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//========================================================================
//Copyright 2007-2011 David Yu [email protected]
//------------------------------------------------------------------------
//Licensed under the Apache License, Version 2.0 (the "License");
//you may not use this file except in compliance with the License.
//You may obtain a copy of the License at 
//http://www.apache.org/licenses/LICENSE-2.0
//Unless required by applicable law or agreed to in writing, software
//distributed under the License is distributed on an "AS IS" BASIS,
//WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
//See the License for the specific language governing permissions and
//limitations under the License.
//========================================================================

package com.dyuproject.protostuff.runtime;

import java.lang.reflect.Constructor;
import java.lang.reflect.InvocationTargetException;
import java.lang.reflect.Method;
import java.util.Properties;

/**
 * The runtime environment.
 *
 * @author David Yu
 * @created Jul 8, 2011
 */
public final class RuntimeEnv
{
    /**
     * Returns true if serializing enums by name is activated.
     * Disabled by default.
     * When the enum's values have no @Tag annotation, this strategy is used.
     * For more flexibility, annotate the enums with @Tag annotation so that based on the
     * type of output the values will be written by their name or number.
     */
    public static final boolean ENUMS_BY_NAME;
    
    /**
     * Enabled by default.  For security purposes, you probably would want to 
     * register all known classes and disable this option.
     */
    public static final boolean AUTO_LOAD_POLYMORPHIC_CLASSES;
    
    /**
     * Disabled by default. Writes a sentinel value (uint32) in place of null values. Works only on the binary formats
     * (protostuff/graph/protobuf).
     */
    public static final boolean ALLOW_NULL_ARRAY_ELEMENT;
    
    /**
     * Disabled by default.  For pojos that are not declared final, they 
     * could still be morphed to their respective subclasses (inheritance).
     * Enable this option if your parent classes aren't abstract classes.
     */
    public static final boolean MORPH_NON_FINAL_POJOS;
    
    /**
     * Disabled by default.  If true, type metadata will be included on serialization 
     * for fields that are collection interfaces. 
     * Enabling this is useful if you want to retain the actual collection impl used.
     * 
     * If disabled, type metadata will not be included and instead, will be mapped 
     * to a default impl.
     * 
     * Collection = ArrayList
     * List = ArrayList
     * Set = HashSet
     * SortedSet = TreeSet
     * NavigableSet = TreeSet
     * Queue = LinkedList
     * BlockingQueue = LinkedBlockingQueue
     * Deque = LinkedList
     * BlockingDequeue = LinkedBlockingDeque
     * 

     * 
     * You can optionally enable only for a particular field by annotation it with 
     * {@link com.dyuproject.protostuff.Morph}.
     */
    public static final boolean MORPH_COLLECTION_INTERFACES;
    
    /**
     * Disabled by default.  If true, type metadata will be included on serialization 
     * for fields that are map interfaces. 
     * Enabling this is useful if you want to retain the actual map impl used.
     * 
     * If disabled, type metadata will not be included and instead, will be mapped 
     * to a default impl.
     * 
     * Map = HashMap
     * SortedMap = TreeMap
     * NavigableMap = TreeMap
     * ConcurrentMap = ConcurrentHashMap
     * ConcurrentNavigableMap = ConcurrentSkipListMap
     * 

     * 
     * You can optionally enable only for a particular field by annotation it with 
     * {@link com.dyuproject.protostuff.Morph}.
     */
    public static final boolean MORPH_MAP_INTERFACES;
    
    /**
     * On repeated fields, the List/Collection itself is not serialized (only its values).
     * If you enable this option, the repeated field will be serialized as a 
     * standalone message with a collection schema.  Even if the List/Collection is empty, 
     * an empty collection message is still written.
     * 
     * This is particularly useful if you rely on {@link Object#equals(Object)} on your 
     * pojos.
     * 
     * Disabled by default for protobuf compatibility.
     */
    public static final boolean COLLECTION_SCHEMA_ON_REPEATED_FIELDS;
    
    /**
     * If true, sun.misc.Unsafe is used to access the fields of the objects instead of 
     * plain java reflections.  Enabled by default if running on a sun jre.
     */
    public static final boolean USE_SUN_MISC_UNSAFE;
    
    /**
     * If true, an existing message schema is used instead of creating a new one.
     * This is useful when mixing pre-compiled/generated pojos.
     * Enabled by default.
     */
    public static final boolean MIX_MESSAGE_SCHEMA;
    
    
    /**
     * If true, the constructor will always be obtained from 
     * {@code ReflectionFactory.newConstructorFromSerialization}.
     * 
     * Disabled by default, which means that if the pojo has a no-args constructor, 
     * that will be used instead.
     * 
     * Enable this if you intend to avoid deserializing objects whose no-args constructor 
     * initializes (unwanted) internal state.  This applies to complex/framework objects.
     * 
     * If you intend to fill default field values using your default constructor, 
     * leave this disabled. This normally applies to java beans/data objects.
     */
    public static final boolean ALWAYS_USE_SUN_REFLECTION_FACTORY;
    
    static final Method newInstanceFromObjectInputStream;
    
    static final Constructor OBJECT_CONSTRUCTOR;
    
    public static final IdStrategy ID_STRATEGY;
    
    static
    {
        Constructor c = null;
        Class reflectionFactoryClass = null;
        try
        {
            c = Object.class.getConstructor((Class[])null);
            reflectionFactoryClass = Thread.currentThread().getContextClassLoader()
                    .loadClass("sun.reflect.ReflectionFactory");
        }
        catch (Exception e)
        {
            // ignore
        }
        
