原型模式:(复制对象) 1.复制"引用"与复制"对象"的区别 1.1复制"引用"---复制地址 假设被复制对象为a a,复制的新对象为a b. 复制引用的过程就是将a的地址值复制给b.a和b同时指向堆内存的同一个地址. 过程为:
1 a a = new a(); 2 a b = a;
这样,只要其中一个对象的属性发生变化,另一个对象的属性也随之发生变化.
根据"复制引用"编写程序:
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1 public class student {
2
3 public static void main(string[] args) {
4 student s1 = new student("张三", 23);
5 student s2 = s1;
6 system.out.println(s1 == s2);
7 system.out.println(s1);
8 system.out.println(s2);
9
10 //1.改变s1的名字
11 s1.setname("李四");
12 system.out.println(s1 == s2);
13 system.out.println(s1);
14 system.out.println(s2);
15
16 //1.改变s1的名字
17 s2.setname("王五");
18 system.out.println(s1 == s2);
19 system.out.println(s1);
20 system.out.println(s2);
21 }
22
23 private string name;
24 private int age;
25
26 public student() {}
27
28 public student(string name, int age) {
29 this.name = name;
30 this.age = age;
31 }
32
33 public string getname() {
34 return name;
35 }
36
37 public void setname(string name) {
38 this.name = name;
39 }
40
41 public int getage() {
42 return age;
43 }
44
45 public void setage(int age) {
46 this.age = age;
47 }
48
49 @override
50 public string tostring() {
51 return "student [name=" + name + ", age=" + age + "]";
52 }
53 }
程序运行结果:
1 true 2 student [name=张三, age=23] 3 student [name=张三, age=23] 4 5 true 6 student [name=李四, age=23] 7 student [name=李四, age=23] 8 9 true 10 student [name=王五, age=23] 11 student [name=王五, age=23]
1.2复制"对象"---复制内容
假设被复制对象为student s1,复制的新对象为student s2.
student类有两个属性,name 和 age;
复制对象的过程:
①:student s1 = new student("张三", 23);
②:student s2 = new student();
③:s2.setname(s1.getname());
s2.setage(s1.getage());
s1与s2是两个不同的对象,保存相同的属性及其属性值.当s1的属性值发生变化时,s2的属性值不会受到影响.s1与s2相互独立.
根据"复制对象的过程"编写程序:
1 public class student {
2
3 public static void main(string[] args) {
4 student s1 = new student("张三", 23);
5 student s2 = new student();
6
7 s2.setname(s1.getname());
8 s2.setage(s1.getage());
9 system.out.println(s1 == s2);
10 system.out.println(s1);
11 system.out.println(s2);
12
13 s1.setname("李四");
14 system.out.println(s1);
15 system.out.println(s2);
16
17 s2.setname("王五");
18 system.out.println(s1);
19 system.out.println(s2);
20 }
21
22 private string name;
23 private int age;
24
25 public student() {}
26
27 public student(string name, int age) {
28 this.name = name;
29 this.age = age;
30 }
31
32 public string getname() {
33 return name;
34 }
35
36 public void setname(string name) {
37 this.name = name;
38 }
39
40 public int getage() {
41 return age;
42 }
43
44 public void setage(int age) {
45 this.age = age;
46 }
47
48 @override
49 public string tostring() {
50 return "student [name=" + name + ", age=" + age + "]";
51 }
52 }
程序运行结果:
1 false 2 student [name=张三, age=23] 3 student [name=张三, age=23] 4 5 student [name=李四, age=23] 6 student [name=张三, age=23] 7 8 student [name=李四, age=23] 9 student [name=王五, age=23]
2.原型模式 2.1假设对象的属性特征很简单:(直接赋值,不需要new对象来赋值) 例:情况1.
1 class person{
2 private string name;
3 private int age;
4 }
那么:实现对象复制的过程很简单.
思路a:
①:person类实现cloneable接口.
cloneable是一个标识性接口,没有抽象方法.实现这个接口的类被标记为可以被克隆.
②:person类重写clone()方法.
