| 1 | // Copyright 2004-2007 Jean-Francois Poilpret |
| 2 | // |
| 3 | // Licensed under the Apache License, Version 2.0 (the "License"); |
| 4 | // you may not use this file except in compliance with the License. |
| 5 | // You may obtain a copy of the License at |
| 6 | // |
| 7 | // http://www.apache.org/licenses/LICENSE-2.0 |
| 8 | // |
| 9 | // Unless required by applicable law or agreed to in writing, software |
| 10 | // distributed under the License is distributed on an "AS IS" BASIS, |
| 11 | // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. |
| 12 | // See the License for the specific language governing permissions and |
| 13 | // limitations under the License. |
| 14 | |
| 15 | package net.sourceforge.hiveutils.service.impl; |
| 16 | |
| 17 | import java.lang.reflect.InvocationHandler; |
| 18 | import java.lang.reflect.InvocationTargetException; |
| 19 | import java.lang.reflect.Method; |
| 20 | import java.lang.reflect.Proxy; |
| 21 | import java.util.Map; |
| 22 | |
| 23 | import net.sourceforge.hiveutils.service.ExceptionMapper; |
| 24 | |
| 25 | /** |
| 26 | * Utility class to create a proxy object around a service implementation, in |
| 27 | * order to catch any exception thrown by the implementation and throw |
| 28 | * another exception, according to application developer-supplied rules. |
| 29 | * <p> |
| 30 | * As a matter of fact, such proxy creation also enables to make a POJO service |
| 31 | * implementation with no service interface usable by Hivemind, by just creating |
| 32 | * an interface with all public methods of the POJO. |
| 33 | * |
| 34 | * @author Jean-Francois Poilpret |
| 35 | */ |
| 36 | final public class AdapterProxyFactoryHelper |
| 37 | { |
| 38 | private AdapterProxyFactoryHelper() |
| 39 | { |
| 40 | } |
| 41 | |
| 42 | /** |
| 43 | * Creates a proxy of type <code>serviceInterface</code>, wrapping |
| 44 | * <code>service</code> implementation class, and translating any |
| 45 | * exception thrown by <code>service</code> into another exception through |
| 46 | * <code>mapper</code>. |
| 47 | * |
| 48 | * @param serviceInterface the interface that the proxy must implement; |
| 49 | * <code>service</code> does not have to implement that interface or any |
| 50 | * interface at all. |
| 51 | * @param service the actual service implementation class to be proxied |
| 52 | * @param methodsMapping a map from <code>serviceInterface</code> methods to |
| 53 | * <code>service</code> methods to be used to perform the method mapping |
| 54 | * from one class to the other |
| 55 | * @param exceptionMapper the instance to perform the mappping of any thrown |
| 56 | * <code>Throwable</code> into another one. |
| 57 | * @return the proxied service that implements <code>serviceInterface</code> |
| 58 | * and delegates calls to <code>service</code> |
| 59 | */ |
| 60 | static public Object createProxy(Class serviceInterface, |
| 61 | Object service, |
| 62 | Map methodsMapping, |
| 63 | ExceptionMapper exceptionMapper) |
| 64 | { |
| 65 | // Create Dynamic proxy |
| 66 | return Proxy.newProxyInstance( serviceInterface.getClassLoader(), |
| 67 | new Class[] {serviceInterface}, |
| 68 | new Bridge(service, exceptionMapper, methodsMapping)); |
| 69 | } |
| 70 | |
| 71 | static private class Bridge implements InvocationHandler |
| 72 | { |
| 73 | public Bridge(Object service, ExceptionMapper mapper, Map methods) |
| 74 | { |
| 75 | _service = service; |
| 76 | _mapper = mapper; |
| 77 | _methods = methods; |
| 78 | } |
| 79 | |
| 80 | //CSOFF: IllegalThrowsCheck |
| 81 | //CSOFF: IllegalCatchCheck |
| 82 | public Object invoke(Object proxy, Method method, Object[] args) |
| 83 | throws Throwable |
| 84 | { |
| 85 | // Find method to invoke on service |
| 86 | Method realMethod = (Method) _methods.get(method); |
| 87 | try |
| 88 | { |
| 89 | return realMethod.invoke(_service, args); |
| 90 | } |
| 91 | catch (InvocationTargetException e) |
| 92 | { |
| 93 | throw _mapper.translate(e.getTargetException()); |
| 94 | } |
| 95 | catch (Throwable t) |
| 96 | { |
| 97 | throw _mapper.translate(t); |
| 98 | } |
| 99 | } |
| 100 | //CSON: IllegalCatchCheck |
| 101 | //CSON: IllegalThrowsCheck |
| 102 | |
| 103 | private final Object _service; |
| 104 | private final ExceptionMapper _mapper; |
| 105 | private final Map _methods; |
| 106 | } |
| 107 | } |