public class User {
    private String name;
    public Integer age;
    public User(){}
    private User(String name) {
        this.name = name;
    }
    public String getName() {
        return name;
    }
    private void setAge(Integer age) {
        this.age = age;
    }
}

        //1.類名.class(編譯時(shí)確定，最高效)
        Class<?> class1 = User.class;
        System.out.println(class1); //class User
        //2.對(duì)象.getClass() (運(yùn)行時(shí)獲取，需要實(shí)例化)
        User user = new User();
        Class<?> class2 = user.getClass();
        System.out.println(class2); //class User
        //3.Class.forName("全類名") (運(yùn)行時(shí)加載，最靈活)
        Class<?> class3 = Class.forName("User");
        System.out.println(class3); //class User
        //判斷上面三種方法獲取的是否是同一個(gè)對(duì)象
        System.out.println(class1.equals(class2)); //true

//1.獲取類
        Class<User> userClass = User.class;
        //2.獲取構(gòu)造器
        //2.1獲取公共構(gòu)造器
        Constructor<?>[] publicConstructors = userClass.getConstructors();
        System.out.println(Arrays.toString(publicConstructors)); //[public User()]
        //2.2獲取所有構(gòu)造器
        Constructor<?>[] declaredConstructors = userClass.getDeclaredConstructors();
        System.out.println(Arrays.toString(declaredConstructors)); //[public User(), private User(java.lang.String)]
        //2.3獲取一個(gè)公共構(gòu)造器 (可以傳遞參數(shù)，參數(shù)是構(gòu)造器中的形參類)
        Constructor<User> constructor = userClass.getConstructor();
        System.out.println(constructor); //public User()
        //2.4獲取一個(gè)構(gòu)造器 (可以傳遞參數(shù)，參數(shù)是構(gòu)造器中的形參類)
        Constructor<User> declaredConstructor = userClass.getDeclaredConstructor(String.class);
        System.out.println(declaredConstructor); // private User(java.lang.String)

//2.4獲取一個(gè)構(gòu)造器
		Constructor<User> declaredConstructor = userClass.getDeclaredConstructor(String.class);
        System.out.println(declaredConstructor); // private User(java.lang.String)
		//3.Constructor類常用方法
        //3.1獲取構(gòu)造器的權(quán)限修飾符
        int modifiers = declaredConstructor.getModifiers();
        System.out.println(declaredConstructor + "的構(gòu)造方法的修飾符為" + modifiers);//private User(java.lang.String)的構(gòu)造方法的修飾符為2(對(duì)應(yīng)private)
        //3.2獲取構(gòu)造器的形參類型
        Class<?>[] types = declaredConstructor.getParameterTypes();
        System.out.println(declaredConstructor + "的形參類型有" + Arrays.toString(types)); //private User(java.lang.String)的形參類型有[class java.lang.String]
        //3.3通過(guò)Constructor實(shí)例化對(duì)象
        //因?yàn)楂@取的是私有方法，所以需要暴力反射
        declaredConstructor.setAccessible(true);//將私有構(gòu)造器設(shè)置為可訪問(wèn)狀態(tài)
        User user = declaredConstructor.newInstance( "無(wú)止境"); 
        System.out.println(user.getName()); //無(wú)止境

    //1.獲取類
        Class<User> userClass = User.class;
        //2.實(shí)例私有構(gòu)造器
        Constructor<User> privateConstructor = userClass.getDeclaredConstructor(String.class);
        privateConstructor.setAccessible(true);
        User user = privateConstructor.newInstance("無(wú)止境");
        //3.調(diào)用私有化方法setAge
        Method setAge = userClass.getDeclaredMethod("setAge", Integer.class);
        setAge.setAccessible(true);
        setAge.invoke(user, 18);
        System.out.println(user.getName() + "的年齡為" + user.getAge()); //無(wú)止境的年齡為18
        //4.獲取私有屬性 name
        Field nameField = userClass.getDeclaredField("name");
        nameField.setAccessible(true);
        String name = (String)nameField.get(user);
        System.out.println("利用反射獲取的私有屬性" + name); //利用反射獲取的私有屬性無(wú)止境

