Java JDK动态代理实现原理实例解析

/**
 * @CreateDate: 2019/6/17 14:52
 * @Version: 1.0
 */
public interface BuyService {
  String buyPhone();
  String buyComputer();
}

public class BuyServiceImpl implements BuyService {

  @Intercept("buyPhone")
  @Override
  public String buyPhone() {
    try {
      TimeUnit.SECONDS.sleep(1);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    System.out.println("==========BuyServiceImpl.class=============" + " buyPhone");
    this.buyComputer();
    return "buy phone";
  }

  @Intercept("buyComputer")
  @Override
  public String buyComputer() {
    try {
      TimeUnit.SECONDS.sleep(1);
    } catch (InterruptedException e) {
      e.printStackTrace();
    }
    System.out.println("==========BuyServiceImpl.class=============" + " buyComputer");
    return "buy computer";
  }
}

public class ReflectionHandler implements InvocationHandler {

  private Object target;

  public ReflectionHandler(Object target) {
    this.target = target;
  }

  public <T> T getProxy(){
    return (T) Proxy.newProxyInstance(this.getClass().getClassLoader(),target.getClass().getInterfaces(),this);
  }

  @Override
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    return method.invoke(target,args);
  }
}

public class Bootstrap {

  public static void main(String[] args) {

    // 动态代理实现
    ReflectionHandler reflectionHandler = new ReflectionHandler(new BuyServiceImpl());

    BuyService proxy = reflectionHandler.getProxy();

    String computer = proxy.buyComputer();

    String phone = proxy.buyPhone();

    System.out.println(computer + "\r\n" + phone);
  }