beanmap.java

iBATIS似乎已远离众说纷纭的OR框架之列

     * Get the mappings for this BeanMap
     * 
     * @return BeanMap mappings.  The Set returned by this method
     *         is not modifiable.
     */
    public Set entrySet() {
        return Collections.unmodifiableSet(new AbstractSet() {
            public Iterator iterator() {
                return new Iterator() {

                    Iterator methodIter = 
                      BeanMap.this.readMethods.keySet().iterator();

                    public boolean hasNext() {
                        return methodIter.hasNext();
                    }

                    public Object next() {
                        Object key = (Object)methodIter.next();
                        return new DefaultMapEntry(key, get(key));
                    }

                    public void remove() {
                      throw new UnsupportedOperationException
                        ("remove() not supported from BeanMap.entrySet()");
                    }
                };
            }

            public int size() {
              return BeanMap.this.readMethods.size();
            }
        });
    }

    /**
     * Returns the values for the BeanMap.
     * 
     * @return values for the BeanMap.  The returned collection is not
     *         modifiable.
     */
    public Collection values() {
        ArrayList answer = new ArrayList( readMethods.size() );
        for ( Iterator iter = valueIterator(); iter.hasNext(); ) {
            answer.add( iter.next() );
        }
        return Collections.unmodifiableList(answer);
    }


    // Helper methods
    //-------------------------------------------------------------------------

    /**
     * Returns the type of the property with the given name.
     *
     * @param name  the name of the property
     * @return  the type of the property, or <Code>null</Code> if no such
     *   property exists
     */
    public Class getType(String name) {
        return (Class) types.get( name );
    }

    /**
     *  Convenience method for getting an iterator over the keys.
     *
     *  @return an iterator over the keys
     */
    public Iterator keyIterator() {
        return readMethods.keySet().iterator();
    }

    /**
     *  Convenience method for getting an iterator over the values.
     *
     *  @return an iterator over the values
     */
    public Iterator valueIterator() {
        final Iterator iter = keyIterator();
        return new Iterator() {            
            public boolean hasNext() {
                return iter.hasNext();
            }
            public Object next() {
                Object key = iter.next();
                return get( (String) key );
            }
            public void remove() {
                throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
            }
        };
    }

    /**
     *  Convenience method for getting an iterator over the entries.
     *
     *  @return an iterator over the entries
     */
    public Iterator entryIterator() {
        final Iterator iter = keyIterator();
        return new Iterator() {            
            public boolean hasNext() {
                return iter.hasNext();
            }            
            public Object next() {
                Object key = iter.next();
                Object value = get( (String) key );
                return new MyMapEntry( BeanMap.this, key, value );
            }            
            public void remove() {
                throw new UnsupportedOperationException( "remove() not supported for BeanMap" );
            }
        };
    }


    // Properties
    //-------------------------------------------------------------------------

    /**
     *  Returns the bean currently being operated on.  The return value may
     *  be null if this map is empty.
     *
     *  @return the bean being operated on by this map
     */
    public Object getBean() {
        return bean;
    }

    /**
     *  Sets the bean to be operated on by this map.  The given value may
     *  be null, in which case this map will be empty.
     *
     *  @param newBean  the new bean to operate on
     */
    public void setBean( Object newBean ) {
        bean = newBean;
        reinitialise();
    }


    // Implementation methods
    //-------------------------------------------------------------------------

    /**
     *  Returns the accessor for the property with the given name.
     *
     *  @param name  the name of the property 
     *  @return null if the name is null; null if the name is not a 
     *  {@link String}; null if no such property exists; or the accessor
     *   method for that property
     */
    protected Method getReadMethod( Object name ) {
        return (Method) readMethods.get( name );
    }

    /**
     *  Returns the mutator for the property with the given name.
     *
     *  @param name  the name of the 
     *  @return null if the name is null; null if the name is not a 
     *  {@link String}; null if no such property exists; null if the 
     *  property is read-only; or the mutator method for that property
     */
    protected Method getWriteMethod( Object name ) {
        return (Method) writeMethods.get( name );
    }

    /**
     *  Reinitializes this bean.  Called during {@link #setBean(Object)}.
     *  Does introspection to find properties.
     */
    protected void reinitialise() {
        readMethods.clear();
        writeMethods.clear();
        types.clear();
        initialise();
    }

    private void initialise() {
        if(getBean() == null) return;

        Class  beanClass = getBean().getClass();
        try {
            //BeanInfo beanInfo = Introspector.getBeanInfo( bean, null );
            BeanInfo beanInfo = Introspector.getBeanInfo( beanClass );
            PropertyDescriptor[] propertyDescriptors = beanInfo.getPropertyDescriptors();
            if ( propertyDescriptors != null ) {
                for ( int i = 0; i < propertyDescriptors.length; i++ ) {
                    PropertyDescriptor propertyDescriptor = propertyDescriptors[i];
                    if ( propertyDescriptor != null ) {
                        String name = propertyDescriptor.getName();
                        Method readMethod = propertyDescriptor.getReadMethod();
                        Method writeMethod = propertyDescriptor.getWriteMethod();
                        Class aType = propertyDescriptor.getPropertyType();

                        if ( readMethod != null ) {
                            readMethods.put( name, readMethod );
                        }
                        if ( writeMethods != null ) {
                            writeMethods.put( name, writeMethod );
                        }
                        types.put( name, aType );
                    }
                }
            }
        }
        catch ( IntrospectionException e ) {
            logWarn(  e );
        }
    }

