com.owlike.genson

Class Context

java.lang.Object

com.owlike.genson.Context

public class Context
extends Object

The context class is intended to be a statefull class shared across a single execution. Its main purpose is to hold local data and to pass it to others contributors of the serialization/deserialization chain.

For example if you have computed in a first serializer a value and you need it later in another one, you can put it in the context by using store(String, Object) method and later retrieve it with get(String, Class) or remove it with remove(String, Class).

You can achieve the same thing with ThreadLocalHolder that stores the data in a thread local map but it is cleaner to use this Context class as you wont have to worry about removing values from it. Indeed java web servers reuse created threads, so if you store data in a thread local variable and don't remove it, it will still be present when another request comes in and is bound to that thread! This can also lead to memory leaks! Don't forget the try-store-finally-remove block if you stick with ThreadLocalHolder.

This class stores also the views present in the current context, those views will be applied to the matching objects during serialization and deserialization.

Author:

eugen

See Also:

BeanView, BeanViewConverter, ThreadLocalHolder

Field Summary

Fields

Modifier and Type	Field and Description
Genson	genson

Constructor Summary

Constructors

Constructor and Description
Context(Genson genson)
Context(Genson genson, List<Class<? extends BeanView<?>>> views)

Method Summary

Modifier and Type	Method and Description
<T> T	get(String key, Class<T> valueType) Returns the value mapped to key in this context or null.
boolean	hasViews()
<T> T	remove(String key, Class<T> valueType) Removes the mapping for this key from the context.
Object	store(String key, Object o) Puts the object o in the current context indexed by key.
List<Class<? extends BeanView<?>>>	views()
Context	withView(Class<? extends BeanView<?>> view)

Methods inherited from class java.lang.Object

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

Field Detail

genson

public final Genson genson

Constructor Detail

Context

public Context(Genson genson)

Context

public Context(Genson genson,
               List<Class<? extends BeanView<?>>> views)

Method Detail

hasViews

public boolean hasViews()

withView

public Context withView(Class<? extends BeanView<?>> view)

views

public List<Class<? extends BeanView<?>>> views()

store

public Object store(String key,
                    Object o)

Puts the object o in the current context indexed by key.

Parameters:

key - must be not null

o -

Returns:

the old object associated with that key or null.

get

public <T> T get(String key,
                 Class<T> valueType)

Returns the value mapped to key in this context or null. If the value is not of type valueType then an exception is thrown.

Parameters:

key - must be not null

valueType - the type of the value, null not allowed

Returns:

the mapping for key or null

Throws:

ClassCastException - if the value mapped to key is not of type valueType.

remove

public <T> T remove(String key,
                    Class<T> valueType)

Removes the mapping for this key from the context. If there is no mapping for that key, null is returned. If the value mapped to key is not of type valueType an ClassCastException is thrown and the mapping is not removed.

Parameters:

key - must be not null

valueType - the type of the value, null not allowed

Returns:

the value associated to this key

Throws:

ClassCastException - if the value mapped to key is not of type valueType.

See Also:

get(String, Class)