静态代理
第一种实现(基于接口)：
1》接口
public interface Hello {
void say(String msg);
}
2》目标类，至少实现一个接口
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)
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
/**
* @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
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)
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
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)
/**
* @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
<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
public class Hi {
public void sayHi(String msg){
System.out.println("Hi,"+msg);
}
}
2)测试
/**
* @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！
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