TemplateServlet (groovy 2.0.1 API)

java.lang.Object
- javax.servlet.GenericServlet
- - javax.servlet.http.HttpServlet
  - - groovy.servlet.AbstractHttpServlet
    - - groovy.servlet.TemplateServlet

All Implemented Interfaces:

ResourceConnector, java.io.Serializable, javax.servlet.Servlet, javax.servlet.ServletConfig
```
public class TemplateServlet
extends AbstractHttpServlet
```
A generic servlet for serving (mostly HTML) templates.

It delegates work to a groovy.text.TemplateEngine implementation processing HTTP requests.

Usage

helloworld.html is a headless HTML-like template
```
  <html>
    <body>
      <% 3.times { %>
        Hello World!
      <% } %>
      <br>
    </body>
  </html>
 
```
Minimal web.xml example serving HTML-like templates
```
 <web-app>
   <servlet>
     <servlet-name>template</servlet-name>
     <servlet-class>groovy.servlet.TemplateServlet</servlet-class>
   </servlet>
   <servlet-mapping>
     <servlet-name>template</servlet-name>
     <url-pattern>*.html</url-pattern>
   </servlet-mapping>
 </web-app>
 
```
Template engine configuration

By default, the TemplateServer uses the SimpleTemplateEngine which interprets JSP-like templates. The init parameter template.engine defines the fully qualified class name of the template to use:
```
   template.engine = [empty] - equals groovy.text.SimpleTemplateEngine
   template.engine = groovy.text.SimpleTemplateEngine
   template.engine = groovy.text.GStringTemplateEngine
   template.engine = groovy.text.XmlTemplateEngine
 
```
Servlet Init Parameters

Logging and extra-output options

This implementation provides a verbosity flag switching log statements. The servlet init parameter name is:
```
   generated.by = true(default) | false
 
```
Groovy Source Encoding Parameter

The following servlet init parameter name can be used to specify the encoding TemplateServlet will use to read the template groovy source files:
```
   groovy.source.encoding
 
```
See Also:
AbstractHttpServlet.setVariables(ServletBinding), Serialized Form

Field Summary
- Fields inherited from class groovy.servlet.AbstractHttpServlet
  CONTENT_TYPE_TEXT_HTML, encoding, INC_PATH_INFO, INC_REQUEST_URI, INC_SERVLET_PATH, reflection, resourceNameMatcher, resourceNameReplaceAll, resourceNameReplacement, servletContext, verbose

Constructor Summary

Constructors
Constructor and Description

TemplateServlet()
Create new TemplateServlet.

Constructors
Constructor and Description
`TemplateServlet()` Create new TemplateServlet.

Method Summary

Methods
Modifier and Type	Method and Description
`protected Template`	`getTemplate(java.io.File file)` Gets the template created by the underlying engine parsing the request.
`protected Template`	`getTemplate(java.net.URL url)` Gets the template created by the underlying engine parsing the request.
`void`	`init(javax.servlet.ServletConfig config)` Initializes the servlet from hints the container passes.
`protected TemplateEngine`	`initTemplateEngine(javax.servlet.ServletConfig config)` Creates the template engine.
`void`	`service(javax.servlet.http.HttpServletRequest request, javax.servlet.http.HttpServletResponse response)` Services the request with a response.

Methods inherited from class groovy.servlet.AbstractHttpServlet
getResourceConnection, getScriptUri, getScriptUriAsFile, setVariables

Methods inherited from class javax.servlet.http.HttpServlet
doDelete, doGet, doHead, doOptions, doPost, doPut, doTrace, getLastModified, service

Methods inherited from class javax.servlet.GenericServlet
destroy, getInitParameter, getInitParameterNames, getServletConfig, getServletContext, getServletInfo, getServletName, init, log, log

Methods inherited from class java.lang.Object
clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

- Constructor Detail
  - TemplateServlet
```
public TemplateServlet()
```
    Create new TemplateServlet.
- Method Detail
  - getTemplate
```
protected Template getTemplate(java.io.File file)
                        throws javax.servlet.ServletException
```
    Gets the template created by the underlying engine parsing the request.
    This method looks up a simple (weak) hash map for an existing template object that matches the source file. If the source file didn't change in length and its last modified stamp hasn't changed compared to a precompiled template object, this template is used. Otherwise, there is no or an invalid template object cache entry, a new one is created by the underlying template engine. This new instance is put to the cache for consecutive calls.
    
    Parameters:
    file - The file containing the template source.
    
    Returns:
    The template that will produce the response text.
    
    Throws:
    
    javax.servlet.ServletException - If the request specified an invalid template source file
  - getTemplate
```
protected Template getTemplate(java.net.URL url)
                        throws javax.servlet.ServletException
```
    Gets the template created by the underlying engine parsing the request.
    This method looks up a simple (weak) hash map for an existing template object that matches the source URL. If there is no cache entry, a new one is created by the underlying template engine. This new instance is put to the cache for consecutive calls.
    
    Parameters:
    url - The URL containing the template source..
    
    Returns:
    The template that will produce the response text.
    
    Throws:
    
    javax.servlet.ServletException - If the request specified an invalid template source URL
  - init
```
public void init(javax.servlet.ServletConfig config)
          throws javax.servlet.ServletException
```
    Initializes the servlet from hints the container passes.
    Delegates to sub-init methods and parses the following parameters:
    - "generatedBy" : boolean, appends "Generated by ..." to the HTML response text generated by this servlet.
    Specified by:
    
    init in interface javax.servlet.Servlet
    
    Overrides:
    
    init in class AbstractHttpServlet
    
    Parameters:
    config - Passed by the servlet container.
    
    Throws:
    
    javax.servlet.ServletException - if this method encountered difficulties
    See Also:
    initTemplateEngine(ServletConfig)
  - initTemplateEngine
```
protected TemplateEngine initTemplateEngine(javax.servlet.ServletConfig config)
```
    Creates the template engine.
    Called by init(ServletConfig) and returns just new groovy.text.SimpleTemplateEngine() if the init parameter template.engine is not set by the container configuration.
    
    Parameters:
    config - Current servlet configuration passed by the container.
    
    Returns:
    The underlying template engine or null on error.
  - service
```
public void service(javax.servlet.http.HttpServletRequest request,
           javax.servlet.http.HttpServletResponse response)
             throws javax.servlet.ServletException,
                    java.io.IOException
```
    Services the request with a response.
    First the request is parsed for the source file uri. If the specified file could not be found or can not be read an error message is sent as response.
    
    Overrides:
    
    service in class javax.servlet.http.HttpServlet
    
    Parameters:
    request - The http request.
    response - The http response.
    
    Throws:
    
    java.io.IOException - if an input or output error occurs while the servlet is handling the HTTP request
    
    javax.servlet.ServletException - if the HTTP request cannot be handled

Class TemplateServlet

Usage

Template engine configuration

Servlet Init Parameters

Logging and extra-output options

Groovy Source Encoding Parameter

Field Summary

Fields inherited from class groovy.servlet.AbstractHttpServlet

Constructor Summary

Method Summary

Methods inherited from class groovy.servlet.AbstractHttpServlet

Methods inherited from class javax.servlet.http.HttpServlet

Methods inherited from class javax.servlet.GenericServlet

Methods inherited from class java.lang.Object

Constructor Detail

TemplateServlet

Method Detail

getTemplate

getTemplate

init

initTemplateEngine

service