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this has made it the most widely-used Java-based cache.
package com.fasterxml.jackson.databind;
import java.lang.reflect.Type;
import com.fasterxml.jackson.annotation.ObjectIdGenerator;
import com.fasterxml.jackson.databind.annotation.NoClass;
import com.fasterxml.jackson.databind.cfg.HandlerInstantiator;
import com.fasterxml.jackson.databind.cfg.MapperConfig;
import com.fasterxml.jackson.databind.introspect.Annotated;
import com.fasterxml.jackson.databind.introspect.ObjectIdInfo;
import com.fasterxml.jackson.databind.type.TypeFactory;
import com.fasterxml.jackson.databind.util.ClassUtil;
import com.fasterxml.jackson.databind.util.Converter;
/**
* Shared base class for {@link DeserializationContext} and
* {@link SerializerProvider}, context objects passed through data-binding
* process. Designed so that some of implementations can rely on shared
* aspects like access to secondary contextual objects like type factories
* or handler instantiators.
*
* @since 2.2
*/
public abstract class DatabindContext
{
/*
/**********************************************************
/* Generic config access
/**********************************************************
*/
/**
* Accessor to currently active configuration (both per-request configs
* and per-mapper config).
*/
public abstract MapperConfig getConfig();
/**
* Convenience method for accessing serialization view in use (if any); equivalent to:
*
* getConfig().getAnnotationIntrospector();
*
*/
public abstract AnnotationIntrospector getAnnotationIntrospector();
/*
/**********************************************************
/* Access to specific config settings
/**********************************************************
*/
/**
* Convenience method for checking whether specified serialization
* feature is enabled or not.
* Shortcut for:
*
* getConfig().isEnabled(feature);
*
*/
public final boolean isEnabled(MapperFeature feature) {
return getConfig().isEnabled(feature);
}
/**
* Convenience method for accessing serialization view in use (if any); equivalent to:
*
* getConfig().canOverrideAccessModifiers();
*
*/
public final boolean canOverrideAccessModifiers() {
return getConfig().canOverrideAccessModifiers();
}
/**
* Accessor for locating currently active view, if any;
* returns null if no view has been set.
*/
public abstract Class getActiveView();
/*
/**********************************************************
/* Generic attributes (2.3+)
/**********************************************************
*/
/**
* Method for accessing attributes available in this context.
* Per-call attributes have highest precedence; attributes set
* via {@link ObjectReader} or {@link ObjectWriter} have lower
* precedence.
*
* @param key Key of the attribute to get
* @return Value of the attribute, if any; null otherwise
*
* @since 2.3
*/
public abstract Object getAttribute(Object key);
/**
* Method for setting per-call value of given attribute.
* This will override any previously defined value for the
* attribute within this context.
*
* @param key Key of the attribute to set
* @param value Value to set attribute to
*
* @return This context object, to allow chaining
*
* @since 2.3
*/
public abstract DatabindContext setAttribute(Object key, Object value);
/*
/**********************************************************
/* Type instantiation/resolution
/**********************************************************
*/
/**
* Convenience method for constructing {@link JavaType} for given JDK
* type (usually {@link java.lang.Class})
*/
public JavaType constructType(Type type) {
return getTypeFactory().constructType(type);
}
/**
* Convenience method for constructing subtypes, retaining generic
* type parameter (if any)
*/
public JavaType constructSpecializedType(JavaType baseType, Class subclass) {
// simple optimization to avoid costly introspection if type-erased type does NOT differ
if (baseType.getRawClass() == subclass) {
return baseType;
}
return getConfig().constructSpecializedType(baseType, subclass);
}
public abstract TypeFactory getTypeFactory();
/*
/**********************************************************
/* Helper object construction
/**********************************************************
*/
public ObjectIdGenerator objectIdGeneratorInstance(Annotated annotated,
ObjectIdInfo objectIdInfo)
throws JsonMappingException
{
Class implClass = objectIdInfo.getGeneratorType();
final MapperConfig config = getConfig();
HandlerInstantiator hi = config.getHandlerInstantiator();
ObjectIdGenerator gen = (hi == null) ? null : hi.objectIdGeneratorInstance(config, annotated, implClass);
if (gen == null) {
gen = (ObjectIdGenerator) ClassUtil.createInstance(implClass,
config.canOverrideAccessModifiers());
}
return gen.forScope(objectIdInfo.getScope());
}
/**
* Helper method to use to construct a {@link Converter}, given a definition
* that may be either actual converter instance, or Class for instantiating one.
*
* @since 2.2
*/
@SuppressWarnings("unchecked")
public Converter converterInstance(Annotated annotated,
Object converterDef)
throws JsonMappingException
{
if (converterDef == null) {
return null;
}
if (converterDef instanceof Converter) {
return (Converter) converterDef;
}
if (!(converterDef instanceof Class)) {
throw new IllegalStateException("AnnotationIntrospector returned Converter definition of type "
+converterDef.getClass().getName()+"; expected type Converter or Class instead");
}
Class converterClass = (Class)converterDef;
// there are some known "no class" markers to consider too:
if (converterClass == Converter.None.class || converterClass == NoClass.class) {
return null;
}
if (!Converter.class.isAssignableFrom(converterClass)) {
throw new IllegalStateException("AnnotationIntrospector returned Class "
+converterClass.getName()+"; expected Class");
}
final MapperConfig config = getConfig();
HandlerInstantiator hi = config.getHandlerInstantiator();
Converter conv = (hi == null) ? null : hi.converterInstance(config, annotated, converterClass);
if (conv == null) {
conv = (Converter) ClassUtil.createInstance(converterClass,
config.canOverrideAccessModifiers());
}
return (Converter) conv;
}
}