Java-马士兵动态代理模式

模拟jdk的动态代理的实现原理, 这些东西没有必要写出来，写项目的时候用不上，主要是面试和理解原理；

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有些工具可以直接生成二进制码，没有必要生成文件。

代理模式-聚合与继承方式比较

参考地址：http://www.cnblogs.com/shamgod/p/4591782.html

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一、概述

1.目标：要在Tank的move()方法做时间代理及日志代理(可以设想以后还要增加很多代理处理)，且代理间的顺序可活更换

2.思路：

(1)聚合：代理类聚合了被代理类，且代理类及被代理类都实现了movable接口，则可实现灵活多变，具体看代码

(2)继承：继承不够灵活，具体看代码

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二、代码

1.Movable.java

2.Tank.java

3.TankTimeProxy.java

4.TankLogProxy.java

5.Tank2Time.java

6.Tank3Log.java

7.Client.java

?1.Movable.java

1. public interface Movable {
2. ??public void move();
3. ?}

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2.Tank.java

1. import java.util.Random;
2. ?
3. public class Tank implements Movable {
4. ?
5. ????@Override
6. ????public void move() {
7. ????????System.out.println("Tank moving.......");
8. ????????try {
9. ????????????Thread.sleep(new Random().nextInt(5000));
10. ????????} catch (InterruptedException e) {
11. ????????????e.printStackTrace();
12. ????????}
13. ????}
14. ?
15. }

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3.TankTimeProxy.java

1. public class TankTimeProxy implements Movable {
2. ?
3. ????Movable m;
4. ?
5. ????public TankTimeProxy(Movable m) {
6. ????????this.m = m;
7. ????}
8. ?
9. ????@Override
10. ????public void move() {
11. ????????System.out.println("Time Proxy start...........");
12. ????????long start = System.currentTimeMillis();
13. ????????m.move();
14. ????????long end = System.currentTimeMillis();
15. ????????System.out.println("花费时间："+(end - start));
16. ????????System.out.println("Time Proxy end...........");
17. ????}
18. ?
19. }

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4.TankLogProxy.java

1. public class TankLogProxy implements Movable {
2. ????Movable m;
3. ????public TankLogProxy(Movable m) {
4. ????????this.m = m;
5. ????}
6. ????@Override
7. ????public void move() {
8. ????????System.out.println("Log Proxy start...........");
9. ????????m.move();
10. ????????System.out.println("Log Proxy end...........");
11. ????}
12. }

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5.Tank2Time.java

1. public class Tank2Time extends Tank {
2. ?
3. ????public void move(){
4. ????????System.out.println("Tank2 time start...........");
5. ????????long start = System.currentTimeMillis();
6. ????????super.move();
7. ????????long end = System.currentTimeMillis();
8. ????????System.out.println("花费时间："+(end - start));
9. ????????System.out.println("Tank2 time end...........");
10. ????}
11. }

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6.Tank3Log.java

1. public class Tank3Log extends Tank2Time {
2. ?
3. ????public void move(){
4. ????????System.out.println("Tank3Log start...........");
5. ????????super.move();
6. ????????System.out.println("Tank3Log end...........");
7. ????}
8. }

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7.Client.java

1. public class Client {
2. ?
3. ????@Test
4. ????public void testProxy(){
5. ????????Tank t = new Tank();
6. ????????Movable m;
7. ????????//一、聚合的方式(较灵活，因为实现了接口)
8. ????????//1.1聚合方式的代理,先日志代理，后时间代理
9. ????????TankTimeProxy ttp1 = new TankTimeProxy(t);
10. ????????TankLogProxy tlp1 = new TankLogProxy(ttp1);
11. ????????m = tlp1;
12. ????????m.move();
13. ????????System.out.println("\n==============================分隔线==========================\n");
14. ????????//1.2聚合方式的代理,先时间代理，后日志代理(可以灵活切换顺序)
15. ????????TankLogProxy tlp2 = new TankLogProxy(t);
16. ????????TankTimeProxy ttp2 = new TankTimeProxy(tlp2);
17. ????????m = ttp2;
18. ????????m.move();
19. ????????System.out.println("\n==============================分隔线==========================\n");
20. ????????//二、继承的方式
21. ????????//2.1代理时间
22. ????????Tank2Time t2 = new Tank2Time();
23. ????????t2.move();
24. ????????System.out.println("\n==============================分隔线==========================\n");
25. ????????//2.2先代理日志，后时间，不能灵活切换
26. ????????Tank3Log t3 = new Tank3Log();
27. ????????t3.move();
28. ????}
29. }

