Servlet for serving static content

Question

I deploy a webapp on two different containers  Tomcat and Jetty   but their default servlets for serving the static content have a different way of handling the URL structure I want to use  details    I am therefore looking to include a small servlet in the webapp to serve its own static content  images  CSS  etc    The servlet should have the following properties    No external dependencies Simple and reliable Support for If-Modified-Since header  i e  custom getLastModified method   Optional  support for gzip encoding  etags       Is such a servlet available somewhere  The closest I can find is example 4-10 from the servlet book   Update  The URL structure I want to use - in case you are wondering - is simply        lt servlet-mapping gt               lt servlet-name gt main lt  servlet-name gt               lt url-pattern gt    lt  url-pattern gt       lt  servlet-mapping gt       lt servlet-mapping gt               lt servlet-name gt default lt  servlet-name gt               lt url-pattern gt  static   lt  url-pattern gt       lt  servlet-mapping gt    So all requests should be passed to the main servlet  unless they are for the static path  The problem is that Tomcat s default servlet does not take the ServletPath into account  so it looks for the static files in the main folder   while Jetty does  so it looks in the static folder

User · Answer

try this    lt servlet-mapping gt       lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   js lt  url-pattern gt       lt url-pattern gt   css lt  url-pattern gt       lt url-pattern gt   ico lt  url-pattern gt       lt url-pattern gt   png lt  url-pattern gt       lt url-pattern gt   jpg lt  url-pattern gt       lt url-pattern gt   htc lt  url-pattern gt       lt url-pattern gt   gif lt  url-pattern gt   lt  servlet-mapping gt        Edit  This is only valid for the servlet 2 5 spec and up

User · Answer

There is no need for completely custom implementation of the default servlet in this case  you can use this simple servlet to wrap request to the container s implementation    package com example   import java io     import javax servlet    import javax servlet http     public class DefaultWrapperServlet extends HttpServlet          public void doGet HttpServletRequest req  HttpServletResponse resp          throws ServletException  IOException               RequestDispatcher rd   getServletContext   getNamedDispatcher  default             HttpServletRequest wrapped   new HttpServletRequestWrapper req                public String getServletPath     return                           rd forward wrapped  resp

User · Answer

I ve had good results with FileServlet  as it supports pretty much all of HTTP  etags  chunking  etc

User · Answer

Use org mortbay jetty handler ContextHandler  You don t need additional components like StaticServlet   At the jetty home     cd contexts    cp javadoc xml static xml    vi static xml        lt Configure class  org mortbay jetty handler ContextHandler  gt   lt Set name  contextPath  gt  static lt  Set gt   lt Set name  resourceBase  gt  lt SystemProperty name  jetty home  default      gt  static  lt  Set gt   lt Set name  handler  gt     lt New class  org mortbay jetty handler ResourceHandler  gt       lt Set name  cacheControl  gt max-age 3600 public lt  Set gt     lt  New gt    lt  Set gt   lt  Configure gt    Set the value of contextPath with your URL prefix  and set the value of resourceBase as the file path of the static content   It worked for me

User · Answer

I had the same problem and I solved it by using the code of the  default servlet  from the Tomcat codebase  https   github com apache tomcat blob master java org apache catalina servlets DefaultServlet java The DefaultServlet is the servlet that serves the static resources  jpg html css gif etc  in Tomcat  This servlet is very efficient and has some the properties you defined above  I think that this source code  is a good way to start and remove the functionality or depedencies you don t need   References to the org apache naming resources package can be removed or replaced with java io File code  References to the org apache catalina util package are propably only utility methods classes that can be duplicated in your source code  References to the org apache catalina Globals class can be inlined or removed

