What is the difference between jsp include page and include file

Question

Both tags include the content from one page in another   So what is the exact difference between these two tags

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There s a huge difference  As has been mentioned   lt    include is a static include   lt jsp include is a dynamic include  Think of it as a difference between a macro and a function call  if you are familiar with those terms   Another way of putting it  a static include is exactly the same thing as copy-pasting the exact content of the included file  the  code   at the location of the  lt    include statement  which is exactly what the JSP compiler will do   A dynamic include will make a request  using the request dispatcher  that will execute the indicated page and then include the output from the page in the output of the calling page  in place of the  lt jsp include statement   The big difference here is that with a dynamic include  the included page will execute in it s own pageContext  And since it s a request  you can send parameters to the page the same way you can send parameters along with any other request  A static include  on the other hand  is just a piece of code that will execute inside the context of the calling page  If you statically include the same file more than once  the code in that file will exist in multiple locations on the calling page so something like   lt   int i   0    gt    would generate a compiler error  since the same variable can t be declared more than once

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Java Revisited   Resource included by include directive is loaded during jsp translation time  while resource included by include action is loaded during request time  Any change on included resource will not be visible in case of include directive until jsp file compiles again  While in case of include action  any change in included resource will be visible in next request  Include directive is static import  while include action is dynamic import Include directive uses file attribute to specify resource to be included while include action use page attribute for same purpose

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In one reusable piece of code I use the directive  lt   include file  quot reuse html quot   gt  and in the second I use the standard action  lt jsp include page  quot reuse html quot    gt   Let the code in the reusable file be   lt html gt   lt head gt       lt title gt reusable lt  title gt       lt meta http-equiv  quot Content-Type quot  content  quot text html  charset UTF-8 quot  gt   lt  head gt   lt body gt       lt img src  quot candle gif quot  height  quot 100 quot  width  quot 50 quot   gt   lt br   gt       lt p gt  lt b gt As the candle burns so do I lt  b gt  lt  p gt   lt  body gt    After running both the JSP files you see the same output and think if there was any difference between the directive and the action tag  But if you look at the generated servlet of the two JSP files  you will see the difference  Here is what you will see when you use the directive  out write  quot  lt html gt  r n quot    out write  quot      lt head gt  r n quot    out write  quot          lt title gt reusable lt  title gt  r n quot    out write  quot          lt meta http-equiv   quot Content-Type  quot  content   quot text html  charset UTF-8  quot  gt  r n quot    out write  quot      lt  head gt  r n quot    out write  quot      lt body gt  r n quot    out write  quot          lt img src   quot candle gif  quot  height   quot 100  quot  width   quot 50  quot   gt   lt br   gt  r n quot    out write  quot          lt p gt  lt b gt As the candle burns so do I lt  b gt  lt  p gt  r n quot    out write  quot      lt  body gt  r n quot    out write  quot  lt  html gt  r n quot       And this is what you will see for the used standard action in the second JSP file   org apache jasper runtime JspRuntimeLibrary include request  response   quot reusable html quot   out  false    So now you know that the include directive inserts the source of reuse html at translation time  but the action tag inserts the response of reuse html at runtime  If you think about it  there is an extra performance hit with every action tag   lt jsp include gt    It means you can guarantee you will always have the latest content  but it increases performance cost

User · Answer

One is a static import   lt     include        the other is a dynamic one  jsp include   It will affect for example the path you gonna have to specify for your included file  A little research on Google will tell you more

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1  When to use include directive    To prevent duplication of same output logic across multiple jsp s of the web app  include mechanism is used ie  to promote the re-usability of presentation logic include directive is used      lt    include file  abc jsp    gt    when the above instruction is received by the jsp engine it retrieves the source code of the abc jsp and copy s the same inline in the current jsp  After copying translation is performed for the current page  Simply saying it is static instruction to jsp engine ie   whole source code of  abc jsp  is copied into the current page   2  When to use include action    include tag doesn t include the source code of the included page into the current page instead the output generated at run time by the included page is included into the current page response  include tag functionality is similar to that of include mechanism of request dispatcher of servlet programming   include tag is run-time instruction to jsp engine ie   rather copying whole code into current page a method call is made to  abc jsp  from current page

User · Answer

jGuru      The  lt   include file  abc jsp   gt  directive acts like C   include     pulling in the text of the included file and compiling it as if it   were part of the including file  The included file can be any type    including HTML or text        The  lt jsp include page  abc jsp  gt  tag compiles the file as a separate   JSP file  and embeds a call to it in the compiled JSP       Some JSP engines support the non-standard tags  lt  -- include   file  data inc -- gt   NCSA-  or  shtml-style  and  lt      vinclude  data inc    gt   JRun-style   but these are not defined in the   JSP spec and thus cannot be relied on       See also this question in the JSP FAQ

[java] What is the difference between <jsp:include page = ... > and <%@ include file = ... >?

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