根据思路a编写程序:
1 public class person implements cloneable{
2
3 public static void main(string[] args) throws clonenotsupportedexception {
4 // 测试
5 //原型
6 person person = new person("张三", 23);
7 //克隆对象
8 person cloneperson = (person)person.clone();
9 system.out.println(person == cloneperson);
10 system.out.println(person);
11 system.out.println(cloneperson);
12
13 //1.改变person的名字和对象
14 person.setname("李四");
15 person.setage(24);
16 system.out.println(person);
17 system.out.println(cloneperson);
18
19 //2.改变cloneperson的名字和对象
20 cloneperson.setname("王五");
21 cloneperson.setage(25);
22 system.out.println(person);
23 system.out.println(cloneperson);
24 }
25
26 private string name;
27 private int age;
28 public person(string name, int age) {
29 this.name = name;
30 this.age = age;
31 }
32 public person() {}
33 public string getname() {
34 return name;
35 }
36 public void setname(string name) {
37 this.name = name;
38 }
39 public int getage() {
40 return age;
41 }
42 public void setage(int age) {
43 this.age = age;
44 }
45 @override
46 public string tostring() {
47 return "person [name=" + name + ", age=" + age + "]";
48 }
49 public object clone() throws clonenotsupportedexception {
50 person person = (person)super.clone();
51 return person;
52 }
53 }
程序运行结果:
1 false 2 person [name=张三, age=23] 3 person [name=张三, age=23] 4 5 person [name=李四, age=24] 6 person [name=张三, age=23] 7 8 person [name=李四, age=24] 9 person [name=王五, age=25]
2.1假设对象的某些属性特征较复杂:(需要new对象来赋值)
例:情况2.
1 class person{
2 private string name;
3 private int age;
4 private company com;
5 }
6
7
8 class company{
9 private string name;
10 private int age;
11 private string address;
12 }
在情况2下能够采用思路a编程吗? 让我们来试一试:思路a
1 public class person implements cloneable{
2
3 public static void main(string[] args) throws clonenotsupportedexception {
4 // 测试
5 //1.创建原型对象
6 company com = new company("tencent", 5, "深圳");
7 person person = new person("张三", 23, com);
8 //原型克隆
9 person cloneperson = (person)person.clone();
10 system.out.println(person == cloneperson);
11 system.out.println(person);
12 system.out.println(cloneperson);
13
14 //2.改变原型对象的com
15 company personcom = person.getcom();
16 personcom.setname("alibaba");
17 personcom.setage(3);
18 personcom.setaddress("杭州");
19 system.out.println(person);
20 system.out.println(cloneperson);
21
22 //3.改变克隆对象的com
23 company clonepersoncom = cloneperson.getcom();
24 clonepersoncom.setname("baidu");
25 clonepersoncom.setage(4);
26 clonepersoncom.setaddress("beijing");
27 system.out.println(person);
28 system.out.println(cloneperson);
29 }
30
31 private string name;
32 private int age;
33 private company com;
34
35 public person() {}
36
37 public person(string name, int age, company com) {
38 this.name = name;
39 this.age = age;
40 this.com = com;
41 }
42
43 public string getname() {
44 return name;
45 }
46 public void setname(string name) {
47 this.name = name;
48 }
49 public int getage() {
50 return age;
51 }
52 public void setage(int age) {
53 this.age = age;
54 }
55 public company getcom() {
56 return com;
57 }
58
59 public void setcom(company com) {
60 this.com = com;
61 }
62
63 @override
64 public string tostring() {
65 return "person [name=" + name + ", age=" + age + ", com=" + com + "]";
66 }
67 public object clone() throws clonenotsupportedexception {
68 person person = (person)super.clone();
69 return person;
70 }
71 }
1 public class company implements cloneable{
2
3 private string name;
4 private int age;
5 private string address;
6 public company() {
7 }
8 public company(string name, int age, string address) {
9 this.name = name;
10 this.age = age;
11 this.address = address;
12 }
13 public string getname() {
14 return name;
15 }
16 public void setname(string name) {
17 this.name = name;
18 }
19 public int getage() {
20 return age;
21 }
22 public void setage(int age) {
23 this.age = age;