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三、运行结果

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四、小结

凡是要求灵活多变的功能，多数用接口多态实现

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组合方式实现代理的缺点：每实现一个需求都需要写一个代理类，比如：为了实现在方法前后加日志TankLogProxy、为了实现记录方法运行时间TankTimeProxy，随着系统的复杂，如果还需要实现权限、事务管理，用这种设计方法，代理类会越来越多。有没有一种方式，能够让我们不写这些代理类？ 动态代理，动态的去代理，代理类是动态生成的，不需要我们编写，这样就可以解决这个代理类很多的问题，这样会极大地减少了我们的工作。

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代理模式-动态代理 调用Proxy.newProxyInstance()

http://www.cnblogs.com/shamgod/p/4592014.html

一、概述

1.目标：不自己写代理类，利用Proxy.newProxyInstance()动态生成

2.用到的知识点：

(1)//编译源码，生成class,注意编译环境要换成jdk1.6才有compiler,单纯的jre没有compiler，会空指针错误

JavaCompiler jc = ToolProvider.getSystemJavaCompiler();
(2)//文件管事器
StandardJavaFileManager fileMgr = jc.getStandardFileManager(null, null, null);
(3)//编译单元
Iterable units = fileMgr.getJavaFileObjects(file);
(4)//编译任务
CompilationTask t = jc.getTask(null, fileMgr, null, null, null, units);

(5)//编译
t.call();

(6)//把类load到内存里

URL[] urls = new URL[] {new URL("file:/"+System.getProperty("user.dir")+"/src/proxy/TankTimeProxy.class")};
URLClassLoader uc = new URLClassLoader(urls);
Class c = uc.loadClass("proxy.TankTimeProxy");

(7)//生成实例

//return c.newInstance(); //c.newInstance()会调用无参数的Construtor，若类没有无参的Constructor时会出错
Constructor ctr = c.getConstructor(Movable.class);
return ctr.newInstance(new Tank());

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二、代码

1.Movable.java

2.Tank.java

3.Proxy.java

4.Client.java

?1.Moveable.java

1. package com.weiqinshian.proxy;
2. public interface Moveable
3. {
4. ???public void move();
5. }

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2.Tank.java

1. package com.weiqinshian.proxy;
2. import java.util.Random;
3. public class Tank implements Moveable
4. {
5. ???@Override
6. ???public void move()
7. ???{
8. ??????System.out.println("tank move........");
9. ??????try
10. ??????{
11. ?????????Thread.sleep(new Random().nextInt(10000));
12. ??????} catch (InterruptedException e)
13. ??????{
14. ?????????e.printStackTrace();
15. ??????}
16. ???}
17. }

