@ -1295,8 +1295,8 @@ public void handle(@RequestBody String body, Writer writer) throws IOException {
@@ -1295,8 +1295,8 @@ public void handle(@RequestBody String body, Writer writer) throws IOException {
</section>
<section id= "mvc-ann-responsebody" >
<title > Mapping the response body with the @ResponseBody
annotation</title>
<title > Mapping the response body with the @ResponseBody
annotation</title>
<para > Similar to <interfacename > @RequestBody</interfacename> , there is
the <interfacename > @ResponseBody</interfacename> annotation. This
@ -1550,15 +1550,15 @@ public class MyFormController {
@@ -1550,15 +1550,15 @@ public class MyFormController {
<section id= "mvc-handlermapping" >
<title > Handler mappings</title>
<para > In previous versions of Spring MVC, users were required to define <interfacename > HandlerMapping</interfacename> s in
the web application context
to map incoming web requests to
appropriate handlers. With the introduction of Spring 2.5, the <classname > DispatcherServlet</classname> enables the
<classname > DefaultAnnotationHandlerMapping</classname> , which looks for
<interfacename > @RequestMapping</interfacename> annotations on <interfacename > @Controllers</interfacename> .
Typically, you do not need to override this default mapping, except when overriding the properties.
These properties are:
</para>
<para > In previous versions of Spring MVC, users were required to define
<interfacename > HandlerMapping</interfacename> s in the web application
context to map incoming web requests to appropriate handlers. With the
introduction of Spring 2.5, the <classname > DispatcherServlet</classname>
enables the <classname > DefaultAnnotationHandlerMapping</classname> , which
looks for <interfacename > @RequestMapping</interfacename> annotations on
<interfacename > @Controllers</interfacename> . Typically, you do not need to
override this default mapping, except when overriding the properties.
These properties are: </para>
<itemizedlist spacing= "compact" >
<listitem >
@ -1615,16 +1615,17 @@ public class MyFormController {
@@ -1615,16 +1615,17 @@ public class MyFormController {
subclasses of
<classname > org.springframework.web.servlet.handler.AbstractUrlHandlerMapping</classname> </emphasis> ).</para>
<para > The following example shows how to override the default mapping, and add an interceptor:</para>
<para > The following example shows how to override the default mapping, and
add an interceptor:</para>
<programlisting language= "xml" > <![CDATA[<beans>
<bean id= "handlerMapping" class= "org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping" >
<property name= "interceptors" >
<bean class= "example.MyInterceptor" />
</property>
</bean>
<programlisting language= "xml" > < beans>
< bean id="handlerMapping" class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
< property name="interceptors">
< bean class="example.MyInterceptor"/>
< /property>
< /bean>
<beans > ]]></programlisting>
< beans> </programlisting>
<section id= "mvc-handlermapping-interceptor" >
<title > Intercepting requests - the
@ -1841,10 +1842,11 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
@@ -1841,10 +1842,11 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
<row >
<entry > <classname > ContentNegotiatingViewResolver</classname> </entry>
<entry > An implementation of the <interfacename > ViewResolver</interfacename>
interface that that resolves a view based on the request file name or <literal > Accept</literal> header.
See <xref linkend= "mvc-multiple-representations" /> .
</entry>
<entry > An implementation of the
<interfacename > ViewResolver</interfacename> interface that that
resolves a view based on the request file name or
<literal > Accept</literal> header. See <xref
linkend="mvc-multiple-representations" />.</entry>
</row>
</tbody>
</tgroup>
@ -2068,139 +2070,138 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
@@ -2068,139 +2070,138 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
</section>
</section>
<section id= "mvc-multiple-representations" >
<title > <classname > ContentNegotiatingViewResolver</classname> </title>
<para > The <classname > ContentNegotiatingViewResolver</classname>
does not resolve views itself, but rather delegates to other
view resolvers, selecting the view that resembles the representation
requested by the client.
There are two strategies for a client to inform the server of
the representation it is interested in receiving.</para>
<para > The first strategy is to use a distinct URI for each resource.
This is typically done by using a different file extension in the URI.
