Android5.1 中智能指针涉及的文件如下：
system/core/include/utils/RefBase.h
system/core/libutils/RefBase.cpp
system/core/include/utils/StrongPointer.h
在学习Android的智能指针时，对于模板的使用不太清楚，于是我将sp类精简了一下，大概看一下在赋值和初始化的时候的函数调用关系：
1 #include <iostream>
2
3 using namespace std;
4
5 template<typename T>
6 class sp {
7 public:
8 inline sp() {};
9 sp(T* other);
10 sp(const sp<T>& other);
11 template<typename U> sp(U* other);
12 template<typename U> sp(const sp<U>& other);
13
14 ~sp();
15
16 sp& operator = (T* other);
17 sp& operator = (const sp<T>& other);
18 template<typename U> sp& operator = (const sp<U>& other);
19 template<typename U> sp& operator = (U* other);
20 };
21
22 template<typename T>
23 sp<T>::sp(T* other) {
24 cout << "enter sp(T* other) " << endl;
25 }
26
27 template<typename T>
28 sp<T>::sp(const sp<T>& other) {
29 cout << "enter sp(const sp<T>& other) " << endl;
30 }
31
32 template<typename T> template<typename U>
33 sp<T>::sp(U* other) {
34 cout << "enter sp(U *other) " << endl;
35 }
36
37 template<typename T> template<typename U>
38 sp<T>::sp(const sp<U>& other) {
39 cout << "sp(const sp<U& other>)" << endl;
40 }
41
42 template<typename T>
43 sp<T>::~sp() {
44 }
45
46 template<typename T>
47 sp<T>& sp<T>::operator =(T* other) {
48 cout << "enter operator =(T* other) " << endl;
49 return *this;
50 }
51
52
53 template<typename T>
54 sp<T>& sp<T>::operator =(const sp<T>& other) {
55 cout << "enter operator = (const sp<T>& other)" << endl;
56 return *this;
57 }
58
59 template<typename T> template<typename U>
60 sp<T>& sp<T>::operator =(const sp<U>& other) {
61 cout << "operator = (const sp<U>& other)" << endl;
62 return *this;
63 }
64
65 template<typename T> template<typename U>
66 sp<T>& sp<T>::operator =(U* other) {
67 cout << "operator = (U* other)" << endl;
68 return *this;
69 }
70
71 class Peng{
72 };
73
74 class Dong {
75 };
76
77 int main(int argc, const char *argv[])
78 {
79 Peng *p = new Peng();
80 Dong *d = new Dong();
81
82 cout << "---- sp<Peng> q = p ----" << endl;
83 sp<Peng> q = p;
84
85 cout << "
---- sp<Peng> r(p) ----" << endl;
86 sp<Peng> r(p);
87
88 cout << "
---- sp<Peng> b(r) ----" << endl;
89 sp<Peng> b(r);
90
91 cout << "
---- sp<Peng> t; ----" << endl;
92 sp<Peng> t;
93 cout << "
---- t = p ----" << endl;
94 t = p;
95
96 cout << "
---- sp<Peng> a; ----" << endl;
97 sp<Peng> a;
98 cout << "
---- a = t ----" << endl;
99 a = t;
100
101 Dong *c = new Dong();
102 cout << "
---- sp<Dong> e = c ----" << endl;
103 sp<Dong> e = c;
104 cout << "
---- a = e ----" << endl;
105 a = e;
106 cout << "
---- a = c ----" << endl;
107 a = c;
108
109 cout << "
---- sp<Dong> e1(e) ----" << endl;
110 sp<Peng> e1(e);
111
112 cout << endl << endl;
113 return 0;
114 }
下面是在PC机上的运行结果：
pengdl@pengdl-HP:~/work/study/c++$ ./a.out
---- sp<Peng> q = p ----
enter sp(T* other)
---- sp<Peng> r(p) ----
enter sp(T* other)
---- sp<Peng> b(r) ----
enter sp(const sp<T>& other)
---- sp<Peng> t; ----
---- t = p ----
enter operator =(T* other)
---- sp<Peng> a; ----
---- a = t ----
enter operator = (const sp<T>& other)
---- sp<Dong> e = c ----
enter sp(T* other)
---- a = e ----
operator = (const sp<U>& other)
---- a = c ----
operator = (U* other)
---- sp<Dong> e1(e) ----
sp(const sp<U& other>)
完。