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• ConverterManager.java

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org.databene.commons.converter.ConverterManager Maven / Gradle / Ivy

/*
 * Copyright (C) 2004-2014 Volker Bergmann ([email protected]).
 * All rights reserved.
 *
 * 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 org.databene.commons.converter;

import org.databene.commons.ArrayFormat;
import org.databene.commons.ConfigurationError;
import org.databene.commons.Context;
import org.databene.commons.ConversionException;
import org.databene.commons.Converter;
import org.databene.commons.IOUtil;
import org.databene.commons.BeanUtil;
import org.databene.commons.LogCategories;
import org.databene.commons.OrderedMap;
import org.databene.commons.Patterns;
import org.databene.commons.ReaderLineIterator;
import org.databene.commons.Resettable;
import org.databene.commons.StringUtil;
import org.databene.commons.context.ContextAware;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;

import java.sql.Time;
import java.sql.Timestamp;
import java.text.SimpleDateFormat;
import java.util.*;
import java.io.IOException;
import java.lang.reflect.Array;
import java.lang.reflect.Constructor;
import java.lang.reflect.Method;
import java.lang.reflect.Modifier;

/**
 * Manages converters. A default configuration is provided and can be overwritten by a local file 'converters.txt',
 * that lists each converter's class name, one name per line, e.g.
 * 
 *     com.my.MyString2ThingConverter
 *     com.my.MyString2ComplexConverter
 * 
 * Created: 04.08.2007 19:43:17
 * @author Volker Bergmann
 */
@SuppressWarnings({"unchecked", "rawtypes"})
public class ConverterManager implements ContextAware, Resettable {

	private static final Logger CONFIG_LOGGER = LoggerFactory.getLogger(LogCategories.CONFIG);

    private static final String DEFAULT_SETUP_FILENAME = "org/databene/commons/converter/converters.txt";
    private static final String CUSTOM_SETUP_FILENAME = "converters.txt";

    private static ConverterManager instance;
    private Context context;

	private OrderedMap> configuredConverterClasses;
    
    private Map converterPrototypes;

    private ConverterManager() {
        init();
    }

	protected void init() {
		this.configuredConverterClasses = new OrderedMap>();
        this.converterPrototypes = new HashMap();
        try {
            if (IOUtil.isURIAvailable(CUSTOM_SETUP_FILENAME)) {
            	CONFIG_LOGGER.debug("Reading custom converter config: {}", CUSTOM_SETUP_FILENAME);
                readConfigFile(CUSTOM_SETUP_FILENAME);
            }
            readConfigFile(DEFAULT_SETUP_FILENAME);
        } catch (IOException e) {
            throw new ConfigurationError("Error reading setup file: " + DEFAULT_SETUP_FILENAME);
        }
	}

    public static ConverterManager getInstance() {
        if (instance == null)
            instance = new ConverterManager();
        return instance;
    }

	@Override
	public void setContext(Context context) {
		this.context = context;
		for (Converter converter : converterPrototypes.values())
			injectContext(converter);
	}

	private void injectContext(Converter converter) {
		if (converter instanceof ContextAware)
			((ContextAware) converter).setContext(context);
	}

    public  Converter createConverter(Class sourceType, Class targetType) {
        // check preconditions
        if (targetType == null)
            throw new ConversionException("targetType must be specified");

        // check if we already know how to do this conversion
    	ConversionTypes conversionTypes = new ConversionTypes(sourceType, targetType);
		Converter result = converterPrototypes.get(conversionTypes);
    	if (result != null)
    		return cloneIfSupported(result);

    	// we need to investigate...
        result = searchAppropriateConverter(sourceType, targetType);
        // ...and cache the result for future requests
        if (result != null && result.isParallelizable())
        	converterPrototypes.put(conversionTypes, result);
        
        // inject context if appropriate
        injectContext(result);
        
        // done
        return result;
    }

	private Converter searchAppropriateConverter(Class sourceType, Class targetType) {
		