For example the URI<literal >
http://www.example.com/users/fred.pdf</literal> requests a PDF
representation of the user fred while
<literal > http://www.example.com/users/fred.xml</literal> requests an XML
representation.</para>
<para > The second strategy is for the client to use the same URI to
locate the resource but set the <literal > Accept</literal> HTTP request
header to list the <ulink
url="http://en.wikipedia.org/wiki/Internet_media_type">media
types</ulink> that it understands. For example, a HTTP request for
<literal > http://www.example.com/users/fred</literal> with an
<literal > Accept</literal> header set to <literal > application/pdf
</literal> requests a PDF representation of the user fred while
<literal > http://www.example.com/users/fred</literal> with an
<literal > Accept</literal> header set to <literal > text/xml</literal>
requests an XML representation. This strategy is known as <ulink
url="http://en.wikipedia.org/wiki/Content_negotiation">content
negotiation</ulink> .</para>
<note >
<para > One issue with the Accept header is that is impossible to change
it in a web browser, in HTML. For instance, in Firefox, it's fixed
to</para>
<programlisting > Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
<section id= "mvc-multiple-representations" >
<title > <classname > ContentNegotiatingViewResolver</classname> </title>
<para > The <classname > ContentNegotiatingViewResolver</classname> does not
resolve views itself, but rather delegates to other view resolvers,
selecting the view that resembles the representation requested by the
client. There are two strategies for a client to inform the server of
the representation it is interested in receiving.</para>
<para > The first strategy is to use a distinct URI for each resource.
This is typically done by using a different file extension in the URI.
For example the URI<literal >
http://www.example.com/users/fred.pdf</literal> requests a PDF
representation of the user fred while
<literal > http://www.example.com/users/fred.xml</literal> requests an XML
representation.</para>
<para > The second strategy is for the client to use the same URI to
locate the resource but set the <literal > Accept</literal> HTTP request
header to list the <ulink
url="http://en.wikipedia.org/wiki/Internet_media_type">media
types</ulink> that it understands. For example, a HTTP request for
<literal > http://www.example.com/users/fred</literal> with an
<literal > Accept</literal> header set to <literal > application/pdf
</literal> requests a PDF representation of the user fred while
<literal > http://www.example.com/users/fred</literal> with an
<literal > Accept</literal> header set to <literal > text/xml</literal>
requests an XML representation. This strategy is known as <ulink
url="http://en.wikipedia.org/wiki/Content_negotiation">content
negotiation</ulink> .</para>
<note >
<para > One issue with the Accept header is that is impossible to change
it in a web browser, in HTML. For instance, in Firefox, it's fixed
to</para>
<programlisting > Accept: text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8
</programlisting>
<para > For this reason it is common to see the use of a distinct URI
for each representation.</para>
</note>
<para > To support multiple representations of a resource Spring provides
the <classname > ContentNegotiatingViewResolver</classname> to resolve a
view based on the file extension or <literal > Accept</literal> header of
the HTTP request. <classname > ContentNegotiatingViewResolver</classname>
does not perform the view resolution itself, but instead delegates to a
list of view resolvers set using the bean property
<literal > ViewResolvers</literal> .</para>
<para > The <classname > ContentNegotiatingViewResolver</classname> selects
an appropriate <classname > View</classname> to handle the request by
comparing the request media type(s) with the media type (a.k.a.
<literal > Content-Type</literal> ) supported by the
<classname > View</classname> associated with each of its
<classname > ViewResolvers</classname> . The first
<classname > View</classname> in the list that has a compatible
<literal > Content-Type</literal> is used to return the representation to
the client. The <literal > Accept</literal> header may include wild cards,
for example 'text/*', in which case a <classname > View</classname> whose
Context-Type was 'text/xml' is a compatible match.</para>
<para > To support the resolution of a view based on a file extension,
<classname > ContentNegotiatingViewResolver</classname> 's bean property
<literal > MediaTypes</literal> is used to specify a mapping of file
extensions to media types. For more information on the algorithm to
determine the request media type, refer to the API documentation for
<classname > ContentNegotiatingViewResolver</classname> ..</para>
<para > Here is an example configuration of a
<classname > ContentNegotiatingViewResolver</classname> </para>
<programlisting language= "xml" > <![CDATA[< bean class="org.springframework.web.servlet.view.ContentNegotiatingViewResolver">
<property name= "mediaTypes" >
<map >
<entry key= "atom" value= "application/atom+xml" />
<entry key= "html" value= "text/html" />
</map>
</property>
<property name= "viewResolvers" >
<list >
<bean class= "org.springframework.web.servlet.view.BeanNameViewResolver" />
