Strategy 定义一系列算法或策略,把它们封闭起来,并且使它们相互可以替换。各算法或策略可以独立于客户程序而变化。
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
1
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
2
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
3
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
4
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
5
![](https://www.cnblogs.com/Images/OutliningIndicators/None.gif)
6
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
7
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
8
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
9
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
10
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
11
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
12
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
13
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
14
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
15
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
16
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
17
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
18
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
19
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
20
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
21
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
22
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
23
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
24
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
25
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
26
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
27
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
28
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
29
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
30
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
31
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
32
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
33
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
34
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
35
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
36
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
37
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
38
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
39
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
40
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
41
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
42
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
43
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
44
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
45
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
46
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
47
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
48
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
49
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
50
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
51
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
52
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
53
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
54
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
55
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
56
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
57
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockStart.gif)
![](https://www.cnblogs.com/Images/OutliningIndicators/ContractedSubBlock.gif)
![](https://www.cnblogs.com/Images/dot.gif)
58
![](https://www.cnblogs.com/Images/OutliningIndicators/InBlock.gif)
59
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
60
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedSubBlockEnd.gif)
61
![](https://www.cnblogs.com/Images/OutliningIndicators/ExpandedBlockEnd.gif)
We can see three design principle:
1.Identify the aspects of your application that vary and separate them from what stays the same.
2.Program to an interface, not an implemention.
3.Favor composition over inheritance.
Can you see it?
![](http://www.cnblogs.com/images/cnblogs_com/nanshouyong326/90398/o_20080126(020).jpg)