rapladefaultcontext.java

来自「Rapla是一个灵活的多用户资源管理系统。它提供的一些功能有：日历GUI」· Java 代码 · 共 73 行

package org.rapla.framework;

import java.util.HashMap;



public class RaplaDefaultContext
    implements RaplaContext
{
    private final HashMap contextObjects = new HashMap();
    private final RaplaContext m_parent;

    public RaplaDefaultContext()
    {
        this( null );
    }

    public RaplaDefaultContext( final RaplaContext parent )
    {
        m_parent = parent;
    }


    public Object lookup( final String key )
        throws RaplaContextException
    {
        final Object object = contextObjects.get( key );
        if( null != object )
        {
            return object;
        }
        else if( null != m_parent )
        {
            return m_parent.lookup( key );
        }
        else
        {
            final String message = "Unable to provide implementation for " + key;
            throw new RaplaContextException( key, message, null );
        }
    }


    public boolean has( final String key )
    {
        if (contextObjects.get( key ) != null)
            return true;

        if ( m_parent == null)
            return false;

        return m_parent.has( key );
    }

    public void put( final String key, final Object object )
    {
        contextObjects.put( key, object );
    }


    protected Object getUnsave(String key) {
        if ( has( key)) {
            try {
                return lookup( key  );
            } catch (RaplaContextException ex) {
            }
        }
        return null;
    }


}