Spring MVC

From Chunk Java Template Engine

Revision as of 07:44, 29 June 2015

Can I use Chunk Templates in my Spring MVC project?

Yes!

Chunk 2.6.4 adds some new plumbing that makes it easy to use with Spring MVC, as a drop-in replacement template engine for Freemarker or Velocity.

Is there a sample project that I can clone?

Why yes, just head here: Sample Spring MVC project on GitHub

You'll be up and running in no time.

How does it work?

Here's what you will need:

1. pom.xml dependencies:

  ...
  <dependencies>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-context</artifactId>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-aop</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-webmvc</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>org.springframework</groupId>
        <artifactId>spring-web</artifactId>
        <version>4.1.5.RELEASE</version>
    </dependency>
    <dependency>
        <groupId>jstl</groupId>
        <artifactId>jstl</artifactId>
        <version>1.2</version>
    </dependency>
    <dependency>
        <groupId>commons-logging</groupId>
        <artifactId>commons-logging</artifactId>
        <version>1.2</version>
    </dependency>
    <dependency>
        <groupId>com.x5dev</groupId>
        <artifactId>chunk-templates</artifactId>
        <version>2.6.4</version>
    </dependency>
  </dependencies>
  <dependencyManagement>
    <dependencies>
        <dependency>
            <groupId>org.springframework</groupId>
            <artifactId>spring-context</artifactId>
            <version>4.1.5.RELEASE</version>
        </dependency>
    </dependencies>
  </dependencyManagement>
  ...

2. WebContent/WEB-INF/web.xml

<?xml version="1.0" encoding="UTF-8"?>

<web-app version="2.4"
     xmlns="http://java.sun.com/xml/ns/j2ee"
     xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
     xsi:schemaLocation="http://java.sun.com/xml/ns/j2ee 
     http://java.sun.com/xml/ns/j2ee/web-app_2_4.xsd" >

    <display-name>Chunky Spring</display-name>

    <servlet>
        <servlet-name>dispatcher</servlet-name>
        <servlet-class>
            org.springframework.web.servlet.DispatcherServlet
        </servlet-class>
        <load-on-startup>1</load-on-startup>
    </servlet>

    <servlet-mapping>
        <servlet-name>dispatcher</servlet-name>
        <url-pattern>/</url-pattern>
    </servlet-mapping>

    <context-param>
        <param-name>contextConfigLocation</param-name>
        <param-value>/WEB-INF/dispatcher-servlet.xml</param-value>
    </context-param>

    <listener>
        <listener-class>
            org.springframework.web.context.ContextLoaderListener
        </listener-class>
    </listener>

</web-app>

3. WebContent/WEB-INF/dispatcher-servlet.xml - provide some Theme configuration and drop in a custom view class (source below) to viewResolver.

Make sure to change com.example.myapp to the package where your annotated controllers live.

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="http://www.springframework.org/schema/beans

http://www.springframework.org/schema/beans/spring-beans-4.0.xsd
http://www.springframework.org/schema/context 
http://www.springframework.org/schema/context/spring-context-4.0.xsd">

    <context:component-scan base-package="com.example.myapp" />

    <bean id="chunkTemplatesConfig" class="java.util.HashMap" scope="prototype">
        <constructor-arg>
            <map key-type="java.lang.String" value-type="java.lang.String">
                <entry key="default_extension" value="chtml" />
                <entry key="cache_minutes" value="0" />
                <entry key="layers" value="" />
                <entry key="theme_path" value="" />
                <entry key="hide_errors" value="FALSE" />
                <entry key="error_log" value="" />
                <entry key="encoding" value="UTF-8" />
                <entry key="locale" value="" />
                <entry key="filters" value="" />
            </map>
        </constructor-arg>
    </bean>

    <bean id="viewResolver" class="org.springframework.web.servlet.view.InternalResourceViewResolver">
        <property name="viewClass" value="com.x5.template.spring.ChunkTemplateView"/>
        <property name="prefix" value="/WEB-INF/themes/"/>
        <property name="suffix" value=".chtml"/>
        <property name="requestContextAttribute" value="rc"/>
    </bean>
</beans>

4. Include the custom view class in your project source (this may get packaged into a maven dependency at some point if there is demand/interest).

