spring how to pass values from one page to controller? - model-view-controller

Question

I am developing a spring mvc application . I just want to do the following ,
When user clicks on a link , I just want to pass some values from that page to the target Controller of that link.
Is AbstractCommandController will be useful for this ?
Is there any way other than using session attributes ?

Answer 1

You can do it in one of the following ways:
1) Submit Form.
2) Send it as parameters in your URL.
3) Create cusom flash scope for your application:
You can read more about it here:http://goo.gl/nQaQh
In spring MVC there is no Flash Bean scope so you can do it as Interceptor:
Here is the simple code how to use
public class FlashScopeInterceptor implements HandlerInterceptor {
public static final String DEFAULT_ATTRIBUTE_NAME = "flashScope";
public static final String DEFAULT_SESSION_ATTRIBUTE_NAME = FlashScopeInterceptor.class.getName();
public static final int DEFAULT_RETENTION_COUNT = 2;
private String sessionAttributeName = DEFAULT_SESSION_ATTRIBUTE_NAME;
private String attributeName = DEFAULT_ATTRIBUTE_NAME;
private int retentionCount = DEFAULT_RETENTION_COUNT;
/**
* Unbinds current flashScope from session. Rolls request's flashScope to
* the next scope. Binds request's flashScope, if not empty, to the session.
*
*/
#Override
public void afterCompletion(HttpServletRequest request, HttpServletResponse response, Object handler, Exception ex)
throws Exception {
if (request.getSession( false ) != null)
{
request.getSession().removeAttribute( this.sessionAttributeName );
}
Object requestAttribute = request.getAttribute( this.attributeName );
if (requestAttribute instanceof MultiScopeModelMap)
{
MultiScopeModelMap attributes = (MultiScopeModelMap) requestAttribute;
if (!attributes.isEmpty())
{
attributes.next();
if (!attributes.isEmpty())
{
request.getSession( true ).setAttribute( this.sessionAttributeName, attributes );
}
}
}
}
/**
* merge modelAndView.model['flashScope'] to current flashScope
*/
#Override
public void postHandle( HttpServletRequest request, HttpServletResponse response, Object handler,
ModelAndView modelAndView) throws Exception {
if (modelAndView != null)
{
Map<String, Object> modelFlashScopeMap = null;
for (Iterator<Entry<String, Object>> iterator = ((Map<String, Object>) modelAndView.getModel()).entrySet()
.iterator(); iterator.hasNext();)
{
Entry<String, Object> entry = iterator.next();
if (this.attributeName.equals( entry.getKey() ) && entry.getValue() instanceof Map)
{
if (modelFlashScopeMap == null)
{
modelFlashScopeMap = (Map) entry.getValue();
}
else
{
modelFlashScopeMap.putAll( (Map) entry.getValue() );
}
iterator.remove();
}
else if (entry.getKey().startsWith( this.attributeName + "." ))
{
String key = entry.getKey().substring( this.attributeName.length() + 1 );
if (modelFlashScopeMap == null)
{
modelFlashScopeMap = new HashMap<String, Object>();
}
modelFlashScopeMap.put( key, entry.getValue() );
iterator.remove();
}
}
if (modelFlashScopeMap != null)
{
MultiScopeModelMap flashScopeMap;
if (request.getAttribute( this.attributeName ) instanceof MultiScopeModelMap)
{
flashScopeMap = (MultiScopeModelMap) request.getAttribute( this.attributeName );
}
else
{
flashScopeMap = new MultiScopeModelMap( this.retentionCount );
}
flashScopeMap.putAll( modelFlashScopeMap );
request.setAttribute( this.attributeName, flashScopeMap );
}
}
}
/**
* binds session flashScope to current session, if not empty. Otherwise cleans up empty
* flashScope
*/
#Override
public boolean preHandle(HttpServletRequest request, HttpServletResponse response, Object handler) throws Exception {
HttpSession session = request.getSession( false );
if (session != null)
{
Object sessionAttribute = session.getAttribute( this.sessionAttributeName );
if (sessionAttribute instanceof MultiScopeModelMap)
{
MultiScopeModelMap flashScope = (MultiScopeModelMap) sessionAttribute;
if (flashScope.isEmpty())
{
session.removeAttribute( this.sessionAttributeName );
}
else
{
request.setAttribute( this.attributeName, flashScope );
}
}
}
return true;
}
}
and then MultiScopeModelMap
public class MultiScopeModelMap extends CompositeMap implements Serializable, MapMutator
{
public MultiScopeModelMap(int num)
{
super();
setMutator( this );
for(int i = 0; i < num; ++i)
{
addComposited( new HashMap() );
}
}
/** Shadows composite map. */
private final LinkedList<Map> maps = new LinkedList<Map>();
#Override
public synchronized void addComposited( Map map ) throws IllegalArgumentException
{
super.addComposited( map );
this.maps.addLast( map );
}
#Override
public synchronized Map removeComposited( Map map )
{
Map removed = super.removeComposited( map );
this.maps.remove( map );
return removed;
}
/**
* Starts a new scope.
* All items added in the session before the previous session are removed.
* All items added in the previous scope are still retrievable and removable.
*/
public void next()
{
removeComposited( this.maps.getFirst() );
addComposited( new HashMap() );
}
public Object put( CompositeMap map, Map[] composited, Object key, Object value )
{
if(composited.length < 1)
{
throw new UnsupportedOperationException("No composites to add elements to");
}
Object result = map.get( key );
if(result != null)
{
map.remove( key );
}
composited[composited.length-1].put( key, value );
return result;
}
public void putAll( CompositeMap map, Map[] composited, Map mapToAdd )
{
for(Entry entry: (Set<Entry>)mapToAdd.entrySet())
{
put(map, composited, entry.getKey(), entry.getValue());
}
}
public void resolveCollision( CompositeMap composite, Map existing, Map added, Collection intersect )
{
existing.keySet().removeAll( intersect );
}
#Override
public String toString()
{
return new HashMap(this).toString();
}
}
Now configure it in xml:
<bean id="flashScopeInterceptor" class="com.vanilla.scopes.FlashScopeInterceptor" />
<bean id="handlerMapping" class="org.springframework.web.servlet.mvc.annotation.DefaultAnnotationHandlerMapping">
<property name="interceptors">
<list><ref bean="flashScopeInterceptor"/></list>
</property>
</bean>
Usage:
#RequestMapping(value="/login.do", method=RequestMethod.POST)
public ModelAndView login(#Valid User user){
ModelAndView mv = new ModelAndView("redirect:result.html");
if (authService.authenticate(user.getUserName(), user.getPassword()))
mv.addObject("flashScope.message", "Success");
//else
mv.addObject("flashScope.message", "Login Failed");
return mv;
}
#RequestMapping(value ="/result.html", method=RequestMethod.GET)
public ModelAndView result(){
ModelAndView mv = new ModelAndView("login/loginAction");
return mv;
}
In JSP the usage is very simple:
${flashScope.message}