Package groovy.servlet

Class ServletBinding

java.lang.Object

groovy.lang.GroovyObjectSupport

groovy.lang.Binding

groovy.servlet.ServletBinding

All Implemented Interfaces:

GroovyObject

public class ServletBinding
extends Binding

Servlet-specific binding extension to lazy load the writer or the output stream from the response.

Eager variables

• "request" : the HttpServletRequest object
• "response" : the HttpServletRequest object
• "context" : the ServletContext object
• "application" : same as context
• "session" : shorthand for request.getSession(false) - can be null!
• "params" : map of all form parameters - can be empty
• "headers" : map of all request header fields

Lazy variables

• "out" : response.getWriter()
• "sout" : response.getOutputStream()
• "html" : new MarkupBuilder(response.getWriter()) - expandEmptyElements flag is set to true
• "json" : new JsonBuilder()

As per the Servlet specification, a call to response.getWriter() should not be done if a call to response.getOutputStream() has already occurred or the other way around. You may wonder then how the above lazy variables can possibly be provided - since setting them up would involve calling both of the above methods. The trick is catered for behind the scenes using lazy variables. Lazy bound variables can be requested without side effects; under the covers the writer and stream are wrapped. That means response.getWriter() is never directly called until some output is done using 'out' or 'html'. Once a write method call is done using either of these variable, then an attempt to write using 'sout' will cause an IllegalStateException. Similarly, if a write method call on 'sout' has been done already, then any further write method call on 'out' or 'html' will cause an IllegalStateException.

Reserved internal variable names (see "Methods" below)

• "forward"
• "include"
• "redirect"

If response.getWriter() is called directly (without using out), then a write method call on 'sout' will not cause the IllegalStateException, but it will still be invalid. It is the responsibility of the user of this class, to not to mix these different usage styles. The same applies to calling response.getOutputStream() and using 'out' or 'html'.

Methods

• "forward(String path)" : request.getRequestDispatcher(path).forward(request, response)
• "include(String path)" : request.getRequestDispatcher(path).include(request, response)
• "redirect(String location)" : response.sendRedirect(location)

Constructor Summary

Constructors

Constructor	Description
ServletBinding(HttpServletRequest request, HttpServletResponse response, ServletContext context)	Initializes a servlet binding.

Method Summary

Modifier and Type	Method	Description
void	forward(String path)
Object	getVariable(String name)
Map	getVariables()
void	include(String path)
void	redirect(String location)
void	setVariable(String name, Object value)	Sets the value of the given variable

Methods inherited from class groovy.lang.Binding

getProperty, hasVariable, removeVariable, setProperty

Methods inherited from class groovy.lang.GroovyObjectSupport

getMetaClass, setMetaClass

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Methods inherited from interface groovy.lang.GroovyObject

invokeMethod

Constructor Details

ServletBinding

public ServletBinding(HttpServletRequest request,
HttpServletResponse response,
ServletContext context)

Initializes a servlet binding.

Parameters:

request - the HttpServletRequest object

response - the HttpServletRequest object

context - the ServletContext object

Method Details

setVariable

public void setVariable(String name,
Object value)

Description copied from class: Binding

Sets the value of the given variable

Overrides:

setVariable in class Binding

Parameters:

name - the name of the variable to set

value - the new value for the given variable

getVariables

public Map getVariables()

Overrides:

getVariables in class Binding

getVariable

public Object getVariable(String name)

Overrides:

getVariable in class Binding

Parameters:

name - the name of the variable to lookup

Returns:

a writer, an output stream, a markup builder or another requested object

forward

public void forward(String path)
             throws ServletException,
IOException

Throws:

ServletException

IOException

include

public void include(String path)
             throws ServletException,
IOException

Throws:

ServletException

IOException

redirect

public void redirect(String location)
              throws IOException

Throws:

IOException