User · Answer

Abstract template for a static resource servlet  Partly based on this blog from 2007  here s a modernized and highly reusable abstract template for a servlet which properly deals with caching  ETag  If-None-Match and If-Modified-Since  but no Gzip and Range support  just to keep it simple  Gzip could be done with a filter or via container configuration    public abstract class StaticResourceServlet extends HttpServlet        private static final long serialVersionUID   1L      private static final long ONE SECOND IN MILLIS   TimeUnit SECONDS toMillis 1       private static final String ETAG HEADER    W    s- s         private static final String CONTENT DISPOSITION HEADER    inline filename    1 s    filename  UTF-8   1 s        public static final long DEFAULT EXPIRE TIME IN MILLIS   TimeUnit DAYS toMillis 30       public static final int DEFAULT STREAM BUFFER SIZE   102400        Override     protected void doHead HttpServletRequest request  HttpServletResponse response  throws ServletException  IOException           doRequest request  response  true               Override     protected void doGet HttpServletRequest request  HttpServletResponse response  throws ServletException  IOException           doRequest request  response  false              private void doRequest HttpServletRequest request  HttpServletResponse response  boolean head  throws IOException           response reset            StaticResource resource           try               resource   getStaticResource request                     catch  IllegalArgumentException e                response sendError HttpServletResponse SC BAD REQUEST               return                     if  resource    null                response sendError HttpServletResponse SC NOT FOUND               return                     String fileName   URLEncoder encode resource getFileName    StandardCharsets UTF 8 name             boolean notModified   setCacheHeaders request  response  fileName  resource getLastModified              if  notModified                response sendError HttpServletResponse SC NOT MODIFIED               return                     setContentHeaders response  fileName  resource getContentLength              if  head                return                     writeContent response  resource                         Returns the static resource associated with the given HTTP servlet request  This returns  lt code gt null lt  code gt  when        the resource does actually not exist  The servlet will then return a HTTP 404 error          param request The involved HTTP servlet request          return The static resource associated with the given HTTP servlet request          throws IllegalArgumentException When the request is mangled in such way that it s not recognizable as a valid        static resource request  The servlet will then return a HTTP 400 error              protected abstract StaticResource getStaticResource HttpServletRequest request  throws IllegalArgumentException       private boolean setCacheHeaders HttpServletRequest request  HttpServletResponse response  String fileName  long lastModified            String eTag   String format ETAG HEADER  fileName  lastModified           response setHeader  ETag   eTag           response setDateHeader  Last-Modified   lastModified           response setDateHeader  Expires   System currentTimeMillis     DEFAULT EXPIRE TIME IN MILLIS           return notModified request  eTag  lastModified              private boolean notModified HttpServletRequest request  String eTag  long lastModified            String ifNoneMatch   request getHeader  If-None-Match             if  ifNoneMatch    null                String   matches   ifNoneMatch split    s    s                 Arrays sort matches               return  Arrays binarySearch matches  eTag   gt  -1    Arrays binarySearch matches        gt  -1                     else               long ifModifiedSince   request getDateHeader  If-Modified-Since                return  ifModifiedSince   ONE SECOND IN MILLIS  gt  lastModified      That second is because the header is in seconds  not millis                       private void setContentHeaders HttpServletResponse response  String fileName  long contentLength            response setHeader  Content-Type   getServletContext   getMimeType fileName            response setHeader  Content-Disposition   String format CONTENT DISPOSITION HEADER  fileName             if  contentLength    -1                response setHeader  Content-Length   String valueOf contentLength                         private void writeContent HttpServletResponse response  StaticResource resource  throws IOException           try               ReadableByteChannel inputChannel   Channels newChannel resource getInputStream                 WritableByteChannel outputChannel   Channels newChannel response getOutputStream                             ByteBuffer buffer   ByteBuffer allocateDirect DEFAULT STREAM BUFFER SIZE               long size   0               while  inputChannel read buffer     -1                    buffer flip                    size    outputChannel write buffer                   buffer clear                               if  resource getContentLength      -1  amp  amp   response isCommitted                      response setHeader  Content-Length   String valueOf size                                       Use it together with the below interface representing a static resource   interface StaticResource                   Returns the file name of the resource  This must be unique across all static resources  If any  the file        extension will be used to determine the content type being set  If the container doesn t recognize the        extension  then you can always register it as  lt code gt  amp lt mime-type amp gt  lt  code gt  in  lt code gt web xml lt  code gt           return The file name of the resource              public String getFileName                    Returns the last modified timestamp of the resource in milliseconds          return The last modified timestamp of the resource in milliseconds              public long getLastModified                    Returns the content length of the resource  This returns  lt code gt -1 lt  code gt  if the content length is unknown         In that case  the container will automatically switch to chunked encoding if the response is already        committed after streaming  The file download progress may be unknown          return The content length of the resource              public long getContentLength                    Returns the input stream with the content of the resource  This method will be called only once by the        servlet  and only when the resource actually needs to be streamed  so lazy loading is not necessary          return The input stream with the content of the resource          throws IOException When something fails at I O level              public InputStream getInputStream   throws IOException       All you need is just extending from the given abstract servlet and implementing the getStaticResource   method according the javadoc   Concrete example serving from file system   Here s a concrete example which serves it via an URL like  files foo ext from the local disk file system    WebServlet   files     public class FileSystemResourceServlet extends StaticResourceServlet        private File folder        Override     public void init   throws ServletException           folder   new File   path to the folder                Override     protected StaticResource getStaticResource HttpServletRequest request  throws IllegalArgumentException           String pathInfo   request getPathInfo             if  pathInfo    null    pathInfo isEmpty          equals pathInfo                 throw new IllegalArgumentException                       String name   URLDecoder decode pathInfo substring 1   StandardCharsets UTF 8 name             final File file   new File folder  Paths get name  getFileName   toString              return  file exists     null   new StaticResource                  Override             public long getLastModified                     return file lastModified                               Override             public InputStream getInputStream   throws IOException                   return new FileInputStream file                              Override             public String getFileName                     return file getName                               Override             public long getContentLength                     return file length                                        Concrete example serving from database   Here s a concrete example which serves it via an URL like  files foo ext from the database via an EJB service call which returns your entity having a byte   content property    WebServlet   files     public class YourEntityResourceServlet extends StaticResourceServlet         EJB     private YourEntityService yourEntityService        Override     protected StaticResource getStaticResource HttpServletRequest request  throws IllegalArgumentException           String pathInfo   request getPathInfo             if  pathInfo    null    pathInfo isEmpty          equals pathInfo                 throw new IllegalArgumentException                       String name   URLDecoder decode pathInfo substring 1   StandardCharsets UTF 8 name             final YourEntity yourEntity   yourEntityService getByName name            return  yourEntity    null    null   new StaticResource                  Override             public long getLastModified                     return yourEntity getLastModified                               Override             public InputStream getInputStream   throws IOException                   return new ByteArrayInputStream yourEntityService getContentById yourEntity getId                                 Override             public String getFileName                     return yourEntity getName                               Override             public long getContentLength                     return yourEntity getContentLength

