Java靜態代理和動態代理總結。本站提示廣大學習愛好者：（Java靜態代理和動態代理總結）文章只能為提供參考，不一定能成為您想要的結果。以下是Java靜態代理和動態代理總結正文
靜態代理
第一種實現(基於接口)：
1》接口
public interface Hello {
void say(String msg);
}
2》目標類，至少實現一個接口
public class HelloImpl implements Hello {
public void say(String msg) {
System.out.println("Hi,"+msg);
}
}
3》代理類(與目標類實現相同接口，從而保證功能一致)
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》測試
/**
* @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");
}
}
第二種實現(基於目標類)：
1>目標類
public class HelloTarget {
public void sayHello(String name){
System.out.println("Hi,"+name);
}
}
2>代理類(通過繼承目標類，保證功能一致)
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>測試
public class Main {
public static void main(String[] args) throws Exception {
HelloTarget target = new HelloTarget();
HelloProxy proxy= new HelloProxy(target);
proxy.sayHello("LZHL");
}
}
動態代理
動態代理的代理類是在程序運行期間動態生成的，也有兩種實現，一種是JDK動態代理，一種是CGLib動態代理
1》JDK動態代理(基於接口實現，與目標類實現相同接口，從而保證功能一致)
/**
* @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: 代理對象
* method: 目標對象的方法對象
* args: 目標對象方法的參數
* return: 目標對象方法的返回值
*/
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提取出來，單獨寫一個類，為了方便大家看，這裡我用內部類的形式
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動態代理(基於目標類，通過繼承目標類，從而保證功能一致)，需要導入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)目標類
public class Hi {
public void sayHi(String msg){
System.out.println("Hi,"+msg);
}
}
2)測試
/**
* @Author LZHL
* @Create 2017-02-19 13:19
* @Description
*/
public class Main {
public static void main(String[] args) {
Enhancer enhancer = new Enhancer();
//設置父類
enhancer.setSuperclass(Hi.class);
//設置回調函數
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提取出來，單獨寫一個類，為了方便大家看，這裡我用內部類的形式
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");
}
}
以上所述是小編給大家介紹的Java靜態代理和動態代理總結，希望對大家有所幫助，如果大家有任何疑問歡迎給我留言，小編會及時回復大家的！
