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1   /*
2    * Licensed to the Apache Software Foundation (ASF) under one
3    * or more contributor license agreements.  See the NOTICE file
4    * distributed with this work for additional information
5    * regarding copyright ownership.  The ASF licenses this file
6    * to you under the Apache License, Version 2.0 (the
7    * "License"); you may not use this file except in compliance
8    * with the License.  You may obtain a copy of the License at
9    *
10   *     http://www.apache.org/licenses/LICENSE-2.0
11   *
12   * Unless required by applicable law or agreed to in writing,
13   * software distributed under the License is distributed on an
14   * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
15   * KIND, either express or implied.  See the License for the
16   * specific language governing permissions and limitations
17   * under the License.
18   */
19  package org.apache.shiro.guice.web;
20  
21  import java.lang.reflect.Constructor;
22  import java.util.Collections;
23  import java.util.HashSet;
24  import java.util.Set;
25  
26  import com.google.inject.Inject;
27  import com.google.inject.Injector;
28  import com.google.inject.Key;
29  import com.google.inject.ProvisionException;
30  import com.google.inject.spi.Dependency;
31  import com.google.inject.spi.InjectionPoint;
32  import com.google.inject.spi.ProviderWithDependencies;
33  
34  class AbstractInjectionProvider<T> implements ProviderWithDependencies<T> {
35      private Key<T> key;
36  
37      @Inject
38      Injector injector;
39  
40      private InjectionPoint constructorInjectionPoint;
41      private Set<Dependency<?>> dependencies;
42  
43      public AbstractInjectionProvider(Key<T> key) {
44          this.key = key;
45          constructorInjectionPoint = InjectionPoint.forConstructorOf(key.getTypeLiteral());
46  
47          Set<Dependency<?>> dependencyBuilder = new HashSet<Dependency<?>>();
48          dependencyBuilder.addAll(constructorInjectionPoint.getDependencies());
49          for (InjectionPoint injectionPoint : InjectionPoint.forInstanceMethodsAndFields(key.getTypeLiteral())) {
50              dependencyBuilder.addAll(injectionPoint.getDependencies());
51          }
52          this.dependencies = Collections.unmodifiableSet(dependencyBuilder);
53      }
54  
55      public T get() {
56          Constructor<T> constructor = getConstructor();
57          Object[] params = new Object[constructor.getParameterTypes().length];
58          for (Dependency<?> dependency : constructorInjectionPoint.getDependencies()) {
59              params[dependency.getParameterIndex()] = injector.getInstance(dependency.getKey());
60          }
61          T t;
62          try {
63              t = constructor.newInstance(params);
64          } catch (Exception e) {
65              throw new ProvisionException("Could not instantiate " + key + "", e);
66          }
67          injector.injectMembers(t);
68          return postProcess(t);
69      }
70  
71      @SuppressWarnings({"unchecked"})
72      private Constructor<T> getConstructor() {
73          return (Constructor<T>) constructorInjectionPoint.getMember();
74      }
75  
76      protected T postProcess(T t) {
77          // do nothing by default
78          return t;
79      }
80  
81      public Set<Dependency<?>> getDependencies() {
82          return dependencies;
83      }
84  }