Reflection.java revision 11b67b201adb173d5f6f1b7a3fd337fda91e200f 
1/*
2 * Copyright (C) 2017 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *      http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17import java.lang.reflect.Constructor;
18import java.lang.reflect.Field;
19import java.lang.reflect.Method;
20import java.lang.reflect.Modifier;
21import java.util.Arrays;
22
23public class Reflection {
24  public static boolean canDiscoverWithGetDeclaredField(Class<?> klass, String name) {
25    try {
26      klass.getDeclaredField(name);
27      return true;
28    } catch (NoSuchFieldException ex) {
29      return false;
30    }
31  }
32
33  public static boolean canDiscoverWithGetDeclaredFields(Class<?> klass, String name) {
34    for (Field f : klass.getDeclaredFields()) {
35      if (f.getName().equals(name)) {
36        return true;
37      }
38    }
39    return false;
40  }
41
42  public static boolean canDiscoverWithGetField(Class<?> klass, String name) {
43    try {
44      klass.getField(name);
45      return true;
46    } catch (NoSuchFieldException ex) {
47      return false;
48    }
49  }
50
51  public static boolean canDiscoverWithGetFields(Class<?> klass, String name) {
52    for (Field f : klass.getFields()) {
53      if (f.getName().equals(name)) {
54        return true;
55      }
56    }
57    return false;
58  }
59
60  public static boolean canGetField(Class<?> klass, String name) {
61    try {
62      Field f = klass.getDeclaredField(name);
63      f.setAccessible(true);
64      f.getInt(Modifier.isStatic(f.getModifiers()) ? null : klass.newInstance());
65      return true;
66    } catch (Exception ex) {
67      ex.printStackTrace();
68      return false;
69    }
70  }
71
72  public static boolean canSetField(Class<?> klass, String name) {
73    try {
74      Field f = klass.getDeclaredField(name);
75      f.setAccessible(true);
76      f.setInt(Modifier.isStatic(f.getModifiers()) ? null : klass.newInstance(), 42);
77      return true;
78    } catch (Exception ex) {
79      ex.printStackTrace();
80      return false;
81    }
82  }
83
84  public static boolean canDiscoverWithGetDeclaredMethod(Class<?> klass, String name) {
85    try {
86      klass.getDeclaredMethod(name);
87      return true;
88    } catch (NoSuchMethodException ex) {
89      return false;
90    }
91  }
92
93  public static boolean canDiscoverWithGetDeclaredMethods(Class<?> klass, String name) {
94    for (Method m : klass.getDeclaredMethods()) {
95      if (m.getName().equals(name)) {
96        return true;
97      }
98    }
99    return false;
100  }
101
102  public static boolean canDiscoverWithGetMethod(Class<?> klass, String name) {
103    try {
104      klass.getMethod(name);
105      return true;
106    } catch (NoSuchMethodException ex) {
107      return false;
108    }
109  }
110
111  public static boolean canDiscoverWithGetMethods(Class<?> klass, String name) {
112    for (Method m : klass.getMethods()) {
113      if (m.getName().equals(name)) {
114        return true;
115      }
116    }
117    return false;
118  }
119
120  public static boolean canInvokeMethod(Class<?> klass, String name) {
121    try {
122      Method m = klass.getDeclaredMethod(name);
123      m.setAccessible(true);
124      m.invoke(klass.isInterface() ? null : klass.newInstance());
125      return true;
126    } catch (Exception ex) {
127      ex.printStackTrace();
128      return false;
129    }
130  }
131
132  public static boolean canDiscoverWithGetDeclaredConstructor(Class<?> klass, Class<?> args[]) {
133    try {
134      klass.getDeclaredConstructor(args);
135      return true;
136    } catch (NoSuchMethodException ex) {
137      return false;
138    }
139  }
140
141  public static boolean canDiscoverWithGetDeclaredConstructors(Class<?> klass, Class<?> args[]) {
142    for (Constructor c : klass.getDeclaredConstructors()) {
143      if (Arrays.equals(c.getParameterTypes(), args)) {
144        return true;
145      }
146    }
147    return false;
148  }
149
150  public static boolean canDiscoverWithGetConstructor(Class<?> klass, Class<?> args[]) {
151    try {
152      klass.getConstructor(args);
153      return true;
154    } catch (NoSuchMethodException ex) {
155      return false;
156    }
157  }
158
159  public static boolean canDiscoverWithGetConstructors(Class<?> klass, Class<?> args[]) {
160    for (Constructor c : klass.getConstructors()) {
161      if (Arrays.equals(c.getParameterTypes(), args)) {
162        return true;
163      }
164    }
165    return false;
166  }
167
168  public static boolean canInvokeConstructor(Class<?> klass, Class<?> args[], Object[] initargs) {
169    try {
170      Constructor c = klass.getDeclaredConstructor(args);
171      c.setAccessible(true);
172      c.newInstance(initargs);
173      return true;
174    } catch (Exception ex) {
175      ex.printStackTrace();
176      return false;
177    }
178  }
179
180  public static boolean canUseNewInstance(Class<?> klass) throws IllegalAccessException {
181    try {
182      klass.newInstance();
183      return true;
184    } catch (InstantiationException ex) {
185      return false;
186    }
187  }
188
189  private static native int getHiddenApiAccessFlags();
190
191  public static boolean canObserveFieldHiddenAccessFlags(Class<?> klass, String name)
192      throws Exception {
193    return (klass.getDeclaredField(name).getModifiers() & getHiddenApiAccessFlags()) != 0;
194  }
195
196  public static boolean canObserveMethodHiddenAccessFlags(Class<?> klass, String name)
197      throws Exception {
198    return (klass.getDeclaredMethod(name).getModifiers() & getHiddenApiAccessFlags()) != 0;
199  }
200
201  public static boolean canObserveConstructorHiddenAccessFlags(Class<?> klass, Class<?> args[])
202      throws Exception {
203    return (klass.getConstructor(args).getModifiers() & getHiddenApiAccessFlags()) != 0;
204  }
205}
206