Jetty is a popular open-source web server and servlet container used for hosting Java web applications. One of its key features is its support for JavaServer Pages (JSP), a technology for creating dynamic web pages using Java. In this article, we will discuss how to configure Jetty's JSP support in embedded mode using Maven.
First, let's briefly explain what embedded mode means in the context of Jetty. Jetty can be run in two modes: standalone and embedded. Standalone mode is when Jetty is run as a standalone server, while embedded mode is when Jetty is run within another Java application. In this article, we will focus on running Jetty in embedded mode.
To get started, we need to create a Maven project and add the Jetty dependency to our project's pom.xml file. The Jetty dependency can be added by including the following code in the <dependencies> section of the pom.xml file:
```
<dependency>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-server</artifactId>
<version>9.4.12.v20180830</version>
</dependency>
```
Next, we need to configure the Jetty Maven plugin to run Jetty in embedded mode. We can do this by adding the following code to the <plugins> section of the pom.xml file:
```
<plugin>
<groupId>org.eclipse.jetty</groupId>
<artifactId>jetty-maven-plugin</artifactId>
<version>9.4.12.v20180830</version>
<configuration>
<webApp>
<contextPath>/</contextPath>
</webApp>
<jettyXml>src/test/resources/jetty.xml</jettyXml>
</configuration>
</plugin>
```
The <webApp> element specifies the context path for our application, while the <jettyXml> element points to a Jetty configuration file. In this case, we have specified a configuration file called jetty.xml which can be found in the src/test/resources directory of our project.
Next, we need to create the jetty.xml configuration file. This file will contain the necessary configuration for Jetty's JSP support. Here is a sample jetty.xml file:
```
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE Configure PUBLIC "-//Jetty//Configure//EN" "http://www.eclipse.org/jetty/configure_9_0.dtd">
<Configure class="org.eclipse.jetty.webapp.WebAppContext">
<Set name="contextPath">/</Set>
<Set name="war">
<SystemProperty name="user.dir" default="."/>/src/main/webapp
</Set>
<Call name="addServlet">
<Arg>jsp</Arg>
<Arg>org.apache.jasper.servlet.JspServlet</Arg>
<Arg>
<New class="org.eclipse.jetty.servlet.ServletHolder">
<Arg>
<New class="org.apache.jasper.servlet.JspServlet">
<Set name="logVerbosityLevel">DEBUG</Set>
<Set name="fork">false</Set>
<Set name="xpoweredBy">false</Set>
</New>
</Arg>
</New>
</Arg>
</Call>
</Configure>
```
In this file, we have specified the context path and the location of our web application's WAR file. We have also added a ServletHolder for Jetty's JspServlet, which is responsible for compiling and executing JSP files.
Now, we can run our application by executing the following command in the terminal:
```
mvn jetty:run
```
This will start Jetty in embedded mode and deploy our web application. We can then access our application by navigating to http://localhost:8080 in a web browser.
To test if Jetty's JSP support is working, we can create a simple JSP file in our web application's webapp directory. Here is an example index.jsp file:
```
<html>
<head>
<title>Jetty JSP Example</title>
</head>
<body>
<h1>Hello Jetty JSP!</h1>
</body>
</html>
```
When we navigate to http://localhost:8080/index.jsp, we should see the "Hello Jetty JSP!" message displayed.
In summary, we have discussed how to configure Jetty's JSP support in embedded mode using Maven. This allows us to run Jetty within our Java applications and take advantage of its powerful JSP capabilities. With this knowledge, you can now confidently use Jetty to host your Java web applications.