User · Answer

Judging from the example information above  I think this entire article is based on a bugged behavior in Tomcat 6 0 29 and earlier   See https   issues apache org bugzilla show bug cgi id 50026   Upgrade to Tomcat 6 0 30 and the behavior between  Tomcat Jetty  should merge

User · Answer

I found great tutorial on the web about some workaround  It is simple and efficient  I used it in several projects with REST urls styles approach   http   www kuligowski pl java rest-style-urls-and-url-mapping-for-static-content-apache-tomcat 5

User · Answer

Checked for Tomcat 8 x  static resources work OK if root servlet map to     For servlet 3 x it could be done by  WebServlet

User · Answer

I did this by extending the tomcat DefaultServlet  src  and overriding the getRelativePath   method   package com example   import javax servlet ServletConfig  import javax servlet ServletException  import javax servlet http HttpServletRequest  import org apache catalina servlets DefaultServlet   public class StaticServlet extends DefaultServlet      protected String pathPrefix     static       public void init ServletConfig config  throws ServletException            super init config          if  config getInitParameter  pathPrefix      null                   pathPrefix   config getInitParameter  pathPrefix                     protected String getRelativePath HttpServletRequest req             return pathPrefix   super getRelativePath req                And here are my servlet mappings   lt servlet gt       lt servlet-name gt StaticServlet lt  servlet-name gt       lt servlet-class gt com example StaticServlet lt  servlet-class gt       lt init-param gt           lt param-name gt pathPrefix lt  param-name gt           lt param-value gt  static lt  param-value gt       lt  init-param gt          lt  servlet gt    lt servlet-mapping gt       lt servlet-name gt StaticServlet lt  servlet-name gt       lt url-pattern gt  static   lt  url-pattern gt   lt  servlet-mapping gt