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3.Proxy.java

1. package com.weiqinshian.proxy;
2. import java.io.File;
3. import java.io.FileWriter;
4. import java.lang.reflect.Constructor;
5. import java.net.URL;
6. import java.net.URLClassLoader;
7. import javax.tools.JavaCompiler;
8. import javax.tools.StandardJavaFileManager;
9. import javax.tools.ToolProvider;
10. import javax.tools.JavaCompiler.CompilationTask;
11. public class Proxy
12. {
13. ???public static Object newProxyInstance() throws Exception
14. ???{
15. ??????String rt = "\n\r";
16. ??????// 动态代理文件的源码
17. ??????String str = "package com.weiqinshian.proxy;" + rt +
18. ??????"public class TankTimeProxy implements Moveable {" + rt +
19. ??????"private Moveable m;" + rt +
20. ??????"public TankTimeProxy(Moveable m) {" + rt + "this.m = m;" + rt + "}" + rt +
21. ??????"@Override" + rt + "public void move() {" + rt + "System.out.println(\"Time Proxy start...........\");" + rt + "long start = System.currentTimeMillis();" + rt + "m.move();" + rt
22. ????????????+ "long end = System.currentTimeMillis();" + rt + "System.out.println(\"花费时间：\"+(end - start));" + rt + "System.out.println(\"Time Proxy end...........\");" + rt + "}" + rt +
23. ????????????"}";
24. ??????// 把源码写到java文件里
25. ??????File file = new File("d:/src/com/weiqinshian/proxy/TankTimeProxy.java");
26. ??????FileWriter fw = new FileWriter(file);
27. ??????fw.write(str);
28. ??????fw.flush();
29. ??????fw.close();
30. ??????// 编译源码，生成class,注意编译环境要换成jdk才有compiler,单纯的jre没有compiler，会空指针错误
31. ??????JavaCompiler jc = ToolProvider.getSystemJavaCompiler();
32. ??????// 文件管事器
33. ??????StandardJavaFileManager fileMgr = jc.getStandardFileManager(null, null, null);
34. ??????// 编译单元
35. ??????Iterable units = fileMgr.getJavaFileObjects(file);
36. ??????// 编译任务
37. ??????CompilationTask t = jc.getTask(null, fileMgr, null, null, null, units);
38. ??????// 编译
39. ??????t.call();
40. ??????fileMgr.close();
41. ??????// 把类load到内存里src\com\weiqinshian\proxy
42. ??????URL[] urls = new URL[]
43. ??????{ new URL("file:/" + "d:/src/") };
44. ??????System.out.println("file:/" + System.getProperty("user.dir") + "/src/com/weiqinshian/proxy/TankTimeProxy.class");
45. ??????URLClassLoader uc = new URLClassLoader(urls);
46. ??????Class c = uc.loadClass("com.weiqinshian.proxy.TankTimeProxy");
47. ??????// 生成实例
48. ??????// return c.newInstance();
49. ??????// //c.newInstance()会调用无参数的Construtor，若类没有无参的Constructor时会出错
50. ??????Constructor ctr = c.getConstructor(Moveable.class);
51. ??????return ctr.newInstance(new Tank());
52. ???}
53. }

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4.Client.java

1. ?package com.weiqinshian.proxy;
2. public class Client
3. {
4. ???public static void main(String[] args) throws Exception
5. ???{
6. ??????Moveable m = (Moveable) Proxy.newProxyInstance();
7. ??????m.move();// 感觉没有生成任何代理类
8. ???}
9. }

三、运行结果

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这种方式存在的问题：现在动态代理，动态生成的代理类是写死了的，是用字符串写死在类里面的，而且，只能动态生成实现了 Moveable接口的代理，如果要实现任意接口的代理应该怎么办？ 那就不将动态生成代理类的字符串写死，动态拼接生成代理类。

代理模式--动态代理 修改成可以代理任意接口

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一、概述

1.目标：把Proxy修改成可以代理任意接口及其任意方法,只要传接口名给newProxyInstance，就能动态生成实现了该接口的代理类。

2.思路：

(1)代理任意接口：把接口类型作为参数传给Proxy的newProxyInstance(Class interfze)

(2)代理任意方法：用interfze.getMethods()取出所有方法，拼接实现方法的字符串

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二、代码

1.Movable.java

2.Tank.java

3.Proxy.java

4.Client.java

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1.Movable.java

1. package com.weiqinshian.proxy;
2. public interface Moveable
3. {
4. ???public void move();
5. ???public void stop();
6. }

