1   package com.atlassian.plugins.rest.module.filter;
2   
3   import com.sun.jersey.spi.container.ContainerRequest;
4   import com.sun.jersey.spi.container.ContainerRequestFilter;
5   import org.apache.commons.lang.StringUtils;
6   
7   import static javax.ws.rs.core.HttpHeaders.ACCEPT;
8   
9   import javax.ws.rs.core.MediaType;
10  
11  import static javax.ws.rs.core.MediaType.*;
12  
13  import javax.ws.rs.core.MultivaluedMap;
14  import javax.ws.rs.ext.Provider;
15  import java.util.HashSet;
16  import java.util.Set;
17  
18  /**
19   * <p>This is a filter to "fix" user agents with broken {@code Accept} headers.</p> <p>When a client accepts {@code
20   * text/html} we want it to be first in the header. This is because, it is likely that it is a browser and we then
21   * believe that HTML is the best view to render.</p> <p>This was introduced specifically to make Jersey MVC work with
22   * webkit based browsers which by default have their accept header set to {@code application/xml,application/xhtml+xml,text/html;q=0.9,text/plain;q=0.8,image/png,*\/*;q=0.5}</p>
23   * <p>The "fix" is to prepend {@code text/html} content type in the {@code Accept} header if it exists anywhere (else)
24   * in the header.</p>
25   * <p/>
26   * <p>When a client accepts {@link MediaType#WILDCARD} (IE) we want to prepend it with {@code text/html}.
27   */
28  @Provider
29  public class AcceptHeaderJerseyMvcFilter implements ContainerRequestFilter
30  {
31      final static Set<String> ACCEPTED_CONTENT_TYPES = new HashSet<String>()
32      {{
33              add(TEXT_PLAIN);
34              add(TEXT_HTML);
35              add(TEXT_HTML);
36              add(APPLICATION_JSON);
37              add(APPLICATION_XML);
38              add(APPLICATION_ATOM_XML);
39          }};
40  
41  
42      public ContainerRequest filter(final ContainerRequest request)
43      {
44          final MultivaluedMap<String, String> requestHeaders = request.getRequestHeaders();
45          final String acceptHeader = requestHeaders.getFirst(ACCEPT); // there should only be one Accept header
46  
47          String fixedHeader = addAppXmlWhenWildcardOnly(acceptHeader);
48          fixedHeader = moveTextHtmlToFront(fixedHeader);
49  
50          if (acceptHeader != null && !acceptHeader.equals(fixedHeader))
51              requestHeaders.putSingle(ACCEPT, fixedHeader);
52  
53          return request;
54      }
55  
56      private String addAppXmlWhenWildcardOnly(final String acceptHeader)
57      {
58          if (StringUtils.contains(acceptHeader, WILDCARD))
59          {
60              for (String contentType : ACCEPTED_CONTENT_TYPES)
61              {
62                  if (StringUtils.contains(acceptHeader, contentType))
63                  {
64                      return acceptHeader;
65                  }
66              }
67              return APPLICATION_XML + "," + acceptHeader;
68          }
69          return acceptHeader;
70      }
71  
72      private String moveTextHtmlToFront(final String acceptHeader)
73      {
74          if ((StringUtils.contains(acceptHeader, TEXT_HTML) || StringUtils.contains(acceptHeader, WILDCARD))
75                  && !StringUtils.startsWith(acceptHeader, TEXT_HTML))
76          {
77              return TEXT_HTML + "," + acceptHeader;
78          }
79          return acceptHeader;
80      }
81  }