1 /*
2 * Licensed to the Apache Software Foundation (ASF) under one or more
3 * contributor license agreements. See the NOTICE file distributed with
4 * this work for additional information regarding copyright ownership.
5 * The ASF licenses this file to You under the Apache License, Version 2.0
6 * (the "License"); you may not use this file except in compliance with
7 * the License. You may obtain a copy of the License at
8 *
9 * https://www.apache.org/licenses/LICENSE-2.0
10 *
11 * Unless required by applicable law or agreed to in writing, software
12 * distributed under the License is distributed on an "AS IS" BASIS,
13 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 * See the License for the specific language governing permissions and
15 * limitations under the License.
16 */
17
18 package org.apache.commons.jexl3.introspection;
19 import org.apache.commons.jexl3.JexlException;
20
21 /**
22 * Interface used for regular method invocation.
23 * Ex.
24 * <code>
25 * ${foo.bar()}
26 * </code>
27 *
28 * @since 1.0
29 */
30 public interface JexlMethod {
31
32 /**
33 * returns the return type of the method invoked.
34 *
35 * @return return type
36 */
37 Class<?> getReturnType();
38
39 /**
40 * Invocation method, called when the method invocation should be performed
41 * and a value returned.
42
43 * @param obj the object
44 * @param params method parameters.
45 * @return the result
46 * @throws Exception on any error.
47 */
48 Object invoke(Object obj, Object... params) throws Exception;
49
50 /**
51 * Specifies if this JexlMethod is cacheable and able to be reused for this
52 * class of object it was returned for.
53 *
54 * @return true if can be reused for this class, false if not
55 */
56 boolean isCacheable();
57
58 /**
59 * Checks whether a tryInvoke return value indicates a failure or not.
60 * <p>Usage is : <code>Object r = tryInvoke(...); if (tryFailed(r) {...} else {...}</code>
61 *
62 * @param rval the value returned by tryInvoke
63 * @return true if tryInvoke failed, false otherwise
64 */
65 boolean tryFailed(Object rval);
66
67 /**
68 * Attempts to reuse this JexlMethod, checking that it is compatible with
69 * the actual set of arguments.
70 * Related to isCacheable since this method is often used with cached JexlMethod instances.
71 *
72 * @param name the method name
73 * @param obj the object to invoke the method upon
74 * @param params the method arguments
75 * @return the result of the method invocation that should be checked by tryFailed to determine if it succeeded
76 * or failed.
77 * @throws JexlException.TryFailed if the underlying method was invoked but threw an exception
78 * ({@link java.lang.reflect.InvocationTargetException})
79 */
80 Object tryInvoke(String name, Object obj, Object... params) throws JexlException.TryFailed;
81 }