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2.Tank.java

1. package com.weiqinshian.proxy;
2. import java.util.Random;
3. public class Tank implements Moveable
4. {
5. ???@Override
6. ???public void move()
7. ???{
8. ??????System.out.println("tank move........");
9. ??????try
10. ??????{
11. ?????????Thread.sleep(new Random().nextInt(10000));
12. ??????} catch (InterruptedException e)
13. ??????{
14. ?????????e.printStackTrace();
15. ??????}
16. ???}
17. ???public void stop()
18. ???{
19. ??????System.out.println("Tank stopping.......");
20. ???}
21. }

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3.Proxy.java

1. package com.weiqinshian.proxy;
2. import java.io.File;
3. import java.io.FileWriter;
4. import java.lang.reflect.Constructor;
5. import java.lang.reflect.Method;
6. import java.net.URL;
7. import java.net.URLClassLoader;
8. import javax.tools.JavaCompiler;
9. import javax.tools.StandardJavaFileManager;
10. import javax.tools.ToolProvider;
11. import javax.tools.JavaCompiler.CompilationTask;
12. ?
13. public class Proxy
14. {
15. ???public static Object newProxyInstance(Class interfze) throws Exception
16. ???{
17. ??????String rt = "\n\r";
18. ??????// 拼接"实现接口方法"的字符串
19. ??????String methodStr = "";
20. ??????for (Method m : interfze.getMethods())
21. ??????{
22. ?????????// 取出方法的修饰符和返回值类型
23. ?????????String[] parts = m.toString().replace("abstract ", "").split("\\.");
24. ?????????String[] parts2 = parts[0].split(" ");
25. ?????????methodStr += "@Override" + rt + parts2[0] + " " + parts2[1] + " " + m.getName() + "() {" + rt + "System.out.println(\"Time Proxy start...........\");" + rt
26. ???????????????+ "long start = System.currentTimeMillis();" + rt + "m." + m.getName() + "();" + rt + "long end = System.currentTimeMillis();" + rt
27. ???????????????+ "System.out.println(\"花费时间：\"+(end - start));" + rt + "System.out.println(\"Time Proxy end...........\");" + rt + "}";
28. ??????}
29. ??????// 动态代理文件的源码
30. ??????String str = "package com.weiqinshian.proxy; " + rt +
31. ??????"public class TankTimeProxy implements " + interfze.getName() + " {" + rt +
32. ??????"private " + interfze.getName() + " m;" + rt +
33. ??????"public TankTimeProxy(" + interfze.getName() + " m) {" + rt + "this.m = m;" + rt + "}" + rt +
34. ??????methodStr + rt +
35. ??????"}";
36. ??????// 把源码写到java文件里
37. ??????File file = new File("d:/src/com/weiqinshian/proxy/TankTimeProxy.java");
38. ??????FileWriter fw = new FileWriter(file);
39. ??????fw.write(str);
40. ??????fw.flush();
41. ??????fw.close();
42. ??????// 编译源码，生成class,注意编译环境要换成jdk才有compiler,单纯的jre没有compiler，会空指针错误
43. ??????JavaCompiler jc = ToolProvider.getSystemJavaCompiler();
44. ??????// 文件管事器
45. ??????StandardJavaFileManager fileMgr = jc.getStandardFileManager(null, null, null);
46. ??????// 编译单元
47. ??????Iterable units = fileMgr.getJavaFileObjects(file);
48. ??????// 编译任务
49. ??????CompilationTask t = jc.getTask(null, fileMgr, null, null, null, units);
50. ??????// 编译
51. ??????t.call();
52. ??????fileMgr.close();
53. ??????// 把类load到内存里src\com\weiqinshian\proxy
54. ??????URL[] urls = new URL[]
55. ??????{ new URL("file:/" + "d:/src/") };
56. ??????System.out.println("file:/" + System.getProperty("user.dir") + "/src/com/weiqinshian/proxy/TankTimeProxy.class");
57. ??????URLClassLoader uc = new URLClassLoader(urls);
58. ??????Class c = uc.loadClass("com.weiqinshian.proxy.TankTimeProxy");
59. ??????// 生成实例
60. ??????// return c.newInstance();
61. ??????// //c.newInstance()会调用无参数的Construtor，若类没有无参的Constructor时会出错
62. ??????Constructor ctr = c.getConstructor(interfze);
63. ??????return ctr.newInstance(new Tank());
64. ???}
65. }

