org.inria.ns.reflex.processor.catalog
Class Builder

java.lang.Object
  org.inria.ns.reflex.processor.catalog.Builder

Direct Known Subclasses:

CatalogBuilder, FilterBuilder, ModuleBuilder, SchemaBuilder, TypeBuilder, XMLBuilder

public abstract class Builder
extends Object

A Builder uses an input to deliver an instance of the object that the input represents. A single builder is not intended to deliver several instances each time the getInstance() method is invoked. However, XMLBuilder seems to waive this principle, because it can deliver either a SAX event producer or a DOM tree ; in fact, both represent the same data model, giving just different APIs ; so the instance delivered is effectively "the same" in a higher point of view.

To deliver an instance, the following steps are performed :

• if the input is a String, a file (XFile), or an URI that starts with "res:" (and not followed by "///"), the remainder is considered as a class name, and an instance of it is delivered; if the class is an interface or an abstract class, a concrete implementation is looked up in the "META-INF/services/" of the Jar libraries available. In any cases, instances are created with the newInstance() static method of the class if it exists, or with the default constructor.
• otherwise, the build() method is invoked to build a new instance with the input.

If an instance of the object can be delivered, next requests should deliver it quickly.

This class is used to provide instances of huge objects stored in a file or in a data base ; for example, EXP modules, catalogs, and schemata are usually backed by a builder. The input is usually a file name, or an URI...

Wrapper

This builder can act as a wrapper if a ready-to-use object is available.

To do so, concrete implementations of this class must fill the protected member #object that will be directly delivered.

Author:

Philippe Poulard

Constructor Summary

Builder(Object name, Object input)
Create a builder from an input.

Method Summary

boolean	equals(Object obj)
Object	getInstance() Return an instance that is represented by the input.
int	hashCode()

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

Builder

public Builder(Object name,
               Object input)

Create a builder from an input.

If a string is given as input, it may be in the following format : "res:org.acme.MyCatalog".

Parameters:

name - The name of the object.

input - The input that will be used to build the instance.

Method Detail

equals

public boolean equals(Object obj)

Overrides:

equals in class Object

See Also:

Object.equals(java.lang.Object)

hashCode

public int hashCode()

Overrides:

hashCode in class Object

See Also:

Object.hashCode()

getInstance

public Object getInstance()
                   throws Exception

Return an instance that is represented by the input.

Once an instance is resolved, this builder always delivers it, except if the reference is a class name (a new instance will be created).

Returns:

The non-null object built now or previously by this builder.

Throws:

Exception - When the input can't be used to build a new instance.