defaultconvertermanager.java

Ajax 框架,可以用来做数型菜单或者联动下拉列表

/*
 * Copyright 2005 Joe Walker
 *
 * 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.directwebremoting.dwrp;

import java.util.Arrays;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

import org.directwebremoting.Converter;
import org.directwebremoting.ConverterManager;
import org.directwebremoting.InboundContext;
import org.directwebremoting.InboundVariable;
import org.directwebremoting.MarshallException;
import org.directwebremoting.OutboundContext;
import org.directwebremoting.OutboundVariable;
import org.directwebremoting.TypeHintContext;
import org.directwebremoting.util.LocalUtil;
import org.directwebremoting.util.Logger;
import org.directwebremoting.util.Messages;

/**
 * A class to manage the converter types and the instansiated class name matches.
 * @author Joe Walker [joe at getahead dot ltd dot uk]
 */
public class DefaultConverterManager implements ConverterManager
{
    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#addConverterType(java.lang.String, java.lang.String)
     */
    public void addConverterType(String id, String className)
    {
        Class clazz = LocalUtil.classForName(id, className, Converter.class);
        if (clazz != null)
        {
            converterTypes.put(id, clazz);
        }
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#addConverter(java.lang.String, java.lang.String, java.util.Map)
     */
    public void addConverter(String match, String type, Map params) throws IllegalArgumentException, InstantiationException, IllegalAccessException
    {
        Class clazz = (Class) converterTypes.get(type);
        if (clazz == null)
        {
            log.info("Type '" + match + "' is not convertable due to missing converter '" + type + "'. This is only an problem if you wanted to use it."); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
            return;
        }

        Converter converter = (Converter) clazz.newInstance();
        converter.setConverterManager(this);

        LocalUtil.setParams(converter, params, ignore);

        // add the converter for the specified match
        addConverter(match, converter);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#addConverter(java.lang.String, org.directwebremoting.Converter)
     */
    public void addConverter(String match, Converter converter) throws IllegalArgumentException
    {
        // Check that we don't have this one already
        Converter other = (Converter) converters.get(match);
        if (other != null)
        {
            log.warn("Clash of converters for " + match + ". Using " + converter.getClass().getName() + " in place of " + other.getClass().getName()); //$NON-NLS-1$ //$NON-NLS-2$ //$NON-NLS-3$
        }

        converters.put(match, converter);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#isConvertable(java.lang.Class)
     */
    public boolean isConvertable(Class paramType)
    {
        return getConverter(paramType) != null;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#convertInbound(java.lang.Class, org.directwebremoting.InboundVariable, org.directwebremoting.InboundContext, org.directwebremoting.TypeHintContext)
     */
    public Object convertInbound(Class paramType, InboundVariable iv, InboundContext inctx, TypeHintContext incc) throws MarshallException
    {
        Object converted = inctx.getConverted(iv, paramType);
        if (converted == null)
        {
            Converter converter = getConverter(paramType);
            if (converter == null)
            {
                throw new MarshallException(Messages.getString("DefaultConverterManager.MissingConverter", paramType.getName())); //$NON-NLS-1$
            }

            // We only think about doing a null conversion ourselves once we are
            // sure that there is a converter available. This prevents hackers
            // from passing null to things they are not allowed to convert
            if (iv.isNull())
            {
                return null;
            }

            // TODO: push the push/pop inside the converters?
            inctx.pushContext(incc);
            converted = converter.convertInbound(paramType, iv, inctx);
            inctx.popContext();
        }

        return converted;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#convertOutbound(java.lang.Object, org.directwebremoting.OutboundContext)
     */
    public OutboundVariable convertOutbound(Object object, OutboundContext converted) throws MarshallException
    {
        if (object == null)
        {
            return new OutboundVariable("", "null"); //$NON-NLS-1$ //$NON-NLS-2$
        }

        // Check to see if we have done this one already
        OutboundVariable ov = converted.get(object);
        if (ov != null)
        {
            // So the object as been converted already, we just need to refer to it.
            return new OutboundVariable("", ov.getAssignCode()); //$NON-NLS-1$
        }

        // So we will have to do the conversion
        Converter converter = getConverter(object);
        if (converter == null)
        {
            log.error(Messages.getString("DefaultConverterManager.MissingConverter", object.getClass().getName())); //$NON-NLS-1$
            String varName = converted.getNextVariableName();
            return new OutboundVariable("var " + varName + "=null;", varName); //$NON-NLS-1$ //$NON-NLS-2$
        }

        return converter.convertOutbound(object, converted);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#setExtraTypeInfo(org.directwebremoting.TypeHintContext, java.lang.Class)
     */
    public void setExtraTypeInfo(TypeHintContext thc, Class type)
    {
        extraTypeInfoMap.put(thc, type);
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#getExtraTypeInfo(org.directwebremoting.TypeHintContext)
     */
    public Class getExtraTypeInfo(TypeHintContext thc)
    {
        Class type = (Class) extraTypeInfoMap.get(thc);
        return type;
    }

