LinkedHashMap as LRU cache. Also, I've found such code with a direct link as comment in Apache Roller source code.
LinkedHashMap can be used as LRU cache because it supports ordering it's elements not only by insert order, but also by access-order. Also there is protected method removeEldestEntry in the LinkedHashMap that runs in the put() and putAll() methods. If that method returns true, than least recently inserted/accessed element will be removed.
web.xml add the freemarker configuration.
<servlet>
<servlet-name>pages</servlet-name>
<servlet-class>org.springframework.web.servlet.DispatcherServlet</servlet-class>
</servlet>
<servlet-mapping>
<servlet-name>pages</servlet-name>
<url-pattern>*.page</url-pattern>
</servlet-mapping>
<servlet>
<servlet-name>freemarker</servlet-name>
<servlet-class>freemarker.ext.servlet.FreemarkerServlet</servlet-class>
<init-param>
<param-name>TemplatePath</param-name>
<param-value>/</param-value>
</init-param>
<init-param>
<param-name>NoCache</param-name>
<param-value>true</param-value>
</init-param>
<init-paramv
<param-name>ContentType</param-name>
<param-value>text/html</param-value>
</init-param>
....
<load-on-startup>1</load-on-startup>
</servlet>
<servlet-mapping>
<servlet-name>freemarker</servlet-name>
<url-pattern>*.ftl</url-pattern>
</servlet-mapping>
<!-- Tiles 2 configuration-->
<bean id="tilesConfigurer" class="org.springframework.web.servlet.view.tiles2.TilesConfigurer">
<property name="definitions">
<list>
<!-- the tiles configuration files are declared here -->
<value>/WEB-INF/defs/general.xml</value>
<value>/WEB-INF/defs/secure.xml</value>
</list>
</property>
</bean>
<bean id="tilesViewResolver" class="com.javaua.spring.integration.ext.ExtUrlBasedViewResolver">
<property name="viewClass" value="com.javaua.spring.integration.ext.ExtTilesView"/>
<property name="exposeSpringMacroModel" value="true"/>
</bean>
<bean id="viewResolver" class="org.springframework.web.servlet.view.freemarker.FreeMarkerViewResolver">
<property name="cache" value="true"/>
<property name="prefix" value=""/>
<property name="suffix" value=".ftl"/>
<!-- if you want to use the Spring FreeMarker macros, set this property to true -->
<property name="exposeSpringMacroHelpers" value="true"/>
</bean>
<!-- Controller that returns view = /layout/header -->
<bean name="/layout/header.page" class="com.javaua.HeaderController"/>
<definition name="home" extends="default">
<put-attribute name="title" value="Home Page"/>
<put-attribute name="body" value="/templates/home.ftl"/>
</definition>
<definition name="default" template="/templates/main.ftl">
<put-attribute name="header" value="/layout/header.page"/>
<put-attribute name="footer" value="/templates/layout/footer.ftl"/>
</definition>
<definition name="/layout/header" template="/templates/layout/header.ftl"/>
com.javaua.spring.integration.ext.ExtUrlBasedViewResolver class:
import org.springframework.core.Ordered;
import org.springframework.web.servlet.View;
import org.springframework.web.servlet.view.AbstractUrlBasedView;
import org.springframework.web.servlet.view.UrlBasedViewResolver;
public class ExtUrlBasedViewResolver extends UrlBasedViewResolver implements Ordered {
private boolean exposeSpringMacroModel = false;
public void setExposeSpringMacroModel(boolean exposeSpringMacroModel) {
this.exposeSpringMacroModel = exposeSpringMacroModel;
}
protected View loadView(String viewName, Locale locale) throws Exception {
AbstractUrlBasedView view = buildView(viewName);
View viewObj = (View) getApplicationContext().getAutowireCapableBeanFactory().initializeBean(view, viewName);
if (viewObj instanceof ExtTilesView) {
ExtTilesView tilesView = (ExtTilesView) viewObj;
tilesView.setExposeSpringMacroModel(exposeSpringMacroModel);
}
return viewObj;
}
com.javaua.spring.integration.ext.ExtTilesView class:
import org.springframework.web.servlet.view.tiles2.TilesView;
import org.springframework.web.servlet.view.AbstractTemplateView;
import org.springframework.web.servlet.support.RequestContext;
import javax.servlet.http.HttpServletResponse;
import javax.servlet.http.HttpServletRequest;
import javax.servlet.ServletException;
import java.util.Map;
public class ExtTilesView extends TilesView {
private boolean exposeSpringMacroModel = false;
public void setExposeSpringMacroModel(boolean exposeSpringMacroModel) {
this.exposeSpringMacroModel = exposeSpringMacroModel;
}
@SuppressWarnings("unchecked")
protected final void renderMergedOutputModel(Map model, HttpServletRequest request,
HttpServletResponse response) throws Exception {
if (exposeSpringMacroModel) {
if (model.containsKey(AbstractTemplateView.SPRING_MACRO_REQUEST_CONTEXT_ATTRIBUTE)) {
throw new ServletException(
"Cannot expose bind macro helper '" +
AbstractTemplateView.SPRING_MACRO_REQUEST_CONTEXT_ATTRIBUTE +
"' because of an existing model object of the same name");
}
model.put(AbstractTemplateView.SPRING_MACRO_REQUEST_CONTEXT_ATTRIBUTE,
new RequestContext(request, getServletContext(), model));
}
super.renderMergedOutputModel(model, request, response);
}
}
ExtTilesView exposes Spring macro model which is required when using standard macros used to support work with Freemarker and Velocity typelate frameworks. And the class ExtUrlBasedViewResolver helps us to prevent view-not-found-error. Because, standard UrlBasedViewResolver is used for getting tiles view, it will throw an error when view with specified name is not found. In my case, I have two view resolvers and each will throw an error if view can't be found. FreeMarkerViewResolver will request for the file, while tiles requests just for XML definition. That's why I've ran the tiles view resolver as first one.Мабуть, нікому не секрет, що GC є дуже важливою річчю в JVM, і що вона займається звільненням памяті, що вже не використовуються. Також багатьом відомо, що є кілька різних політик виконання очистки пам'яті. Конфігурація не виглядає надто складною, є всього кілька можливих варіантів вибору політики GC:
-Xms256m
-Xmx512m
-XX:MaxPermSize=120m
-XX:+UseConcMarkSweepGC
-ea
-Dawt.useSystemAAFontSettings=lcd
-Xms512m
-Xmx512m
-XX:MaxPermSize=120m
-XX:+UseConcMarkSweepGC
-ea
-Dawt.useSystemAAFontSettings=lcd