Customizing JSPs with Dynamic Includes

The liferay-util:dynamic-include tag is an extension point for inserting content (e.g., JavaScript code, HTML, and more). To do this, create a module that has content you want to insert, register that content with the dynamic include tag, and deploy your module.

Note: If the JSP you want to customize has no liferay-util:dynamic-include tags (or tags whose classes inherit from IncludeTag), you must use a different customization approach, such as portlet filters.

We’ll demonstrate how dynamic includes work using the Blogs entries. For reference, you can download the example module.

1. Find the liferay-util:dynamic-include tag where you want to insert content and note the tag’s key.

   The Blogs app’s view_entry.jsp has a dynamic include tag at the top and another at the very bottom.

   <%@ include file="/blogs/init.jsp" %>
   
   <liferay-util:dynamic-include key="com.liferay.blogs.web#/blogs/view_entry.jsp#pre" />
   
       ... JSP content is here
   
   <liferay-util:dynamic-include key="com.liferay.blogs.web#/blogs/view_entry.jsp#post" />
   

   Here are the Blogs view entry dynamic include keys:

   • key="com.liferay.blogs.web#/blogs/view_entry.jsp#pre"
   • key="com.liferay.blogs.web#/blogs/view_entry.jsp#post"

2. Create a module (e.g., blade create my-dynamic-include). The module will hold your dynamic include implementation.

3. Specify compile-only dependencies, like these Gradle dependencies, in your module build file:

   dependencies {
   	compileOnly group: "javax.portlet", name: "portlet-api", version: "2.0"
   	compileOnly group: "javax.servlet", name: "javax.servlet-api", version: "3.0.1"
   	compileOnly group: "com.liferay", name: "com.liferay.petra.string", version: "1.0.0"
   	compileOnly group: "com.liferay.portal", name: "com.liferay.portal.kernel", version: "2.0.0"
   	compileOnly group: "org.osgi", name: "osgi.cmpn", version: "6.0.0"
   }
   

4. Create an OSGi component class that implements the DynamicInclude interface.

   Here’s an example dynamic include implementation for Blogs:

   import java.io.IOException;
   import java.io.PrintWriter;
   
   import javax.servlet.http.HttpServletRequest;
   import javax.servlet.http.HttpServletResponse;
   
   import org.osgi.service.component.annotations.Component;
   
   import com.liferay.portal.kernel.servlet.taglib.DynamicInclude;
   
   @Component(
   	immediate = true,
   	service = DynamicInclude.class
   )
   public class BlogsDynamicInclude implements DynamicInclude {
   
   	@Override
   	public void include(
   			HttpServletRequest request, HttpServletResponse response,
   			String key)
   		throws IOException {
   
   		PrintWriter printWriter = response.getWriter();
   
   		printWriter.println(
   			"<h2>Added by Blogs Dynamic Include!</h2><br />");
   	}
   
   	@Override
   	public void register(DynamicIncludeRegistry dynamicIncludeRegistry) {
   		dynamicIncludeRegistry.register(
   			"com.liferay.blogs.web#/blogs/view_entry.jsp#pre");
   	}
   
   }
   

   Giving the class a @Component annotation that has the service attribute service = DynamicInclude.class makes the class a DynamicInclude service component.

   @Component(
       immediate = true,
       service = DynamicInclude.class
   )
   

   In the include method, add your content. The example include method writes a heading.

   @Override
   public void include(
           HttpServletRequest request, HttpServletResponse response,
           String key)
       throws IOException {
   
       PrintWriter printWriter = response.getWriter();
   
       printWriter.println(
       "<h2>Added by Blogs Dynamic Include!</h2><br />");
   }
   

   In the register method, specify the dynamic include tag you want to use. The example register method targets the dynamic include at the top of the Blogs view_entry.jsp.

   @Override
   public void register(DynamicIncludeRegistry dynamicIncludeRegistry) {
   	dynamicIncludeRegistry.register(
   		"com.liferay.blogs.web#/blogs/view_entry.jsp#pre");
   }
   

Once you’ve deployed your module, the overridden JSP dynamically includes your content. Congratulations on injecting dynamic content into a JSP!