服务器之家:专注于服务器技术及软件下载分享
分类导航

PHP教程|ASP.NET教程|Java教程|ASP教程|编程技术|正则表达式|C/C++|IOS|C#|Swift|Android|VB|R语言|JavaScript|易语言|vb.net|

服务器之家 - 编程语言 - Java教程 - Java静态代理和动态代理总结

Java静态代理和动态代理总结

2020-08-14 15:52LZHL Java教程

这篇文章主要介绍了Java静态代理和动态代理总结,非常不错,具有参考借鉴价值,需要的朋友可以参考下

静态代理

第一种实现(基于接口):

1》接口

?
1
2
3
public interface Hello {
 void say(String msg);
}

2》目标类,至少实现一个接口

?
1
2
3
4
5
public class HelloImpl implements Hello {
 public void say(String msg) {
  System.out.println("Hi,"+msg);
 }
}

3》代理类(与目标类实现相同接口,从而保证功能一致)

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
public class HelloProxy implements Hello{
 private Hello hello;
 public HelloProxy(Hello hello){
  this.hello = hello;
 }
 public void say(String msg){
  before();
  hello.say(msg);
  after();
 }
 private void before(){
  System.out.println("Before");
 }
 private void after(){
  System.out.println("After");
 }
}

3》测试

?
1
2
3
4
5
6
7
8
9
10
11
12
/**
 * @Author LZHL
 * @Create 2017-02-19 10:26
 * @Description
 */
public class Main {
 public static void main(String[] args) throws Exception {
  HelloImpl target = new HelloImpl();
  HelloProxy proxy = new HelloProxy(target);
  proxy.say("LZHL");
 }
}

第二种实现(基于目标类):

1>目标类

?
1
2
3
4
5
public class HelloTarget {
 public void sayHello(String name){
  System.out.println("Hi,"+name);
 }
}

2>代理类(通过继承目标类,保证功能一致)

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
public class HelloProxy extends HelloTarget{
  private HelloTarget target;
  public HelloProxy(HelloTarget target){
    this.target = target;
  }
  @Override
 public void sayHello(String name) {
  this.before();
  target.sayHello(name);
  this.after();
 }
 private void before(){
  System.out.println("Before");
 }
 private void after(){
  System.out.println("After");
 }
}

3>测试

?
1
2
3
4
5
6
7
public class Main {
 public static void main(String[] args) throws Exception {
  HelloTarget target = new HelloTarget();
    HelloProxy proxy= new HelloProxy(target);
  proxy.sayHello("LZHL");
 }
}

动态代理

动态代理的代理类是在程序运行期间动态生成的,也有两种实现,一种是JDK动态代理,一种是CGLib动态代理

1》JDK动态代理(基于接口实现,与目标类实现相同接口,从而保证功能一致)

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
/**
 * @Author LZHL
 * @Create 2017-02-19 12:46
 * @Description
 */
public class Main {
 public static void main(String[] args){
  final HelloImpl target = new HelloImpl();
  Object proxyInstance = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), new InvocationHandler() {
   /*
    * proxy: 代理对象
    * method: 目标对象的方法对象
    * args: 目标对象方法的参数
    * return: 目标对象方法的返回值
    */
   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    System.out.println("before");
    Object retValue = method.invoke(target, args);
    System.out.println("after");
    return retValue;
   }
  });
  Hello proxy = (Hello) proxyInstance;
  proxy.say("LYX");
  //可以把InvocationHandler提取出来,单独写一个类,为了方便大家看,这里我用内部类的形式
  class JDKProxy implements InvocationHandler {
   private Object target;
   public JDKProxy(Object target){
    this.target = target;
   }
   public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    before();
    Object result = method.invoke(target, args);
    after();
    return result;
   }
   private void before(){
    System.out.println("Before");
   }
   private void after(){
    System.out.println("After");
   }
  }
  InvocationHandler ih = new JDKProxy(target);
  Object proxyInstance2 = Proxy.newProxyInstance(target.getClass().getClassLoader(), target.getClass().getInterfaces(), ih);
  Hello proxy2 = (Hello) proxyInstance2;
  proxy2.say("LZHL");
 }
}

2》CGLib动态代理(基于目标类,通过继承目标类,从而保证功能一致),需要导入cglib-3.2.4.jar包

pom.xml

?
1
2
3
4
5
6
7
8
<dependencies>
 <!-- https://mvnrepository.com/artifact/cglib/cglib -->
 <dependency>
  <groupId>cglib</groupId>
  <artifactId>cglib</artifactId>
  <version>3.2.4</version>
 </dependency>
</dependencies>

1)目标类

?
1
2
3
4
5
public class Hi {
 public void sayHi(String msg){
  System.out.println("Hi,"+msg);
 }
}

2)测试

?
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
/**
 * @Author LZHL
 * @Create 2017-02-19 13:19
 * @Description
 */
public class Main {
 public static void main(String[] args) {
  Enhancer enhancer = new Enhancer();
  //设置父类
  enhancer.setSuperclass(Hi.class);
  //设置回调函数
  enhancer.setCallback(new MethodInterceptor() {
   public Object intercept(Object target, Method method, Object[] args, MethodProxy methodProxy) throws Throwable {
    System.out.println("before");
    Object retValue = methodProxy.invokeSuper(target, args);
    System.out.println("after");
    return retValue;
   }
  });
  Object proxy = enhancer.create();
  Hi hi = (Hi) proxy;
  hi.sayHi("LXY");
  //可以把MethodInterceptor提取出来,单独写一个类,为了方便大家看,这里我用内部类的形式
  class CGLibProxy implements MethodInterceptor {
   public <T> T getProxy(Class<T> clazz){
    return (T) Enhancer.create(clazz, this);
   }
   public Object intercept(Object target, Method method, Object[] args, MethodProxy proxy) throws Throwable {
    before();
    Object result = proxy.invokeSuper(target, args);
    after();
    return result;
   }
   private void before(){
    System.out.println("Before");
   }
   private void after(){
    System.out.println("After");
   }
  }
  CGLibProxy cgLibProxy = new CGLibProxy();
  Hi hi2 = cgLibProxy.getProxy(Hi.class);
  hi2.sayHi("LZHL");
 }
}

以上所述是小编给大家介绍的Java静态代理和动态代理总结,希望对大家有所帮助,如果大家有任何疑问欢迎给我留言,小编会及时回复大家的!

原文链接:http://www.cnblogs.com/lzhl/p/6416063.html

延伸 · 阅读

精彩推荐