| /* |
| * Copyright 2008 Google Inc. |
| * |
| * Licensed under the Apache License, Version 2.0 (the "License"); you may not |
| * use this file except in compliance with the License. You may obtain a copy of |
| * the License at |
| * |
| * http://www.apache.org/licenses/LICENSE-2.0 |
| * |
| * Unless required by applicable law or agreed to in writing, software |
| * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT |
| * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the |
| * License for the specific language governing permissions and limitations under |
| * the License. |
| */ |
| package com.google.gwt.dev.shell; |
| |
| import com.google.gwt.dev.shell.JsValue.DispatchMethod; |
| |
| import java.lang.reflect.InvocationTargetException; |
| |
| /** |
| * Wraps an arbitrary Java Method as a Dispatchable component. The class was |
| * motivated by the need to expose Java objects into JavaScript. |
| */ |
| class MethodDispatch implements DispatchMethod { |
| |
| private final CompilingClassLoader classLoader; |
| |
| private final MethodAdaptor method; |
| |
| public MethodDispatch(CompilingClassLoader classLoader, MethodAdaptor method) { |
| this.classLoader = classLoader; |
| this.method = method; |
| } |
| |
| /** |
| * Invoke a Java method from JavaScript. This is called solely from native |
| * code. |
| * |
| * @param jsthis JavaScript reference to Java object |
| * @param jsargs array of JavaScript values for parameters |
| * @param returnValue JavaScript value to return result in |
| * @return <code>true</code> if an exception was thrown |
| * @throws RuntimeException if improper arguments are supplied |
| */ |
| @Override |
| public boolean invoke(JsValue jsthis, JsValue[] jsargs, JsValue returnValue) { |
| Class<?>[] paramTypes = method.getParameterTypes(); |
| int argc = paramTypes.length; |
| Object args[] = new Object[argc]; |
| // too many arguments are ok: the extra will be silently ignored |
| if (jsargs.length < argc) { |
| throw new RuntimeException("Not enough arguments to " + method); |
| } |
| Object jthis = null; |
| if (method.needsThis()) { |
| jthis = JsValueGlue.get(jsthis, classLoader, method.getDeclaringClass(), |
| "invoke this"); |
| if (jthis == null) { |
| throw ModuleSpace.createJavaScriptException(classLoader, |
| "Invoking an instance method on a null instance"); |
| } |
| } |
| for (int i = 0; i < argc; ++i) { |
| args[i] = JsValueGlue.get(jsargs[i], classLoader, paramTypes[i], |
| "invoke arguments"); |
| } |
| try { |
| Object result; |
| try { |
| result = method.invoke(jthis, args); |
| } catch (IllegalAccessException e) { |
| // should never, ever happen |
| e.printStackTrace(); |
| throw new RuntimeException(e); |
| } |
| JsValueGlue.set(returnValue, classLoader, method.getReturnType(), result); |
| return false; |
| } catch (InstantiationException e) { |
| // If we get here, it means an exception is being thrown from |
| // Java back into JavaScript |
| wrapException(returnValue, e.getCause()); |
| return true; |
| |
| } catch (InvocationTargetException e) { |
| // If we get here, it means an exception is being thrown from |
| // Java back into JavaScript |
| wrapException(returnValue, e.getTargetException()); |
| return true; |
| |
| } catch (IllegalArgumentException e) { |
| // TODO(jat): log to treelogger instead? If so, how do I get to it? |
| System.err.println("MethodDispatch.invoke, method=" + method.toString() |
| + ": argument mismatch"); |
| for (int i = 0; i < argc; ++i) { |
| System.err.println(" param " + i + " type is " |
| + paramTypes[i].toString() + " value is type " |
| + jsargs[i].getTypeString() + " = " + args[i].toString()); |
| } |
| throw e; |
| } |
| } |
| |
| @Override |
| public String toString() { |
| return method.toString(); |
| } |
| |
| /** |
| * Send an exception back to the client. This will either wrap a Java |
| * Throwable as a Java Object to be sent over the wire, or if the exception is |
| * a JavaScriptException unwinding through the stack, send the original thrown |
| * object instead. |
| */ |
| private void wrapException(JsValue returnValue, Throwable t) { |
| ModuleSpace.setThrownJavaException(t); |
| |
| Object thrown = ModuleSpace.getThrownObject(classLoader, t); |
| Class<?> type = thrown == null ? Object.class : thrown.getClass(); |
| JsValueGlue.set(returnValue, classLoader, type, thrown); |
| } |
| } |