jsonenumconvertor.java

来自「jetty SERVER連接資料庫用的軟體」· Java 代码 · 共 89 行

//========================================================================
//Copyright 2004-2008 Mort Bay Consulting Pty. Ltd.
//------------------------------------------------------------------------
//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.mortbay.util.ajax;

import java.lang.reflect.Method;
import java.util.Map;

import org.mortbay.log.Log;
import org.mortbay.util.Loader;
import org.mortbay.util.ajax.JSON.Output;

/* ------------------------------------------------------------ */
/**
 * Convert an {@link Enum} to JSON.
 * If fromJSON is true in the constructor, the JSON generated will
 * be of the form {class="com.acme.TrafficLight",value="Green"}
 * If fromJSON is false, then only the string value of the enum is generated.
 * @author gregw
 *
 */
public class JSONEnumConvertor implements JSON.Convertor
{
    private boolean _fromJSON;
    private Method _valueOf;
    {
        try
        {
            Class e = Loader.loadClass(getClass(),"java.lang.Enum");
            _valueOf=e.getMethod("valueOf",new Class[]{Class.class,String.class});
        }
        catch(Exception e)
        {
            throw new RuntimeException("!Enums",e);
        }
    }

    public JSONEnumConvertor()
    {
        this(false);
    }
    
    public JSONEnumConvertor(boolean fromJSON)
    {
        _fromJSON=fromJSON;
    }
    
    public Object fromJSON(Map map)
    {
        if (!_fromJSON)
            throw new UnsupportedOperationException();
        try
        {
            Class c=Loader.loadClass(getClass(),(String)map.get("class"));
            return _valueOf.invoke(null,new Object[]{c,map.get("value")});
        }
        catch(Exception e)
        {
            Log.warn(e);  
        }
        return null;
    }

    public void toJSON(Object obj, Output out)
    {
        if (_fromJSON)
        {
            out.addClass(obj.getClass());
            out.add("value",obj.toString());
        }
        else
        {
            out.add(obj.toString());
        }
    }

}