    /* (non-Javadoc)
     * @see org.directwebremoting.ConverterManager#setConverters(java.util.Map)
     */
    public void setConverters(Map converters)
    {
        this.converters = converters;
    }

    /**
     * Like <code>getConverter(object.getClass());</code> except that since the
     * object can be null we check for that fist and then do a lookup against
     * the <code>Void.TYPE</code> converter
     * @param object The object to find a converter for
     * @return The converter for the given type
     */
    private Converter getConverter(Object object)
    {
        if (object == null)
        {
            return getConverter(Void.TYPE);
        }

        return getConverter(object.getClass());
    }

    /**
     * @param paramType The type to find a converter for
     * @return The converter for the given type, or null if one can't be found
     */
    private Converter getConverter(Class paramType)
    {
        // Can we find a converter assignable to paramType in the HashMap?
        Converter converter = getConverterAssignableFrom(paramType);
        if (converter != null)
        {
            return converter;
        }

        String lookup = paramType.getName();

        // Before we start trying for a match on package parts we check for
        // dynamic proxies
        if (lookup.startsWith("$Proxy")) //$NON-NLS-1$
        {
            converter = (Converter) converters.get("$Proxy*"); //$NON-NLS-1$
            if (converter != null)
            {
                return converter;
            }
        }

        while (true)
        {
            // Can we find a converter using wildcards?
            converter = (Converter) converters.get(lookup + ".*"); //$NON-NLS-1$
            if (converter != null)
            {
                return converter;
            }

            // Arrays can have wildcards like [L* so we don't require a '.'
            converter = (Converter) converters.get(lookup + '*');
            if (converter != null)
            {
                return converter;
            }

            // Give up if the name is now empty
            if (lookup.length() == 0)
            {
                break;
            }

            // Strip of the component after the last .
            int lastdot = lookup.lastIndexOf('.');
            if (lastdot != -1)
            {
                lookup = lookup.substring(0, lastdot);
            }
            else
            {
                int arrayMarkers = 0;
                while (lookup.charAt(arrayMarkers) == '[')
                {
                    arrayMarkers++;
                }

                if (arrayMarkers == 0)
                {
                    // so we are out of dots and out of array markers
                    // bail out.
                    break;
                }

                // We want to keep the type marker too
                lookup = lookup.substring(arrayMarkers - 1, arrayMarkers + 1);

                // Now can we find it?
                converter = (Converter) converters.get(lookup);
                if (converter != null)
                {
                    return converter;
                }                
            }
        }

        return null;
    }

    /**
     * @param paramType The type to find a converter for
     * @return The converter assignable for the given type, or null if one can't be found
     */
    private Converter getConverterAssignableFrom(Class paramType)
    {
        if (paramType == null)
        {
            return null;
        }

        String lookup = paramType.getName();

        // Can we find the converter for paramType in the converters HashMap?
        Converter converter = (Converter) converters.get(lookup);
        if (converter != null)
        {
            return converter;
        }

        // Lookup all of the interfaces of this class for a match
        Class[] interfaces = paramType.getInterfaces();
        for (int i = 0; i < interfaces.length; i++)
        {
            converter = getConverterAssignableFrom(interfaces[i]);
            if (converter != null)
            {
                converters.put(lookup, converter);
                return converter;
            }
        }

        // Let's search it in paramType superClass
        converter = getConverterAssignableFrom(paramType.getSuperclass());
        if (converter != null)
        {
            converters.put(lookup, converter);
        }

        return converter;
    }

    /**
     * Where we store real type information behind generic types
     */
    private Map extraTypeInfoMap = new HashMap();

    /**
     * The log stream
     */
    private static final Logger log = Logger.getLogger(DefaultConverterManager.class);

    /**
     * The list of the available converters
     */
    private Map converterTypes = new HashMap();

    /**
     * The list of the configured converters
     */
    private Map converters = new HashMap();

    /**
     * The properties that we don't warn about if they don't exist.
     * @see DefaultConverterManager#addConverter(String, String, Map)
     */
    private static List ignore = Arrays.asList(new String[] { "converter", "match" }); //$NON-NLS-1$ //$NON-NLS-2$
}