24 }
25 public string getaddress() {
26 return address;
27 }
28 public void setaddress(string address) {
29 this.address = address;
30 }
31
32 @override
33 public string tostring() {
34 return "company [name=" + name + ", age=" + age + ", address=" + address + "]";
35 }
36 }
程序运行结果:
1 false 2 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 3 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 4 5 person [name=张三, age=23, com=company [name=alibaba, age=3, address=杭州]] 6 person [name=张三, age=23, com=company [name=alibaba, age=3, address=杭州]] 7 8 person [name=张三, age=23, com=company [name=baidu, age=4, address=beijing]] 9 person [name=张三, age=23, com=company [name=baidu, age=4, address=beijing]]
这时会发现,已经有错误产生了. 当我们改动person或者cloneperson的com值时,另一个对象的com也会随之发生改变. 修改方法:思路b ①:person, company都要实现cloneable接口. ②:在对person对象进行克隆的同时也要对company对象进行克隆. 根据思路b编写程序:
1 public class person implements cloneable{
2
3 public static void main(string[] args) throws clonenotsupportedexception {
4 // 测试
5 //1.创建原型对象
6 company com = new company("tencent", 5, "深圳");
7 person person = new person("张三", 23, com);
8 //原型克隆
9 person cloneperson = (person)person.clone();
10 system.out.println(person == cloneperson);
11 system.out.println(person);
12 system.out.println(cloneperson);
13
14 //2.改变原型对象的com
15 company personcom = person.getcom();
16 personcom.setname("alibaba");
17 personcom.setage(3);
18 personcom.setaddress("杭州");
19 system.out.println(person);
20 system.out.println(cloneperson);
21
22 //3.改变克隆对象的com
23 company clonepersoncom = cloneperson.getcom();
24 clonepersoncom.setname("baidu");
25 clonepersoncom.setage(4);
26 clonepersoncom.setaddress("北京");
27 system.out.println(person);
28 system.out.println(cloneperson);
29 }
30
31 private string name;
32 private int age;
33 private company com;
34
35 public person() {}
36
37 public person(string name, int age, company com) {
38 this.name = name;
39 this.age = age;
40 this.com = com;
41 }
42
43 public string getname() {
44 return name;
45 }
46 public void setname(string name) {
47 this.name = name;
48 }
49 public int getage() {
50 return age;
51 }
52 public void setage(int age) {
53 this.age = age;
54 }
55 public company getcom() {
56 return com;
57 }
58
59 public void setcom(company com) {
60 this.com = com;
61 }
62
63 @override
64 public string tostring() {
65 return "person [name=" + name + ", age=" + age + ", com=" + com + "]";
66 }
67 public object clone() throws clonenotsupportedexception {
68 person person = (person)super.clone();//克隆person
69 person.setcom((company)com.clone());//克隆company
70 return person;
71 }
72 }
1 public class company implements cloneable{
2
3 private string name;
4 private int age;
5 private string address;
6 public company() {
7 }
8 public company(string name, int age, string address) {
9 this.name = name;
10 this.age = age;
11 this.address = address;
12 }
13 public string getname() {
14 return name;
15 }
16 public void setname(string name) {
17 this.name = name;
18 }
19 public int getage() {
20 return age;
21 }
22 public void setage(int age) {
23 this.age = age;
24 }
25 public string getaddress() {
26 return address;
27 }
28 public void setaddress(string address) {
29 this.address = address;
30 }
31
32 public object clone() throws clonenotsupportedexception{
33 return (company)super.clone();
34 }
35
36 @override
37 public string tostring() {
38 return "company [name=" + name + ", age=" + age + ", address=" + address + "]";
39 }
40 }
程序运行结果:
1 false 2 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 3 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 4 5 person [name=张三, age=23, com=company [name=alibaba, age=3, address=杭州]] 6 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 7 8 person [name=张三, age=23, com=company [name=alibaba, age=3, address=杭州]] 9 person [name=张三, age=23, com=company [name=baidu, age=4, address=北京]
