Customizing JSPs with Dynamic Includes

The liferay-util:dynamic-include tag is placeholder into which you can inject content. Every JSP’s 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.

Blogs entries contain a good example of how dynamic includes work. For reference, you can download the example module.

Follow these steps:

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 an @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 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 JSP dynamically includes your content. Congratulations on injecting dynamic content into a JSP!