gwt - Requestfactory 克隆代理到新上下文

Question

我正面临 gwt 问题 5794:http://code.google.com/p/google-web-toolkit/issues/detail?id=5794

我看到有一个 8 个月大的补丁，但它还没有包含在 gwt 2.5 RC1 中 http://gwt-code-reviews.appspot.com/1620804/

有谁知道这个补丁是否会包含在 gwt 2.5 rc2 或最终版本中？

如果没有，有人可以向我解释什么是该问题的最佳解决方法。

提前致谢。

Answer 1

我从 AbstractRequestContext 的 copyBeanAndCollections 方法中想到了这个。它似乎完成了我想要使用新上下文将代理克隆到另一个代理的工作。这本质上要求您首先创建一个新代理或使用新上下文编辑代理，但我不再需要使用复制构造函数将属性迭代复制到新代理。我仍在测试，但我创建了一个简单的 GWTTestCase，它似乎可以正常工作。

快速更新

我解决了请求工厂实体定位器无法解析类型的问题，因此我重新添加了 stableid 和版本标签以进行克隆。这可能是个坏主意，当我弄清楚稳定 id 是否用于原始对象的实际引用的类类型时，我会更新。我的猜测是它用于在服务器端解析类型。

public class ProxyUtils {

    public static <T extends BaseProxy> AutoBean<T> cloneBeanProperties(final T original, final T clone, final RequestContext toContext) {

        AutoBean<T> originalBean = AutoBeanUtils.getAutoBean(original);
        AutoBean<T> cloneBean = AutoBeanUtils.getAutoBean(clone);

        return cloneBeanProperties(originalBean, cloneBean, toContext);
    }

    /**
     * Shallow-clones an autobean and makes duplicates of the collection types.
     * A regular {@link AutoBean#clone} won't duplicate reference properties.
     */
    public static <T extends BaseProxy> AutoBean<T> cloneBeanProperties(final AutoBean<T> toClone, final AutoBean<T> clone, final RequestContext toContext) {
        // NOTE: This may be a bad idea, i don't know if the STABLE_ID is the type or if it is the
        // actual server side reference to this object. Don't want it to update my original object.
        // I added this back in because I was getting an InstantionException in the locator I am
        // pretty sure this is because request factory server side could not resolve the class type. 
        // Maybe someone could shed some light on this one, if you know what the stable id is really
        // used for. 
        clone.setTag(STABLE_ID, toClone.getTag(STABLE_ID));
        clone.setTag(Constants.VERSION_PROPERTY_B64, toClone.getTag(Constants.VERSION_PROPERTY_B64));
        clone.accept(new AutoBeanVisitor() {
            final Map<String, Object> values = AutoBeanUtils.getAllProperties(toClone);

            @Override
            public boolean visitCollectionProperty(String propertyName, AutoBean<Collection<?>> value, CollectionPropertyContext ctx) {
                // javac generics bug
                value = AutoBeanUtils.<Collection<?>, Collection<?>> getAutoBean((Collection<?>) values.get(propertyName));
                if (value != null) {
                    Collection<Object> collection;
                    if (List.class == ctx.getType()) {
                        collection = new ArrayList<Object>();
                    } else if (Set.class == ctx.getType()) {
                        collection = new HashSet<Object>();
                    } else {
                        // Should not get here if the validator works correctly
                        throw new IllegalArgumentException(ctx.getType().getName());
                    }

                    if (isValueType(ctx.getElementType()) || isEntityType(ctx.getElementType())) {
                        /*
                         * Proxies must be edited up-front so that the elements
                         * in the collection have stable identity.
                         */
                        for (Object o : value.as()) {
                            if (o == null) {
                                collection.add(null);
                            } else {
                                collection.add(editProxy(toContext, (Class<T>) ctx.getType(), (T) o));
                            }
                        }
                    } else {
                        // For simple values, just copy the values
                        collection.addAll(value.as());
                    }

                    ctx.set(collection);
                }
                return false;
            }

            @Override
            public boolean visitReferenceProperty(String propertyName, AutoBean<?> value, PropertyContext ctx) {
                value = AutoBeanUtils.getAutoBean(values.get(propertyName));
                if (value != null) {
                    if (isValueType(ctx.getType()) || isEntityType(ctx.getType())) {
                        /*
                         * Value proxies must be cloned upfront, since the value
                         * is replaced outright.
                         */
                        @SuppressWarnings("unchecked")
                        AutoBean<BaseProxy> valueBean = (AutoBean<BaseProxy>) value;
                        ctx.set(editProxy(toContext, (Class<T>) ctx.getType(), (T) valueBean.as()));
                    } else {
                        ctx.set(value.as());
                    }
                }
                return false;
            }

            @Override
            public boolean visitValueProperty(String propertyName, Object value, PropertyContext ctx) {
                ctx.set(values.get(propertyName));
                return false;
            }
        });
        return clone;
    }



    /**
     * Take ownership of a proxy instance and make it editable.
     */
    private static <T extends BaseProxy> T editProxy(RequestContext ctx, Class<T> clazz, T object) {
        AutoBean<T> toClone = AutoBeanUtils.getAutoBean(object);

        // Create editable copies
        AutoBean<T> parent = toClone;

        AutoBean<T> clone = (AutoBean<T>) ctx.create(clazz);
        AutoBean<T> cloned = cloneBeanProperties(toClone, clone, ctx);

        cloned.setTag(Constants.PARENT_OBJECT, parent);
        return cloned.as();
    }


    private static boolean isEntityType(Class<?> clazz) {
        return isAssignableTo(clazz, EntityProxy.class);
    }

    private static boolean isValueType(Class<?> clazz) {
        return isAssignableTo(clazz, ValueProxy.class);
    }

    public static boolean isAssignableTo(Class<?> thisClass, Class<?> assignableTo ) {
        if(thisClass == null || assignableTo == null) {
          return false;
        }

        if(thisClass.equals(assignableTo)) {
            return true;
        }

        Class<?> currentSuperClass = thisClass.getSuperclass();
        while(currentSuperClass != null) {
            if(currentSuperClass.equals(assignableTo)) {
                return true;
            }
            currentSuperClass = thisClass.getSuperclass();
        }
        return false;
    }
}

这是我成功完成的简单单元测试。我确实有一些错误，我必须在 isAssignableFrom 方法中进行调查。

   public void testCloneProxy() {
        DaoRequestFactory requestFactory = GWT.create(DaoRequestFactory.class);
        RequestContext fromContext = requestFactory.analyticsTaskRequest();

        AnalyticsOperationInputProxy from = fromContext.create(AnalyticsOperationInputProxy.class);

        from.setDisplayName("DISPLAY 1");
        from.setInputName("INPUT 1");


        RequestContext toContext = requestFactory.analyticsTaskRequest();

        AnalyticsOperationInputProxy to = toContext.create(AnalyticsOperationInputProxy.class);


        ProxyUtils.cloneBeanProperties(from, to, toContext);

        System.out.println("Cloned output " + to.getDisplayName());
        System.out.println("Cloned output " + to.getInputName());

        Assert.assertTrue("Display name not equal" , from.getDisplayName().equals(to.getDisplayName()));
        Assert.assertTrue("Input name not equal" , from.getInputName().equals(to.getInputName()));

    }