根据思路b我们可以得到两个相互独立的对象. 但是,又产生了新的问题: 若是在com中还有类似于company的对象存在呢(内部还有很多属性和方法)? 若是在person中也有很多类似于company的对象存在呢? 若是继续采用思路b,写起来会非常麻烦,并且有可能会遗漏(某个对象也许没有被克隆的情况). 针对产生的新的问题,我们需要重新思考解决方案:思路c ①:person, company实现serializable接口. ②:采用对象流创建person对象. 根据思路c编写程序:
1 import java.io.bytearrayinputstream;
2 import java.io.bytearrayoutputstream;
3 import java.io.ioexception;
4 import java.io.objectinputstream;
5 import java.io.objectoutputstream;
6 import java.io.serializable;
7
8
9 public class person implements serializable{
10
11 public static void main(string[] args) throws clonenotsupportedexception, classnotfoundexception, ioexception {
12 // 测试
13 //1.创建原型对象
14 company com = new company("tencent", 5, "深圳");
15 person person = new person("张三", 23, com);
16 //原型克隆
17 person copyperson = person.getcopyperson();
18 system.out.println(person == copyperson);
19 system.out.println(person);
20 system.out.println(copyperson);
21
22 //2.person改变com的值
23 company personcom = person.getcom();
24 personcom.setname("alibaba");
25 personcom.setage(5);
26 personcom.setaddress("杭州");
27 system.out.println(person);
28 system.out.println(copyperson);
29
30 //3.copyperson改变com的值
31 company copypersoncom = copyperson.getcom();
32 copypersoncom.setname("baidu");
33 copypersoncom.setage(3);
34 copypersoncom.setaddress("北京");
35 system.out.println(person);
36 system.out.println(copyperson);
37 }
38
39 private string name;
40 private int age;
41 private company com;
42
43 public person() {}
44
45 public person(string name, int age, company com) {
46 this.name = name;
47 this.age = age;
48 this.com = com;
49 }
50
51 public string getname() {
52 return name;
53 }
54 public void setname(string name) {
55 this.name = name;
56 }
57 public int getage() {
58 return age;
59 }
60 public void setage(int age) {
61 this.age = age;
62 }
63 public company getcom() {
64 return com;
65 }
66
67 public void setcom(company com) {
68 this.com = com;
69 }
70
71 @override
72 public string tostring() {
73 return "person [name=" + name + ", age=" + age + ", com=" + com + "]";
74 }
75
76 public person getcopyperson() throws ioexception, classnotfoundexception {
77 // 创建输出流
78 bytearrayoutputstream bos = new bytearrayoutputstream();
79 objectoutputstream oos = new objectoutputstream(bos);
80 oos.writeobject(this);
81
82 // 创建输入流
83 bytearrayinputstream bis = new bytearrayinputstream(bos.tobytearray());
84 objectinputstream ois = new objectinputstream(bis);
85 object obj = ois.readobject();
86 return (person)obj;
87 }
88 }
1 import java.io.serializable;
2
3 public class company implements serializable{
4
5 private static final long serialversionuid = 1l;
6 private string name;
7 private int age;
8 private string address;
9 public company() {
10 }
11 public company(string name, int age, string address) {
12 this.name = name;
13 this.age = age;
14 this.address = address;
15 }
16 public string getname() {
17 return name;
18 }
19 public void setname(string name) {
20 this.name = name;
21 }
22 public int getage() {
23 return age;
24 }
25 public void setage(int age) {
26 this.age = age;
27 }
28 public string getaddress() {
29 return address;
30 }
31 public void setaddress(string address) {
32 this.address = address;
33 }
34
35 @override
36 public string tostring() {
37 return "company [name=" + name + ", age=" + age + ", address=" + address + "]";
38 }
39 }
程序运行结果:
1 false 2 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 3 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 4 5 person [name=张三, age=23, com=company [name=alibaba, age=5, address=杭州]] 6 person [name=张三, age=23, com=company [name=tencent, age=5, address=深圳]] 7 8 person [name=张三, age=23, com=company [name=alibaba, age=5, address=杭州]] 9 person [name=张三, age=23, com=company [name=baidu, age=3, address=北京]]
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