import com.google.gwt.resources.client.ResourceCallback; //导入依赖的package包/类
/**
 * Creates a fake resource class that returns its own name where possible.
 */
@SuppressWarnings("unchecked") // safe since the proxy implements type
private <T> T createFakeResource(Class<T> type, final String name) {
  return (T) Proxy.newProxyInstance(
      FakeClientBundleProvider.class.getClassLoader(),
      new Class<?>[] {type},
      new InvocationHandler() {
        @Override
        public Object invoke(Object proxy, Method method, Object[] args) throws Exception {
          Class<?> returnType = method.getReturnType();
          if (returnType == String.class) {
            return name;
          } else if (returnType == SafeHtml.class) {
            return SafeHtmlUtils.fromTrustedString(name);
          } else if (returnType == SafeUri.class) {
            return UriUtils.fromTrustedString(name);
          } else if (returnType == boolean.class) {
            return false;
          } else if (returnType == int.class) {
            return 0;
          } else if (method.getParameterTypes()[0] == ResourceCallback.class) {
            // Read the underlying resource type out of the generic parameter
            // in the method's argument
            Class<?> resourceType = 
                (Class<?>) 
                ((ParameterizedType) args[0].getClass().getGenericInterfaces()[0])
                .getActualTypeArguments()[0];
            ((ResourceCallback<ResourcePrototype>) args[0]).onSuccess(
                (ResourcePrototype) createFakeResource(resourceType, name));
            return null;
          } else {
            throw new IllegalArgumentException(
                "Unexpected return type for method " + method.getName());
          }
        }
      });
}
 

import com.google.gwt.resources.client.ResourceCallback; //导入依赖的package包/类
@Test
public void shouldMockClientBundles() throws Exception {
  SomeClientBundle clientBundle = GWT.create(SomeClientBundle.class);

  // CSS resources should be faked
  assertEquals("style1", clientBundle.css().style1());

  // Other internal resources should return their names from getSafeUri or getText
  assertEquals("data", clientBundle.data().getSafeUri().asString());
  assertEquals(0, clientBundle.image().getHeight());
  assertEquals(0, clientBundle.image().getLeft());
  assertEquals("image", clientBundle.image().getSafeUri().asString());
  assertEquals(0, clientBundle.image().getTop());
  assertEquals(0, clientBundle.image().getWidth());
  assertEquals(false, clientBundle.image().isAnimated());
  assertEquals("text", clientBundle.text().getText());

  // External resources should return their name in a callback
  final StringBuilder result = new StringBuilder();
  clientBundle.externalText().getText(new ResourceCallback<TextResource>() {
    @Override
    public void onSuccess(TextResource resource) {
      result.append(resource.getText());
    }
    @Override
    public void onError(ResourceException e) {
      throw new RuntimeException(e);
    }
  });
  assertEquals("externalText", result.toString());
}