com.google.common.base.Function#apply ( )源码实例Demo

private static Predicate<Entry> or(List<String> queries, Function<String, Predicate<Entry>> transform) {
   Preconditions.checkNotNull(transform);
   if(queries == null || queries.isEmpty()) {
      return Predicates.alwaysTrue();
   }
   List<Predicate<Entry>> predicates = new ArrayList<>(queries.size());
   for(String query: queries) {
      Predicate<Entry> p = transform.apply(query);
      if(p != null) {
         predicates.add(p);
      }
   }
   if(predicates.isEmpty()) {
      return Predicates.alwaysTrue();
   }
   else if(predicates.size() == 1) {
      return predicates.get(0);
   }
   else {
      return Predicates.or(predicates);
   }
}
 

/**
 * 内部转换 List
 *
 * @param fromList   来源list
 * @param function   转换工具
 * @param filterNull 是否过滤null值
 * @param <F>        入参对象
 * @param <T>        出参对象
 * @return 返回转换后的列表
 */
private static <F, T> List<T> transformInner(List<F> fromList,
                                             Function<? super F, ? extends T> function,
                                             boolean filterNull) {
    if (CollectionUtils.isEmpty(fromList)) {
        return new ArrayList<T>(0);
    }

    List<T> resultList = new ArrayList<T>(fromList.size());
    for (F f : fromList) {
        T data = function.apply(f);
        if (filterNull && data == null) {
            continue;
        }
        resultList.add(data);
    }
    return resultList;
}
 

/**
 * Uses the render context to create a compact shape for the given vertex
 * 
 * @param rc the render context
 * @param layout the layout
 * @param vertex the vertex
 * @return the vertex shape
 * @see VertexShapeProvider#getCompactShape()
 */
protected Shape getCompactShape(RenderContext<V, E> rc, Layout<V, E> layout, V vertex) {

	Function<? super V, Shape> vertexShaper = rc.getVertexShapeTransformer();
	Shape shape = null;
	if (vertexShaper instanceof VisualGraphVertexShapeTransformer) {
		@SuppressWarnings("unchecked")
		VisualGraphVertexShapeTransformer<V> vgShaper =
			(VisualGraphVertexShapeTransformer<V>) vertexShaper;

		// use the viewable shape here, as it is visually pleasing
		shape = vgShaper.transformToCompactShape(vertex);
	}
	else {
		shape = vertexShaper.apply(vertex);
	}

	return transformFromLayoutToView(rc, layout, vertex, shape);
}
 

protected void paintScaledVertex(RenderContext<V, E> rc, V vertex, GraphicsDecorator g,
		Shape shape) {
	Function<? super V, Paint> fillXform = rc.getVertexFillPaintTransformer();
	Paint fillPaint = fillXform.apply(vertex);
	if (fillPaint == null) {
		return;
	}

	Paint oldPaint = g.getPaint();
	g.setPaint(fillPaint);
	g.fill(shape);

	// an outline
	g.setColor(Color.BLACK);
	g.draw(shape);

	g.setPaint(oldPaint);
}
 

/**
 * Uses the render context to create a compact shape for the given vertex
 * 
 * @param rc the render context
 * @param layout the layout
 * @param vertex the vertex
 * @return the vertex shape
 * @see VertexShapeProvider#getCompactShape()
 */
protected Shape getCompactShape(RenderContext<V, E> rc, Layout<V, E> layout, V vertex) {

	Function<? super V, Shape> vertexShaper = rc.getVertexShapeTransformer();
	Shape shape = null;
	if (vertexShaper instanceof VisualGraphVertexShapeTransformer) {
		@SuppressWarnings("unchecked")
		VisualGraphVertexShapeTransformer<V> vgShaper =
			(VisualGraphVertexShapeTransformer<V>) vertexShaper;

		// use the viewable shape here, as it is visually pleasing
		shape = vgShaper.transformToCompactShape(vertex);
	}
	else {
		shape = vertexShaper.apply(vertex);
	}

	return transformFromLayoutToView(rc, layout, vertex, shape);
}
 

private static <V extends VisualVertex, E extends VisualEdge<V>> Function<V, Rectangle> 
	createVertexToBoundsTransformer(VisualizationServer<V, E> viewer) {
//@formatter:on

	RenderContext<V, E> context = viewer.getRenderContext();
	Function<? super V, Shape> shapeTransformer = context.getVertexShapeTransformer();
	Layout<V, E> layout = viewer.getGraphLayout();
	Function<V, Rectangle> transformer = v -> {

		Shape s = shapeTransformer.apply(v);
		Rectangle bounds = s.getBounds();
		Point2D p = layout.apply(v);

		// Note: we use the raw x/y of the layout; the view code will center the vertices
		bounds.setLocation(new Point((int) p.getX(), (int) p.getY()));
		return bounds;
	};
	return transformer;
}
 

protected final void handleRequest(MessageReceivedEvent event, SubsystemContext<M> context) {
   PlatformMessage request = event.getMessage();
   String type = request.getMessageType();
   Function<SubsystemEventAndContext, MessageBody> handler = requestHandlers.get(type);
   if(handler == null) {
      context.sendResponse(request, Errors.invalidRequest(type));
   }
   else {
      MessageBody response;
      try {
         response = handler.apply(new SubsystemEventAndContext(context, event));
      }
      catch(Exception e) {
         context.logger().warn("Error handling request {}", request, e);
         response = Errors.fromException(e);
      }
      if(response != null) {
         context.sendResponse(request, response);
      }
   }
}
 