		// catch primitive types
        Class wrapperClass = BeanUtil.getWrapper(targetType.getName());
        if (wrapperClass != null)
        	return createConverter(sourceType, wrapperClass);

        Converter result;
	    if (targetType.isAssignableFrom(sourceType) && !targetType.isPrimitive())
            return new NoOpConverter();

        // to string conversion
        if (String.class.equals(targetType)) {
            result = createToStringConverter(sourceType);
            if (result != null)
            	return result;
        }

        // from string conversion
        if (String.class.equals(sourceType)) {
        	result = tryToCreateStringConverter(targetType);
        	if (result != null)
        		return result;
        }

        // from number conversion
        if (Number.class.isAssignableFrom(sourceType) && Number.class.isAssignableFrom(targetType))
            return new NumberToNumberConverter(sourceType, targetType);

        // from boolean conversion
        if (Boolean.class.isAssignableFrom(sourceType)) {
        	result = tryToCreateBooleanConverter(targetType);
            if (result != null)
            	return result;
        }

        if (targetType.isArray())
            return new ToArrayConverter(targetType.getComponentType());

        if (Collection.class.isAssignableFrom(targetType))
            return new ToCollectionConverter(targetType);

        result = tryToCreateFactoryConverter(sourceType, targetType);
        if (result != null)
        	return result;
        else
        	throw new ConversionException("Cannot convert " + sourceType.getName() + 
        			" to " + targetType.getName());
    }

	@SuppressWarnings("cast")
    private static Converter tryToCreateStringConverter(Class targetType) {
        if (targetType.getEnumConstants() != null)
            return new String2EnumConverter(targetType);
        else if (targetType == Boolean.class)
            return new String2BooleanConverter();
        else if (Number.class.isAssignableFrom(targetType)) {
        	if (targetType != Number.class)
        		return new String2NumberConverter((Class) targetType);
        	else
        		return new String2NumberConverter(Double.class);
        } else if (targetType.isArray()) {
        	Class componentType = targetType.getComponentType();
        	if (componentType == byte.class)
        		return new String2ByteArrayConverter();
        	else
        		return new CommaSeparatedListConverter(componentType);
        }
        return null;
    }

	private static  Converter tryToCreateBooleanConverter(Class targetType) {
        if (Number.class.isAssignableFrom(targetType))
            return new Boolean2NumberConverter(targetType);
    	Class wrapperClass = BeanUtil.getWrapper(targetType.getName());
		if (wrapperClass != null && Number.class.isAssignableFrom(wrapperClass))
            return new Boolean2NumberConverter(wrapperClass);
		return null;
    }

	private Converter createToStringConverter(Class sourceType) throws ConversionException {
        if (sourceType.isArray()) {
        	Class componentType = sourceType.getComponentType();
			if (componentType == byte.class)
        		return new ByteArrayToBase64Converter();
        	else if (componentType == char.class)
        		return new CharArray2StringConverter();
        	else
        		return new FormatFormatConverter(sourceType, new ArrayFormat(), true);
        } else if (sourceType == Time.class) {
            return new FormatFormatConverter(Time.class, new SimpleDateFormat(Patterns.DEFAULT_TIME_PATTERN), false);
        } else if (sourceType == Timestamp.class) {
            return new TimestampFormatter();
        } else if (sourceType == Date.class) {
            return new FormatFormatConverter(Time.class, new SimpleDateFormat(Patterns.DEFAULT_DATETIME_PATTERN), false);
        } else if (sourceType == Class.class) {
            return new Class2StringConverter();
        } else if (Enum.class.isAssignableFrom(sourceType)) {
            return new Enum2StringConverter(sourceType);
        } else {
        	Converter result = tryToCreateFactoryConverter(sourceType, String.class);
	        if (result != null)
	        	return result;
	        else
	            return new ToStringMethodInvoker(sourceType);
        }
    }