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4.Client.java

1. package com.weiqinshian.proxy;
2. ?
3. public class Client
4. {
5. ???public static void main(String[] args) throws Exception
6. ???{
7. ??????Moveable m = (Moveable) Proxy.newProxyInstance(Moveable.class);// 方法参数可以传任意接口类型
8. ??????m.move();
9. ??????m.stop();
10. ???}
11. }

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三、运行结果

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代理模式-动态代理 修改成可以任意修改代理逻辑

一、概述

1.目标：动态代理的代理逻辑可以任意修改

2.思路：

(1)要把代理逻辑抽离，站在jvm的角度思考，应独立出InvocationHandler接口，并接收被代理的对象及方法作为参数invoke(Object o, Method m)，并本身作为参数传给newProxyInstance(Class interfze,InvocationHandler handler)?

(2)InvocationHandler本身聚合被代理类target，以便在target的方法前后增加代理逻辑

3.知识点：

(1)按名字找方法java.lang.reflect.Method md = proxy.Movable.class.getMethod("stop");

(2)按"."拆分字符串：String [] parts = m.toString().replace("abstract ", "").split("\\.");

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二、代码

1.InvocationHandler.java

2.TimeHandler.java

3.Movable.java

4.Tank.java

5.Proxy.java

6.Client.java

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1.InvocationHandler.java

1 package proxy;

2

3 import java.lang.reflect.Method;

4

5 public interface InvocationHandler {

6 public void invoke(Object o, Method m);

7 }

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2.TimeHandler.java

1 package proxy;

2

3 import java.lang.reflect.InvocationTargetException;

4 import java.lang.reflect.Method;

5

6 public class TimeHandler implements InvocationHandler {

7

8 //保留被代理的对象

9 private Object target;

10

11 public TimeHandler(Object target) {

12 this.target = target;

13 }

14

15 @Override

16 public void invoke(Object o, Method m) {

17 System.out.println("Time Proxy start...........");

18 long start = System.currentTimeMillis();

19 try {

20 //除了静态方法，方法的调用都要先已知对象，所以要把对象o作为参数传进去

21 m.invoke(target);

22 } catch (Exception e) {

23 e.printStackTrace();

24 }

25 long end = System.currentTimeMillis();

26 System.out.println("花费时间："+(end - start));

27 System.out.println("Time Proxy end...........");

28

29 }

30

31 }

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3.Movable.java

1 package proxy;

2

3 public interface Movable {

4 public void move();

5 public void stop();

6 }

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4.Tank.java

1 package proxy;

2

3 import java.util.Random;

4

5 public class Tank implements Movable {

6

7 @Override

8 public void move() {

9 System.out.println("Tank moving.......");

10 try {

11 Thread.sleep(new Random().nextInt(2000));

12 } catch (InterruptedException e) {

13 e.printStackTrace();

14 }

15 }

16

17 @Override

18 public void stop() {

19 System.out.println("Tank stopping.......");

20

21 }

22

23 }

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5.Proxy.java

1 package proxy;

2

3 import java.io.File;

4 import java.io.FileWriter;

5 import java.lang.reflect.Constructor;

6 import java.lang.reflect.Method;

7 import java.net.URL;

8 import java.net.URLClassLoader;