public static <K, V> Map<K, V> toUnmodifiableMap(Collection<V> elements, Function<V, K> keyFunction) {
 if(elements == null || elements.isEmpty()) {
 	return Collections.emptyMap();
 }
 Map<K, V> map = new HashMap<>(elements.size());
 for(V element: elements) {
 	K key = keyFunction.apply(element);
 	if(key != null) {
 		map.put(key, element);
 	}
 }
 return Collections.unmodifiableMap(map);
}
 

private static void processOutput(InputStream inputStream, Function<String, Void> function) throws IOException {
    try (BufferedReader reader = new BufferedReader(new InputStreamReader(inputStream))) {
        String line = null;
        while ((line = reader.readLine()) != null) {
            function.apply(line);
        }
    }
}
 

public <T> int batchUpdate(String sql, List<T> entities, Function<T, Object[]> function) {
    int result = 0;
    List<Object[]> paramList = Lists.newLinkedList();
    for (T entity : entities) {
        Object[] params = function.apply(entity);
        paramList.add(params);
    }
    for (JdbcTemplate jdbcTemplate : jdbcTemplates.values()) {
        int[] resultArray = jdbcTemplate.batchUpdate(sql, paramList);
        for (int count : resultArray) {
            result += count;
        }
    }
    return result;
}
 

/**
 * 将列表转化为指定map对象
 *
 * @param list          列表
 * @param functionKey   key转化函数
 * @param functionValue
 * @param <S>           列表元素类型
 * @param <T>           mapping key
 * @return map 对象
 */
public static <S, T, U> Map<S, T> transformToMap(List<U> list, Function<U, S> functionKey, Function<U, T> functionValue) {
    if (org.apache.commons.collections4.CollectionUtils.isEmpty(list)) {
        return Maps.newHashMapWithExpectedSize(0);
    }

    Map<S, T> map = Maps.newHashMap();
    for (U element : list) {
        if (functionValue.apply(element) != null) {
            map.put(functionKey.apply(element), functionValue.apply(element));
        }
    }
    return map;
}
 

public static <T extends Comparable, E extends Comparable> Iterator<T> extractAndSort(Iterator<T> input, Function<T, E> extractor) {
    TreeMultimap<E, T> reorgnized = TreeMultimap.create();
    while (input.hasNext()) {
        T t = input.next();
        E e = extractor.apply(t);
        reorgnized.put(e, t);
    }
    return reorgnized.values().iterator();
}
 

public void ensureVertexVisible(V vertex, Rectangle area) {

		RenderContext<V, E> renderContext = primaryViewer.getRenderContext();
		Function<? super V, Shape> transformer = renderContext.getVertexShapeTransformer();
		Shape shape = transformer.apply(vertex);
		Rectangle bounds = shape.getBounds();
		ensureVertexAreaVisible(vertex, bounds, null);
	}
 

public static <K, V> Map<K, V> toUnmodifiableMap(V[] elements, Function<V, K> keyFunction) {
   if(elements == null || elements.length == 0) {
      return Collections.emptyMap();
   }
   Map<K, V> map = new HashMap<>(elements.length);
   for(V element: elements) {
      K key = keyFunction.apply(element);
      if(key != null) {
         map.put(key, element);
      }
   }
   return Collections.unmodifiableMap(map);
}
 

public static <I> boolean anyTrue(List<I> inputList, Function<I, Boolean> test) {
   if (inputList == null || inputList.isEmpty()) {
      return false;
   }
   for (I input : inputList) {
      if (test.apply(input)) {
         return true;
      }
   }
   return false;
}
 

private void doNotify(List<String> serverUrls, String uri, String type, Function<String, Request> requestBuilder) {
    List<ListenableFuture<Response>> futures = Lists.newArrayListWithCapacity(serverUrls.size());
    for (String oneServer : serverUrls) {
        String url = "http://" + oneServer + "/" + uri;
        Request request = requestBuilder.apply(url);
        ListenableFuture<Response> future = HttpListenableFuture.wrap(httpClient.executeRequest(request));
        futures.add(future);
    }

    dealResult(futures, serverUrls, type);
}
 

@SuppressWarnings({ "rawtypes", "unchecked" })
private static <V> Shape getVertexShapeForEdge(V v, Function<? super V, Shape> vertexShaper) {
	if (vertexShaper instanceof VisualGraphVertexShapeTransformer) {
		if (v instanceof VisualVertex) {
			VisualVertex vv = (VisualVertex) v;

			// Note: it is a bit odd that we 'know' to use the compact shape here for 
			// 		 hit detection, but this is how the edge is painted, so we want the 
			//       view to match the mouse.
			return ((VisualGraphVertexShapeTransformer) vertexShaper).transformToCompactShape(
				vv);
		}
	}
	return vertexShaper.apply(v);
}
 

private <R> Consumer<PlatformMessage> wrapConsumer(Object ths, Method m, Predicate<Address> p, ArgumentResolverFactory<PlatformMessage, ?> resolver) {
   ArgumentResolverFactory<PlatformMessage, ?> factory =
         this.resolver == null ?
               resolver :
               Resolvers.chain(resolver, (ArgumentResolverFactory) this.resolver);
   Function<PlatformMessage, ?> h = 
         Methods
            .buildInvokerFactory(factory)
            .build()
            .wrapWithThis(m, ths);
   return (message) -> { if(p.apply(message.getSource())) { h.apply(message); } };
}
 

public static <T> void forEach(List<T> list, Function<T, Void> function) {
    for (T t : list) {
        function.apply(t);
    }
}
 

public <T> State<T> transform(Function<V,T> transformer) {
   return new State<T>(type, transformer.apply(value));
}