        OBJECT_CONSTRUCTOR = c != null && reflectionFactoryClass != null ? c : null;
        
        newInstanceFromObjectInputStream = OBJECT_CONSTRUCTOR == null ? 
                getMethodNewInstanceFromObjectInputStream() : null;
                
        if(newInstanceFromObjectInputStream != null)
            newInstanceFromObjectInputStream.setAccessible(true);
        
        Properties props = OBJECT_CONSTRUCTOR == null ? new Properties() : 
            System.getProperties();
        
        ENUMS_BY_NAME = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.enums_by_name", "false"));
        
        AUTO_LOAD_POLYMORPHIC_CLASSES = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.auto_load_polymorphic_classes", "true"));
        
        ALLOW_NULL_ARRAY_ELEMENT = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.allow_null_array_element", "false"));
        
        MORPH_NON_FINAL_POJOS = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.morph_non_final_pojos", "false"));
        
        MORPH_COLLECTION_INTERFACES = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.morph_collection_interfaces", "false"));
        
        MORPH_MAP_INTERFACES = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.morph_map_interfaces", "false"));
        
        COLLECTION_SCHEMA_ON_REPEATED_FIELDS = Boolean.parseBoolean(props.getProperty(
                "protostuff.runtime.collection_schema_on_repeated_fields", "false"));
        
        // must be on a sun jre
        USE_SUN_MISC_UNSAFE = OBJECT_CONSTRUCTOR != null && Boolean.parseBoolean(
                props.getProperty("protostuff.runtime.use_sun_misc_unsafe", "true"));
        
        ALWAYS_USE_SUN_REFLECTION_FACTORY = OBJECT_CONSTRUCTOR != null && 
                Boolean.parseBoolean(props.getProperty(
                        "protostuff.runtime.always_use_sun_reflection_factory", "false"));
        
        MIX_MESSAGE_SCHEMA = Boolean.parseBoolean(props.getProperty(
            "protostuff.runtime.mix_message_schema", "true"));
        
        String factoryProp = props.getProperty(
                "protostuff.runtime.id_strategy_factory");
        if(factoryProp == null)
            ID_STRATEGY = new DefaultIdStrategy();
        else
        {
            final IdStrategy.Factory factory;
            try
            {
                factory = ((IdStrategy.Factory)loadClass(factoryProp).newInstance());
            }
            catch (Exception e)
            {
                throw new RuntimeException(e);
            }
            
            ID_STRATEGY = factory.create();
            factory.postCreate();
        }
    }
    
    private static Method getMethodNewInstanceFromObjectInputStream()
    {
        try
        {
            return java.io.ObjectInputStream.class.getDeclaredMethod(
                    "newInstance", Class.class, Class.class);
        }
        catch(Exception e)
        {
            return null;
        }
    }
    
    @SuppressWarnings("unchecked")
    static  Class loadClass(String className)
    {
        try
        {
            return (Class)Thread.currentThread().getContextClassLoader().loadClass(
                    className);
        }
        catch (ClassNotFoundException e)
        {
            throw new RuntimeException(e);
        }
    }
    
    /**
     * Returns an instatiator for the specified {@code clazz}.
     */
    public static  Instantiator newInstantiator(Class clazz)
    {
        final Constructor constructor = getConstructor(clazz);
        if(constructor == null)
        {
            // non-sun jre
            if(newInstanceFromObjectInputStream == null)
                throw new RuntimeException("Could not resolve constructor for " + clazz);
            
            return new Android2Instantiator(clazz);
        }
        
        return new DefaultInstantiator(constructor);
    }
    
    private static  Constructor getConstructor(Class clazz)
    {
        if(ALWAYS_USE_SUN_REFLECTION_FACTORY)
            return OnDemandSunReflectionFactory.getConstructor(clazz, OBJECT_CONSTRUCTOR);
        
        try
        {
            return clazz.getDeclaredConstructor((Class[])null);
        }
        catch (SecurityException e)
        {
            return OBJECT_CONSTRUCTOR == null ? null : 
                OnDemandSunReflectionFactory.getConstructor(clazz, OBJECT_CONSTRUCTOR);
        }
        catch (NoSuchMethodException e)
        {
            return OBJECT_CONSTRUCTOR == null ? null : 
                OnDemandSunReflectionFactory.getConstructor(clazz, OBJECT_CONSTRUCTOR);
        }
    }
    
    
    private RuntimeEnv() {}
    
    public static abstract class Instantiator
    {
        /**
         * Creates a new instance of an object.
         */
        public abstract T newInstance();
    }
    
    static final class DefaultInstantiator extends Instantiator
    {
        
        final Constructor constructor;
        
        DefaultInstantiator(Constructor constructor)
        {
            this.constructor = constructor;
            constructor.setAccessible(true);
        }

        public T newInstance()
        {
            try
            {
                return constructor.newInstance((Object[])null);
            }
            catch (IllegalArgumentException e)
            {
                throw new RuntimeException(e);
            }
            catch (InstantiationException e)
            {
                throw new RuntimeException(e);
            }
            catch (IllegalAccessException e)
            {
                throw new RuntimeException(e);
            }
            catch (InvocationTargetException e)
            {
                throw new RuntimeException(e);
            }
        }
    }
    
    static final class Android2Instantiator extends Instantiator
    {
        
        final Class clazz;
        
        Android2Instantiator(Class clazz)
        {
            this.clazz = clazz;
        }

        @SuppressWarnings("unchecked")
        public T newInstance()
        {
            try
            {
                return (T)newInstanceFromObjectInputStream.invoke(null, 
                        clazz, Object.class);
            }
            catch (IllegalArgumentException e)
            {
                throw new RuntimeException(e);
            }
            catch (IllegalAccessException e)
            {
                throw new RuntimeException(e);
            }
            catch (InvocationTargetException e)
            {
                throw new RuntimeException(e);
            }
        }
    }

}
    

    

    

            

    

            



    
    






    
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