}
bufferedImage.setRGB(j2, j1, rgb);
}
}
g2D.drawImage(bufferedImage, 0, 0, imageIcon.getImageObserver());
ImageIO.write(bufferedImage, "png", file);// 直接输出文件
} catch (Exception e) {
e.printStackTrace();
} finally {
if(is!=null){
try{
is.close();
}catch (Exception e){}
}
}
}
%>
3.裁剪图片进行png转换，然后白色背景变透明图
预览
" width="250" />
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