9

10 import javax.tools.JavaCompiler;

11 import javax.tools.JavaCompiler.CompilationTask;

12 import javax.tools.StandardJavaFileManager;

13 import javax.tools.ToolProvider;

14

15 public class Proxy {

16//InvocationHandler ,代理的类型，调用的时候，你要告诉我，你想产生的是什么类型（日志、权限、时间）的代理

17 public static Object newProxyInstance(Class interfze,InvocationHandler handler) throws Exception {

18

19 String rt = "\n\r";

20

21 //拼接"实现接口方法"的字符串

22 String methodStr = "";

23 for(Method m: interfze.getMethods() ){

24

25 //取出方法的修饰符和返回值类型

26 String [] parts = m.toString().replace("abstract ", "").split("\\.");

27 String [] parts2 = parts[0].split(" ");

28

29 methodStr +=

30 "@Override" + rt +

31 parts2[0]+" "+parts2[1]+" "+m.getName()+"() {" + rt +

32 "try{"+ rt +

33 "java.lang.reflect.Method md = " + interfze.getName() + ".class.getMethod(\""+m.getName()+"\");" + rt +

34 //传this进去其实没什么用，invoke实际是调用target的方法m.invoke(target)

35 "handler.invoke(this, md);" + rt +

36 "}catch(Exception e){"+ rt +

37 " e.printStackTrace();" + rt +

38 "}" + rt +

39

40

41 "}"+ rt ;

42 }

43

44

45 //动态代理文件的源码

46 String str =

47 "package proxy;" + rt +

48

49 "public class TankTimeProxy implements " + interfze.getName() + " {"+rt+

50

51

52 //聚合Handler

53 "private InvocationHandler handler;" + rt +

54

55 "public TankTimeProxy(InvocationHandler handler) {" + rt +

56 "this.handler = handler;" + rt +

57 "}" + rt +

58

59 methodStr + rt +

60

61 "}" ;

62

63 //把源码写到java文件里

64 File file = new File(System.getProperty("user.dir")+"/src/proxy/TankTimeProxy.java");

65 FileWriter fw = new FileWriter(file);

66 fw.write(str);

67 fw.flush();

68 fw.close();

69

70 //编译源码，生成class,注意编译环境要换成jdk才有compiler,单纯的jre没有compiler，会空指针错误

71 JavaCompiler jc = ToolProvider.getSystemJavaCompiler();

72

73 //文件管事器

74 StandardJavaFileManager fileMgr = jc.getStandardFileManager(null, null, null);

75

76 //编译单元

77 Iterable units = fileMgr.getJavaFileObjects(file);

78

79 //编译任务

80 CompilationTask t = jc.getTask(null, fileMgr, null, null, null, units);

81

82 //编译

83 t.call();

84 fileMgr.close();

85

86 //把类load到内存里

87 URL[] urls = new URL[] {new URL("file:/"+System.getProperty("user.dir")+"/src/proxy/TankTimeProxy.class")};

88 URLClassLoader uc = new URLClassLoader(urls);

89 Class c = uc.loadClass("proxy.TankTimeProxy");

90

91 //生成实例

92 //return c.newInstance(); //c.newInstance()会调用无参数的Construtor，若类没有无参的Constructor时会出错

93 //Constructor ctr = c.getConstructor(interfze);

94 Constructor ctr = c.getConstructor(InvocationHandler.class);

95 return ctr.newInstance(handler);

96 }

97 }

??

6.Client.java

1 package proxy;

2

3 import java.io.IOException;

4

5 import org.junit.Test;

6

7 public class Client {

8

9 @Test

10 public void testProxy() throws Exception{

11

12 Movable m = (Movable)Proxy.newProxyInstance(Movable.class, new TimeHandler(new Tank()));

13 m.move();

14 m.stop();

15

16 }

17 }

??

三、运行结果

Java-马士兵动态代理模式