    private Converter tryToCreateFactoryConverter(Class sourceType, Class targetType) {
    	{
	        // find instance method Value() in source type
	        String methodName = StringUtil.uncapitalize(targetType.getSimpleName()) + "Value";
	        Method typeValueMethod = BeanUtil.findMethod(sourceType, methodName, new Class[0]);
	        if (typeValueMethod != null && (typeValueMethod.getModifiers() & Modifier.STATIC) == 0)
	            return new SourceClassMethodInvoker(sourceType, targetType, typeValueMethod);
    	}
    	{
	    	// find static getInstance() method in target type
	        Method getInstanceMethod = BeanUtil.findMethod(targetType, "getInstance", sourceType);
	        if (getInstanceMethod != null && (getInstanceMethod.getModifiers() & Modifier.STATIC) == Modifier.STATIC)
	            return new StaticTargetClassMethodInvoker(sourceType, targetType, getInstanceMethod);
    	}
    	{
	    	// find static valueOf() method in target type
	        Method valueOfMethod = BeanUtil.findMethod(targetType, "valueOf", sourceType);
	        if (valueOfMethod != null && (valueOfMethod.getModifiers() & Modifier.STATIC) == Modifier.STATIC)
	            return new StaticTargetClassMethodInvoker(sourceType, targetType, valueOfMethod);
    	}
    	{
	    	// find target type constructor which takes source type argument
	        Constructor constructor = BeanUtil.findConstructor(targetType, sourceType);
	        if (constructor != null)
	        	return new ConstructorInvoker(sourceType, constructor);
    	}
        return findPoorConfiguredMatch(sourceType, targetType);
    }

	private Converter findPoorConfiguredMatch(Class srcType, Class dstType) {
        if (srcType == dstType || (dstType.isAssignableFrom(srcType) && !dstType.isPrimitive()))
            return new NoOpConverter();
        for (Map.Entry> entry : configuredConverterClasses.entrySet()) {
        	ConversionTypes types = entry.getKey();
            if (types.sourceType == srcType && dstType.isAssignableFrom(types.targetType))
            	return BeanUtil.newInstance(entry.getValue());
        }
        return null;
    }

    public void registerConverterClass(Class converterClass) {
    	Converter converter = BeanUtil.newInstance(converterClass);
        ConversionTypes types = new ConversionTypes(converter);
        configuredConverterClasses.put(types, converterClass);
        if (converter.isParallelizable())
	        converterPrototypes.put(types, converter);
    }
    
    public static  Object convertAll(S[] sourceValues, Converter converter, Class componentType) {
        Object convertedValues = Array.newInstance(componentType, sourceValues.length);
        for (int i = 0; i < sourceValues.length; i++)
            Array.set(convertedValues, i, converter.convert(sourceValues[i]));
        return convertedValues;
    }
    
    public static  Collection convertAll(Collection sourceValues, Converter converter) {
    	List result = new ArrayList(sourceValues.size());
        for (S sourceValue : sourceValues)
            result.add(converter.convert(sourceValue));
        return result;
    }
    
    public static  Converter[] cloneIfSupported(Converter[] prototypes) {
    	Converter[] result = new Converter[prototypes.length];
    	for (int i = 0; i < prototypes.length; i++)
    		result[i] = cloneIfSupported(prototypes[i]);
    	return result;
    }

    public static  Converter cloneIfSupported(Converter prototype) {
        Converter result;
    	if (prototype.isParallelizable())
    		result = BeanUtil.clone(prototype);
    	else if (prototype.isThreadSafe())
    		result = prototype;
    	else
    		result = new SynchronizedConverterProxy(prototype);
        return result;
    }

    // private helpers -------------------------------------------------------------------------------------------------

    private void readConfigFile(String filename) throws IOException {
        ReaderLineIterator iterator = new ReaderLineIterator(IOUtil.getReaderForURI(filename));
        try {
	        while (iterator.hasNext()) {
	            String className = iterator.next();
	            registerConverterClass((Class) Class.forName(className));
	        }
        } catch (ClassNotFoundException e) {
	        throw new ConfigurationError(e);
        } finally {
	        iterator.close();
        }
    }

	@Override
	public void reset() {
		init();
	}

}