ChunkTemplateView.java

package com.x5.template.spring;

import org.springframework.web.servlet.support.RequestContext;
import org.springframework.web.servlet.view.InternalResourceView;
import org.springframework.beans.factory.NoSuchBeanDefinitionException;
import org.springframework.core.io.Resource;

import com.x5.template.Theme;
import com.x5.template.ThemeConfig;
import com.x5.template.Chunk;

import javax.servlet.http.HttpServletRequest;
import javax.servlet.http.HttpServletResponse;

import java.util.HashMap;
import java.util.Map;
import java.io.PrintWriter;

public class ChunkTemplateView extends InternalResourceView
{
    private static Theme theme = null;

    @Override
    protected void renderMergedOutputModel(
        Map<String, Object> model,
        HttpServletRequest request,
        HttpServletResponse response
    ) throws Exception
    {
        Resource templateFile = getApplicationContext().getResource(getUrl());

        String rcKey = getRequestContextAttribute();
        RequestContext rc = (RequestContext)model.get(rcKey);

        Theme theme = getTheme(templateFile.getFile().getParent());
        Chunk chunk = theme.makeChunk(getBeanName());
        chunk.setLocale(rc.getLocale());
        chunk.setMultiple(model);
        chunk.set(rcKey, mapifyRequestContext(rc, request));

        PrintWriter writer = response.getWriter();
        chunk.render(writer);
        writer.flush();
        writer.close();
    }

    private Map<String,String> mapifyRequestContext(RequestContext rc, HttpServletRequest request)
    {
        Map<String,String> rcMap = new HashMap<String,String>();

        // expose some potentially useful info to the template via the {$rc} tag
        rcMap.put("uri", rc.getRequestUri());
        rcMap.put("context_path", rc.getContextPath());
        rcMap.put("servlet_path", rc.getPathToServlet());
        rcMap.put("scheme", request.getScheme());
        rcMap.put("method", request.getMethod());
        rcMap.put("server_name", request.getServerName());
        rcMap.put("remote_addr", request.getRemoteAddr());
        rcMap.put("remote_host", request.getRemoteHost());
        rcMap.put("remote_user", request.getRemoteUser());

        return rcMap;
    }

    private Theme getTheme(String path)
    {
        if (theme == null) {
            Map<String,String> params = new HashMap<String,String>();
            // If no theme path (for include/exec references) is specified
            // in the config, default to the path of the invoked template file.
            params.put(ThemeConfig.THEME_PATH, path);

            Map<String,String> configParams = getConfigParams();
            if (configParams != null) {
                for (String key : configParams.keySet()) {
                    String paramName = key;
                    String paramValue = configParams.get(key);
                    // blank values are considered not-provided
                    if (paramValue != null && paramValue.trim().length() > 0) {
                        params.put(paramName, paramValue);
                    }
                }
            }
            ThemeConfig config = new ThemeConfig(params);
            theme = new Theme(config);
        }

        return theme;
    }

    @SuppressWarnings("unchecked")
    private Map<String,String> getConfigParams()
    {
        try {
            Object config = getApplicationContext().getBean("chunkTemplatesConfig");
            return (Map<String,String>)config;
        } catch (NoSuchBeanDefinitionException e) {
            return null;
        }
    }
}

5. Make a controller! The template name "helloworld" will resolve to /WEB-INF/themes/helloworld.chtml and any include/exec calls will be resolved relative to there.

package com.example.myapp;

import org.springframework.stereotype.Controller;
import org.springframework.ui.Model;
import org.springframework.web.bind.annotation.RequestMapping;
import org.springframework.web.bind.annotation.RequestParam;
import org.springframework.web.servlet.ModelAndView;

@Controller
public class HelloChunk
{
    String message = "Welcome to Spring MVC!";

    @RequestMapping("/hello")
    public ModelAndView showMessage(
            @RequestParam(value = "name", required = false, defaultValue = "World") String name)
    {
        ModelAndView mv = new ModelAndView("helloworld");
        mv.addObject("message", message);
        mv.addObject("name", name);
        mv.addObject("page_name", "Spring 4 MVC - Hello Chunk");
        return mv;
    }

    @RequestMapping(value={"/chunk","/"})
    public ModelAndView chunkTime()
    {
        ModelAndView mv = new ModelAndView("chunkworld");
        mv.addObject("page_name", "Chunky Time");
        return mv;
    }
}