<bean class= "org.springframework.web.servlet.view.InternalResourceViewResolver" >
<property name= "prefix" value= "/WEB-INF/jsp/" />
<property name= "suffix" value= ".jsp" />
</bean>
</list>
</property>
</bean>
<bean id= "content" class= "com.springsource.samples.rest.SampleContentAtomView" /> ]]></programlisting>
<para > The <classname > InternalResourceViewResolver</classname> handles
the translation of view names and JSP pages while the
<classname > BeanNameViewResolver</classname> returns a view based on the
name of a bean. (See "<link
linkend="mvc-viewresolver-resolver">Resolving views - the ViewResolver
interface</link> " for more details on how Spring looks up and
instantiates a view.) In this example, the <literal > content</literal>
bean is a class that inherits from
<classname > AbstractAtomFeedView</classname> which returns an Atom RSS
feed. For more information on creating an Atom Feed representation see
the section 'Atom Views'.</para>
<para > In this configuration, if a request is made with a .html extension
the view resolver will look for a view that matches the text/html media
type. The <classname > InternalResourceViewResolver</classname> provides
the matching view for text/html. If the request is made with the file
extension .atom, the view resolver will look for a view that matches the
application/atom+xml media type. This view is provided by the
<classname > BeanNameViewResolver</classname> that maps to the
<classname > SampleContentAtomView</classname> if the view name returned
is 'content'. Alternatively, client requests could be made without a
file extension and setting the Accept header to the preferred media-type
and the same resolution of request to views would occur.</para>
<note >
<para > If <classname > ContentNegotiatingViewResolver</classname> 's list
of ViewResolvers is not configured explicitly, then it will
automatically use any ViewResolvers defined in the application
context.</para>
</note>
<para > The corresponding controller code that returns an Atom RSS feed
for a URI of the form <literal > http://localhost/content.atom</literal>
or <literal > http://localhost/content</literal> with an
<literal > Accept</literal> header of application/atom+xml is shown
below</para>
<programlisting language= "java" > @Controller
<para > For this reason it is common to see the use of a distinct URI
for each representation.</para>
</note>
<para > To support multiple representations of a resource Spring provides
the <classname > ContentNegotiatingViewResolver</classname> to resolve a
view based on the file extension or <literal > Accept</literal> header of
the HTTP request. <classname > ContentNegotiatingViewResolver</classname>
does not perform the view resolution itself, but instead delegates to a
list of view resolvers set using the bean property
<literal > ViewResolvers</literal> .</para>
<para > The <classname > ContentNegotiatingViewResolver</classname> selects
an appropriate <classname > View</classname> to handle the request by
comparing the request media type(s) with the media type (a.k.a.
<literal > Content-Type</literal> ) supported by the
<classname > View</classname> associated with each of its
<classname > ViewResolvers</classname> . The first
<classname > View</classname> in the list that has a compatible
<literal > Content-Type</literal> is used to return the representation to
the client. The <literal > Accept</literal> header may include wild cards,
for example 'text/*', in which case a <classname > View</classname> whose
Context-Type was 'text/xml' is a compatible match.</para>
<para > To support the resolution of a view based on a file extension,
<classname > ContentNegotiatingViewResolver</classname> 's bean property
<literal > MediaTypes</literal> is used to specify a mapping of file
extensions to media types. For more information on the algorithm to
determine the request media type, refer to the API documentation for
<classname > ContentNegotiatingViewResolver</classname> ..</para>
<para > Here is an example configuration of a
<classname > ContentNegotiatingViewResolver</classname> </para>
<programlisting language= "xml" > < >
< property name="mediaTypes">
< map>
< entry key="atom" value="application/atom+xml"/>
< entry key="html" value="text/html"/>
< /map>
< /property>
< property name="viewResolvers">
< list>
< bean class="org.springframework.web.servlet.view.BeanNameViewResolver"/>
< bean class="org.springframework.web.servlet.view.InternalResourceViewResolver">
< property name="prefix" value="/WEB-INF/jsp/"/>
< property name="suffix" value=".jsp"/>
< /bean>
< /list>
< /property>
< /bean>
< bean id="content" class="com.springsource.samples.rest.SampleContentAtomView"/> </programlisting>
<para > The <classname > InternalResourceViewResolver</classname> handles
the translation of view names and JSP pages while the
<classname > BeanNameViewResolver</classname> returns a view based on the
name of a bean. (See "<link
linkend="mvc-viewresolver-resolver">Resolving views - the ViewResolver
interface</link> " for more details on how Spring looks up and
instantiates a view.) In this example, the <literal > content</literal>
bean is a class that inherits from
<classname > AbstractAtomFeedView</classname> which returns an Atom RSS
feed. For more information on creating an Atom Feed representation see