    /**
     *  Called during a successful {@link #put(Object,Object)} operation.
     *  Default implementation does nothing.  Override to be notified of
     *  property changes in the bean caused by this map.
     *
     *  @param key  the name of the property that changed
     *  @param oldValue  the old value for that property
     *  @param newValue  the new value for that property
     */
    protected void firePropertyChange( Object key, Object oldValue, Object newValue ) {
    }

    // Implementation classes
    //-------------------------------------------------------------------------

    /**
     *  Map entry used by {@link BeanMap}.
     */
    protected static class MyMapEntry extends DefaultMapEntry {        
        private BeanMap owner;
        
        /**
         *  Constructs a new <Code>MyMapEntry</Code>.
         *
         *  @param owner  the BeanMap this entry belongs to
         *  @param key  the key for this entry
         *  @param value  the value for this entry
         */
        protected MyMapEntry( BeanMap owner, Object key, Object value ) {
            super( key, value );
            this.owner = owner;
        }

        /**
         *  Sets the value.
         *
         *  @param value  the new value for the entry
         *  @return the old value for the entry
         */
        public Object setValue(Object value) {
            Object key = getKey();
            Object oldValue = owner.get( key );

            owner.put( key, value );
            Object newValue = owner.get( key );
            super.setValue( newValue );
            return oldValue;
        }
    }

    /**
     *  Creates an array of parameters to pass to the given mutator method.
     *  If the given object is not the right type to pass to the method 
     *  directly, it will be converted using {@link #convertType(Class,Object)}.
     *
     *  @param method  the mutator method
     *  @param value  the value to pass to the mutator method
     *  @return an array containing one object that is either the given value
     *    or a transformed value
     *  @throws IllegalAccessException if {@link #convertType(Class,Object)}
     *    raises it
     *  @throws IllegalArgumentException if any other exception is raised
     *    by {@link #convertType(Class,Object)}
     */
    protected Object[] createWriteMethodArguments( Method method, Object value ) throws IllegalAccessException, ClassCastException {            
        try {
            if ( value != null ) {
                Class[] types = method.getParameterTypes();
                if ( types != null && types.length > 0 ) {
                    Class paramType = types[0];
                    if ( ! paramType.isAssignableFrom( value.getClass() ) ) {
                        value = convertType( paramType, value );
                    }
                }
            }
            Object[] answer = { value };
            return answer;
        }
        catch ( InvocationTargetException e ) {
            logInfo( e );
            throw new IllegalArgumentException( e.getMessage() );
        }
        catch ( InstantiationException e ) {
            logInfo( e );
            throw new IllegalArgumentException( e.getMessage() );
        }
    }

    /**
     * Converts the given value to the given type.  First, reflection is
     * is used to find a public constructor declared by the given class 
     * that takes one argument, which must be the precise type of the 
     * given value.  If such a constructor is found, a new object is
     * created by passing the given value to that constructor, and the
     * newly constructed object is returned.<P>
     *
     * If no such constructor exists, and the given type is a primitive
     * type, then the given value is converted to a string using its 
     * {@link Object#toString() toString()} method, and that string is
     * parsed into the correct primitve type using, for instance, 
     * {@link Integer#valueOf(String)} to convert the string into an
     * <Code>int</Code>.<P>
     *
     * If no special constructor exists and the given type is not a 
     * primitive type, this method returns the original value.
     *
     * @param newType  the type to convert the value to
     * @param value  the value to conert
     * @return the converted value
     * @throws NumberFormatException if newType is a primitive type, and 
     *   the string representation of the given value cannot be converted
     *   to that type
     * @throws InstantiationException  if the constructor found with 
     *   reflection raises it
     * @throws InvocationTargetExcetpion  if the constructor found with
     *   reflection raises it
     * @throws IllegalAccessException  never
     * @throws IllegalArgumentException  never
     */
    protected Object convertType( Class newType, Object value ) 
        throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException {
        
        // try call constructor
        Class[] types = { value.getClass() };
        try {
            Constructor constructor = newType.getConstructor( types );        
            Object[] arguments = { value };
            return constructor.newInstance( arguments );
        }
        catch ( NoSuchMethodException e ) {
            // try using the transformers
            Transformer transformer = getTypeTransformer( newType );
            if ( transformer != null ) {
                return transformer.transform( value );
            }
            return value;
        }
    }

    /**
     *  Returns a transformer for the given primitive type.
     *
     *  @param aType  the primitive type whose transformer to return
     *  @return a transformer that will convert strings into that type,
     *   or null if the given type is not a primitive type
     */
    protected Transformer getTypeTransformer( Class aType ) {
        return (Transformer) defaultTransformers.get( aType );
    }

    /**
     *  Logs the given exception to <Code>System.out</Code>.  Used to display
     *  warnings while accessing/mutating the bean.
     *
     *  @param e  the exception to log
     */
    protected void logInfo(Exception e) {
        // XXXX: should probably use log4j here instead...
        System.out.println( "INFO: Exception: " + e );
    }

    /**
     *  Logs the given exception to <Code>System.err</Code>.  Used to display
     *  errors while accessing/mutating the bean.
     *
     *  @param e  the exception to log
     */
    protected void logWarn(Exception e) {
        // XXXX: should probably use log4j here instead...
        System.out.println( "WARN: Exception: " + e );
        e.printStackTrace();
    }
}