1    package com.acme.filter; 
2     
3    import com.sun.image.codec.jpeg.JPEGImageEncoder; 
4     
5    import javax.servlet.FilterChain; 
6    import javax.servlet.ServletException; 
7    import javax.servlet.ServletRequest; 
8    import javax.servlet.ServletResponse; 
9    import javax.servlet.http.HttpServletResponse; 
10   import java.awt.*; 
11   import java.awt.image.BufferedImage; 
12   import java.io.ByteArrayOutputStream; 
13   import java.io.IOException; 
14   import java.io.OutputStream; 
15    
16   public class ImageFilter extends GenericFilter { 
17       public void doFilter(final ServletRequest request, final ServletResponse response, FilterChain chain) throws IOException, ServletException 
18       { 
19           String message = getFilterConfig().getInitParameter("message"); 
20           GenericResponseWrapper wrapper = new GenericResponseWrapper((HttpServletResponse) response); 
21           chain.doFilter(request, wrapper); 
22           OutputStream out = response.getOutputStream(); 
23           if (contentIsUncachedImage(wrapper) && message != null) 
24           { 
25               ByteArrayOutputStream imageStream = manipulateImage(message, wrapper.getData()); 
26               response.setContentLength(imageStream.size()); 
27               response.setContentType("image/jpeg"); 
28               out.write(imageStream.toByteArray()); 
29           } 
30           else 
31           { 
32               out.write(wrapper.getData()); 
33           } 
34           out.flush(); 
35           out.close(); 
36       }
 
37    
38       public ByteArrayOutputStream manipulateImage(String message, byte[] imageData) throws ServletException 
39       { 
40           ByteArrayOutputStream imageStream; 
41           Frame frame = null; 
42           Graphics graphics = null; 
43           try 
44           { 
45               frame = new Frame(); 
46               frame.addNotify(); 
47               MediaTracker mt = new MediaTracker(frame); // frame acts as an ImageObserver 
48               Image image = Toolkit.getDefaultToolkit().createImage(imageData); 
49               mt.addImage(image, 0); 
50               mt.waitForAll(); 
51               int w = image.getWidth(frame); 
52               int h = image.getHeight(frame); 
53               BufferedImage offscreen = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR); 
54               graphics = offscreen.getGraphics(); 
55               graphics.drawImage(image, 0, 0, frame); 
56               graphics.setFont(new Font("Arial", Font.BOLD | Font.ITALIC, 30)); 
57               graphics.setColor(Color.black); 
58               graphics.drawString(message, 10, 30); 
59               imageStream = new ByteArrayOutputStream(); 
60               JPEGImageEncoder encoder = com.sun.image.codec.jpeg.JPEGCodec.createJPEGEncoder(imageStream); 
61               encoder.encode(offscreen); 
62           } 
63           catch (InterruptedException e) 
64           { 
65               throw new ServletException(e.getMessage()); 
66           } catch (IOException e) 
67           { 
68               throw new ServletException(e.getMessage()); 
69           } 
70           finally 
71           { 
72               if (graphics != null) 
73               { 
74                   graphics.dispose(); 
75               } 
76               if (frame != null) 
77               { 
78                   frame.removeNotify(); 
79               } 
80           } 
81           return imageStream; 
82       }
 
83    
84       public boolean contentIsUncachedImage(GenericResponseWrapper wrapper) { 
85           if (wrapper.getContentType().startsWith("image/")) { 
86               if (wrapper.getData().length > 0) { 
87                   return true; 
88               } 
89           } 
90           return false; 
91       } 
92   } 
93