//目標(biāo)接口
public interface UserService {
    void addUser(String name);
    void deleteUser(Integer id);
}
//目標(biāo)實(shí)現(xiàn)類
public class UserServiceImpl implements UserService {
   @Override
    public void addUser(String name) {
        System.out.println("執(zhí)行添加姓名為 : " + name + " 用戶的操作");
    }
    @Override
    public void deleteUser(Integer id) {
        System.out.println("執(zhí)行刪除id為 : " + id + " 用戶的操作");
    }
}

public class LogInvocationHandler implements InvocationHandler {
    private Object target; //目標(biāo)對(duì)象
    public LogInvocationHandler(Object target) {
        this.target = target;
    }
    /**
     *
     * @param proxy 代理對(duì)象
     * @param method 目標(biāo)方法
     * @param args 方法參數(shù)
     * @return 方法返回值
     * @throws Throwable
     */
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        //前置日志,記錄日志
        System.out.println("【日志】 開(kāi)始調(diào)用方法 : " + method.getName() + ",方法參數(shù)為 : " + Arrays.toString(args));
        //調(diào)用目標(biāo)方法
        Object result = method.invoke(target, args);
        //后置日志，記錄方法完成
        System.out.println("【日志】方法調(diào)用結(jié)束 : " + method.getName());
        return result;
    }
}

public static void main(String[] args) {
        //1.創(chuàng)建目標(biāo)對(duì)象
        UserServiceImpl target = new UserServiceImpl();
        //2.創(chuàng)建InvocationHandler實(shí)例
        LogInvocationHandler handler = new LogInvocationHandler(target);
        //3.生成動(dòng)態(tài)代理對(duì)象
        UserService proxy = (UserService) Proxy.newProxyInstance(
                target.getClass().getClassLoader(), //類加載器
                target.getClass().getInterfaces(), //目標(biāo)實(shí)現(xiàn)的接口
                handler
        );
        //4.調(diào)用代理對(duì)象的方法
        proxy.addUser("無(wú)止境");
        proxy.deleteUser(1001);
    }

<dependency>
            <groupId>cglib</groupId>
            <artifactId>cglib</artifactId>
            <version>3.3.0</version>
        </dependency>

public class OrderService {
    //模擬創(chuàng)建訂單方法
    public void createOrder(String orderNo) {
        System.out.println("創(chuàng)建訂單，訂單號(hào)為 : " + orderNo);
    }
}

public class TransactionMethodInterceptor implements MethodInterceptor {
    /**
     *
     * @param o 目標(biāo)對(duì)象
     * @param method 目標(biāo)方法
     * @param objects 方法參數(shù)
     * @param methodProxy 方法代理對(duì)象
     * @return 方法返回值
     * @throws Throwable
     */
    @Override
    public Object intercept(Object o, Method method, Object[] objects, MethodProxy methodProxy) throws Throwable {
        //前置增強(qiáng)：開(kāi)啟事務(wù)
        System.out.println("【事務(wù)】開(kāi)啟數(shù)據(jù)事務(wù)");
        //調(diào)用目標(biāo)方法(通過(guò)methodProxy提高性能)
        Object result = methodProxy.invokeSuper(o, objects);
        //后置增強(qiáng)：提交事務(wù)
        System.out.println("【事務(wù)】提交數(shù)據(jù)事務(wù)");
        return result;
    }
}

public class CglibProxyDemo {
    public static void main(String[] args) {
        //1.創(chuàng)建Enhancer實(shí)例(CGLIB核心)
        Enhancer enhancer = new Enhancer();
        enhancer.setSuperclass(OrderService.class); //設(shè)置目標(biāo)類
        enhancer.setCallback(new TransactionMethodInterceptor()); //設(shè)置增強(qiáng)器
        //2.生成動(dòng)態(tài)代理對(duì)象
        OrderService proxy = (OrderService) enhancer.create();
        //3.調(diào)用代理對(duì)象方法
        proxy.createOrder("order_112233");
    }
}