Day22SSM之Spring AOP***

Spring AOP concept

• (1) AOP (Aspect Oriented Programming) is 面向切面编程.
  It is a technology that realizes the unified maintenance of program functions through pre-compilation and runtime dynamic agents.
  To put it simply, the function enhancement of the method is
  essentially generated without changing the original code of the method.一个新的类，叫做代理类
• (2) AOP adopts a dynamic proxy method for program expansion. ( JDK动态代理and Cglib动态代理two methods)
  
  

Spring dynamic proxy

• (1) JDK dynamic proxy
  "methods of the
  Proxy class" static methods of the Proxy class can create proxy objects
  static Object newProxyInstance(ClassLoader loader, Class<?>[] interfaces, InvocationHandler h)
  " three parameters
  Parameter 1: ClassLoader loader class loader, used to load the proxy object
  Parameters 2: Class<?>[] interfaces target The bytecode object array of the class. Because the proxy is an interface, you need to know all the methods in the interface.
  Parameter 3: InvocationHandler h execution handle, the core logic of proxy object processing is in this interface
• (2) Case: CEOs eat,
  CEOs,
  secretary

TestJdkProxy

public class TestJdkProxy {
    
    
    public static void main(String[] args) {
    
    
        //Jdk代理
        //ILaoZong
        LaoZong laoZong = new LaoZong();
        MiShu miShu = new MiShu();
        //1 创建一个代理类，创建该类的对象
        ClassLoader classLoader = LaoZong.class.getClassLoader();
        Class[] interfaces= new Class[]{
    
    ILaoZong.class};
        //处理器
        InvocationHandler handler = new InvocationHandler() {
    
    
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    
    
                //调 laibeijiu()
                miShu.laiBeiJiu();
                //调 eat()
                //laoZong.eat();
                //method 被增加的方法
                Object returnValue = method.invoke(laoZong,args);
                //调 laiGenYan()
                miShu.laiGenYan();
                return returnValue;
            }
        };
        ILaoZong iLaoZong = (ILaoZong) Proxy.newProxyInstance(classLoader,interfaces,handler);
        iLaoZong.eat();
    }
}

LaoZong

public class LaoZong implements ILaoZong{
    
    
    public void eat(){
    
    
        System.out.println("eat san xia guo");
        System.out.println("eat wa wa cai");
    }
}

ILaoZong

public interface ILaoZong {
    
    
    void eat();
}

MiShu

public class MiShu {
    
    
    public void laiBeiJiu(){
    
    
        System.out.println("laiBeiJiu");
    }
    public void laiGenYan(){
    
    
        System.out.println("laiGenYan");
    }
}

Case: Log System

Add log to all methods of a class

Demo02

public class Demo02 {
    
    
    public static void main(String[] args) {
    
    
        Person p = new Person("jack","123456");
        //生成代理类，创建该类对象
        PersonDao2 personDao2 = new PersonDao2();
        Logger logger = LoggerFactory.getLogger(PersonDao2.class);
        ClassLoader classLoader=PersonDao2.class.getClassLoader();//与原来类一样
        Class<?>[] interfaces=PersonDao2.class.getInterfaces();//与原来类一样
        InvocationHandler handler = new InvocationHandler() {
    
    
            @Override
            public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
    
    
//                调用Dao类的update(person)
//                调用Logger类的debug(“update  parameter return”)
                //update delete add 的执行
                //开始
                long start = System.currentTimeMillis();
                Object returnVal = method.invoke(personDao2,args);
                long time = System.currentTimeMillis()-start;
                logger.debug("方法名:"+method.getName()+" 参数"+ Arrays.toString(args)+" 返回值:"+returnVal+" 耗时"+time);
                return returnVal;
            }
        };
        IPersonDao2 personDao= (IPersonDao2) Proxy.newProxyInstance(classLoader,interfaces,handler);
 //       personDao.add(p);
        personDao.update(p);
//        personDao.delete(1);
    }
}

PersonDao2

public class PersonDao2 implements IPersonDao2{
    
    

    public void add(Person p){
    
    
        System.out.println("执行 数据库的insert");
    }
    public void update(Person p){
    
    
        System.out.println("执行 数据库的update");
        try {
    
    
            Thread.sleep(3000);
        } catch (InterruptedException e) {
    
    
            e.printStackTrace();
        }
    }
    public void delete(int id){
    
    
        System.out.println("执行 数据库的delete");
    }
}

IPersonDao2

public interface IPersonDao2 {
    
    
     void add(Person p);
     void update(Person p);
     void delete(int id);
}