Classes in this File | Line Coverage | Branch Coverage | Complexity | ||||
ConstructorHelper |
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| 4.666666666666667;4.667 |
1 | package org.apache.ojb.broker.util; | |
2 | ||
3 | /* Copyright 2003-2005 The Apache Software Foundation | |
4 | * | |
5 | * Licensed under the Apache License, Version 2.0 (the "License"); | |
6 | * you may not use this file except in compliance with the License. | |
7 | * You may obtain a copy of the License at | |
8 | * | |
9 | * http://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 | import java.lang.reflect.Constructor; | |
19 | ||
20 | import org.apache.ojb.broker.metadata.ClassNotPersistenceCapableException; | |
21 | ||
22 | /** | |
23 | * This class helps us to construct new instances. | |
24 | * We don't want to rely on public default constructors and | |
25 | * have to try hard to also use private or protected constructors. | |
26 | * | |
27 | * @author Thomas Mahler | |
28 | * @author Lance Eason | |
29 | * | |
30 | * @version $Id: ConstructorHelper.java,v 1.1 2007-08-24 22:17:36 ewestfal Exp $ | |
31 | */ | |
32 | public class ConstructorHelper | |
33 | { | |
34 | /** | |
35 | * represents a zero sized parameter array | |
36 | */ | |
37 | private static final Object[] NO_ARGS = {}; | |
38 | ||
39 | /** | |
40 | * no public constructor, please use the static method only. | |
41 | */ | |
42 | private ConstructorHelper() | |
43 | { | |
44 | } | |
45 | ||
46 | /** | |
47 | * create a new instance of class clazz. | |
48 | * first use the public default constructor. | |
49 | * If this fails also try to use protected an private constructors. | |
50 | * @param clazz the class to instantiate | |
51 | * @return the fresh instance of class clazz | |
52 | * @throws InstantiationException | |
53 | */ | |
54 | public static Object instantiate(Class clazz) throws InstantiationException | |
55 | { | |
56 | Object result = null; | |
57 | try | |
58 | { | |
59 | result = ClassHelper.newInstance(clazz); | |
60 | } | |
61 | catch(IllegalAccessException e) | |
62 | { | |
63 | try | |
64 | { | |
65 | result = ClassHelper.newInstance(clazz, true); | |
66 | } | |
67 | catch(Exception e1) | |
68 | { | |
69 | throw new ClassNotPersistenceCapableException("Can't instantiate class '" | |
70 | + (clazz != null ? clazz.getName() : "null") | |
71 | + "', message was: " + e1.getMessage() + ")", e1); | |
72 | } | |
73 | } | |
74 | return result; | |
75 | } | |
76 | ||
77 | /** | |
78 | * create a new instance of the class represented by the no-argument constructor provided | |
79 | * @param constructor the zero argument constructor for the class | |
80 | * @return a new instance of the class | |
81 | * @throws InstantiationException | |
82 | * @throws ClassNotPersistenceCapableException if the constructor is null or there is an | |
83 | * exception while trying to create a new instance | |
84 | */ | |
85 | public static Object instantiate(Constructor constructor) throws InstantiationException | |
86 | { | |
87 | if(constructor == null) | |
88 | { | |
89 | throw new ClassNotPersistenceCapableException( | |
90 | "A zero argument constructor was not provided!"); | |
91 | } | |
92 | ||
93 | Object result = null; | |
94 | try | |
95 | { | |
96 | result = constructor.newInstance(NO_ARGS); | |
97 | } | |
98 | catch(InstantiationException e) | |
99 | { | |
100 | throw e; | |
101 | } | |
102 | catch(Exception e) | |
103 | { | |
104 | throw new ClassNotPersistenceCapableException("Can't instantiate class '" | |
105 | + (constructor != null ? constructor.getDeclaringClass().getName() : "null") | |
106 | + "' with given constructor: " + e.getMessage(), e); | |
107 | } | |
108 | return result; | |
109 | } | |
110 | } |