the section 'Atom Views'.</para>
<para > In this configuration, if a request is made with a .html extension
the view resolver will look for a view that matches the text/html media
type. The <classname > InternalResourceViewResolver</classname> provides
the matching view for text/html. If the request is made with the file
extension .atom, the view resolver will look for a view that matches the
application/atom+xml media type. This view is provided by the
<classname > BeanNameViewResolver</classname> that maps to the
<classname > SampleContentAtomView</classname> if the view name returned
is 'content'. Alternatively, client requests could be made without a
file extension and setting the Accept header to the preferred media-type
and the same resolution of request to views would occur.</para>
<note >
<para > If <classname > ContentNegotiatingViewResolver</classname> 's list
of ViewResolvers is not configured explicitly, then it will
automatically use any ViewResolvers defined in the application
context.</para>
</note>
<para > The corresponding controller code that returns an Atom RSS feed
for a URI of the form <literal > http://localhost/content.atom</literal>
or <literal > http://localhost/content</literal> with an
<literal > Accept</literal> header of application/atom+xml is shown
below</para>
<programlisting language= "java" > @Controller
public class ContentController {
private List< SampleContent> contentList = new ArrayList< SampleContent> ();
@ -2214,9 +2215,7 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
@@ -2214,9 +2215,7 @@ public class TimeBasedAccessInterceptor extends HandlerInterceptorAdapter {
}
}</programlisting>
</section>
</section>
</section>
<section id= "mvc-localeresolver" >
@ -2813,9 +2812,11 @@ public class FileUploadBean {
@@ -2813,9 +2812,11 @@ public class FileUploadBean {
<section id= "mvc-ann-exceptionhandler" >
<title > <interfacename > @ExceptionResolver</interfacename> </title>
<para > As an alternative to implementing the <interfacename > HandlerExceptionResolver</interfacename> , you
can use the <interfacename > @ExceptionHandler</interfacename> . The <classname > @ExceptionHandler</classname> method annotation is
used within a controller to specify which method will be invoked when an
<para > As an alternative to implementing the
<interfacename > HandlerExceptionResolver</interfacename> , you can use the
<interfacename > @ExceptionHandler</interfacename> . The
<classname > @ExceptionHandler</classname> method annotation is used
within a controller to specify which method will be invoked when an
exception of a specific type is thrown during the execution of
controller methods. For example</para>
@ -2851,7 +2852,6 @@ public class SimpleController {
@@ -2851,7 +2852,6 @@ public class SimpleController {
<classname > ModelAndView</classname> object. Please refer to the API
documentation for more details.</para>
</section>
</section>
<section id= "mvc-coc" >
@ -3189,6 +3189,49 @@ public class SimpleController {
@@ -3189,6 +3189,49 @@ public class SimpleController {
</section>
</section>
<section id= "mvc-etag" >
<title > ETag support</title>
<para > An <ulink url= "http://en.wikipedia.org/wiki/HTTP_ETag" > ETag</ulink>
(entity tag) is an HTTP response header returned by an HTTP/1.1 compliant
web server used to determine change in content at a given URL. It can be
considered to be the more sophisticated successor to the
<literal > Last-Modified</literal> header. When a server returns a
representation with an ETag header, the client can use this header in
subsequent GETs, in an <literal > If-None-Match</literal> header. If the
content has not changed, the server will return <literal > 304: Not
Modified</literal> .</para>
<para > Support for ETags is provided by the servlet filter
<classname > ShallowEtagHeaderFilter</classname> . Since it is a plain
Servlet Filter, and thus can be used in combination with any web
framework. The <classname > ShallowEtagHeaderFilter</classname> filter
creates so-called shallow ETags (as opposed to deep ETags, more about that
later). The way it works is quite simple: the filter simply caches the
content of the rendered JSP (or other content), generates an MD5 hash over
that, and returns that as an ETag header in the response. The next time a
client sends a request for the same resource, it uses that hash as the
<literal > If-None-Match</literal> value. The filter notices this, renders
the view again, and compares the two hashes. If they are equal, a
<literal > 304</literal> is returned. It is important to note that this
filter will not save processing power, as the view is still rendered. The
only thing it saves is bandwidth, as the rendered response is not sent
back over the wire.</para>
<para > You configure the <classname > ShallowEtagHeaderFilter</classname> in
<filename > web.xml</filename> :</para>
<programlisting language= "xml" > < filter>
< filter-name> etagFilter< /filter-name>
< filter-class> org.springframework.web.filter.ShallowEtagHeaderFilter< /filter-class>
< /filter>
< filter-mapping>
< filter-name> etagFilter< /filter-name>
< servlet-name> petclinic< /servlet-name>
< /filter-mapping> </programlisting>
</section>
<section id= "mvc-resources" >
<title > Further Resources</title>
Arjen Poutsma
16 years ago