User · Answer

I came up with a slightly different solution   It s a bit hack-ish  but here is the mapping    lt servlet-mapping gt          lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   html lt  url-pattern gt   lt  servlet-mapping gt   lt servlet-mapping gt       lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   jpg lt  url-pattern gt   lt  servlet-mapping gt   lt servlet-mapping gt    lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   png lt  url-pattern gt   lt  servlet-mapping gt   lt servlet-mapping gt       lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   css lt  url-pattern gt   lt  servlet-mapping gt   lt servlet-mapping gt       lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt   js lt  url-pattern gt   lt  servlet-mapping gt    lt servlet-mapping gt       lt servlet-name gt myAppServlet lt  servlet-name gt       lt url-pattern gt   lt  url-pattern gt   lt  servlet-mapping gt    This basically just maps all content files by extension to the default servlet  and everything else to  myAppServlet      It works in both Jetty and Tomcat

User · Answer

I ended up rolling my own StaticServlet  It supports If-Modified-Since  gzip encoding and it should be able to serve static files from war-files as well  It is not very difficult code  but it is not entirely trivial either   The code is available  StaticServlet java  Feel free to comment   Update  Khurram asks about the ServletUtils class which is referenced in StaticServlet  It is simply a class with auxiliary methods that I used for my project  The only method you need is coalesce  which is identical to the SQL function COALESCE   This is the code   public static  lt T gt  T coalesce T   ts        for T t  ts          if t    null              return t      return null

User · Answer

See StaticFile in JSOS  http   www servletsuite com servlets staticfile htm

User · Answer

To serve all requests from a Spring app as well as  favicon ico and the JSP files from  WEB-INF jsp   that Spring s AbstractUrlBasedView will request you can just remap the jsp servlet and default servlet      lt servlet gt       lt servlet-name gt springapp lt  servlet-name gt       lt servlet-class gt org springframework web servlet DispatcherServlet lt  servlet-class gt       lt load-on-startup gt 1 lt  load-on-startup gt     lt  servlet gt      lt servlet-mapping gt       lt servlet-name gt jsp lt  servlet-name gt       lt url-pattern gt  WEB-INF jsp   lt  url-pattern gt     lt  servlet-mapping gt      lt servlet-mapping gt       lt servlet-name gt default lt  servlet-name gt       lt url-pattern gt  favicon ico lt  url-pattern gt     lt  servlet-mapping gt      lt servlet-mapping gt       lt servlet-name gt springapp lt  servlet-name gt       lt url-pattern gt    lt  url-pattern gt     lt  servlet-mapping gt    We can t rely on the   jsp url-pattern on the standard mapping for the jsp servlet because the path pattern      is matched before any extension mapping is checked  Mapping the jsp servlet to a deeper folder means it s matched first  Matching   favicon ico  exactly happens before path pattern matching  Deeper path matches will work  or exact matches  but no extension matches can make it past the      path match  Mapping     to default servlet doesn t appear to work  You d think the exact     would beat the      path pattern on springapp   The above filter solution doesn t work for forwarded included JSP requests from the application  To make it work I had to apply the filter to springapp directly  at which point the url-pattern matching was useless as all requests that go to the application also go to its filters  So I added pattern matching to the filter and then learned about the  jsp  servlet and saw that it doesn t remove the path prefix like the default servlet does  That solved my problem  which was not exactly the same but common enough

[java] Servlet for serving static content

Examples related to java

Examples related to jsp

Examples related to servlets

Examples related to jakarta-ee