AOP的作用：

日誌的記錄

許可權的校驗

效能的檢測（檢視某個方法執行了多長時間）

事務的管理

AOP這種思想是由AOP聯盟組織提出來的一種思想，spring是把這種思想實現的最好的框架之一

Aop的兩種實現方式：

Jdk的動態代理：只能對有介面的實現類進行增強

Cglib的動態代理：可以對類進行增強，這個類不需要實現任何介面

第一步：建立maven工程，解決兩個問題

第二步：匯入jar包

<dependencies>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-context -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-context</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-core -->

<dependency>

<groupId>org.springframework

<artifactId>spring-core</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-beans -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-beans

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-expression -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-expression</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-web -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-web</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/javax.servlet/javax.servlet-api -->

<dependency>

<groupId>javax.servlet</groupId>

<artifactId>javax.servlet-api</artifactId>

<version>3.1.0</version>

<scope>provided</scope>

</dependency>

<!-- https://mvnrepository.com/artifact/junit/junit -->

<dependency>

<groupId>junit</groupId>

<artifactId>junit</artifactId>

<version>4.11</version>

<scope>test</scope>

</dependency>

<!-- spring的註解開發必須要依賴的jar包 -->

<!-- https://mvnrepository.com/artifact/org.springframework/spring-aop -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-aop</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-test -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-test</artifactId>

<version>4.2.4.RELEASE</version>

<scope>test</scope>

</dependency>

<!-- https://mvnrepository.com/artifact/aopalliance/aopalliance -->

<dependency>

<groupId>aopalliance</groupId>

<artifactId>aopalliance</artifactId>

<version>1.0</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.aspectj/aspectjweaver -->

<dependency>

<groupId>org.aspectj</groupId>

<artifactId>aspectjweaver</artifactId>

<version>1.6.8</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-aop -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-aop</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

<!-- https://mvnrepository.com/artifact/org.springframework/spring-aspects -->

<dependency>

<groupId>org.springframework</groupId>

<artifactId>spring-aspects</artifactId>

<version>4.2.4.RELEASE</version>

</dependency>

</dependencies>

<build>

<plugins>

<plugin>

<groupId>org.apache.maven.plugins</groupId>

<artifactId>maven-compiler-plugin</artifactId>

<version>3.1</version>

<configuration>

<source>1.8</source>

<target>1.8</target>

<encoding>utf-8</encoding>

</configuration>

</plugin>

</plugins>

</build>

第一種方式：通過jdk的動態代理實現增強的功能

定義介面與實現類

定義我們的增強類

實現我們的代理類

public class PersonProxy implements InvocationHandler{

private  PersonDao personDao;

public  PersonProxy(PersonDao personDao){

this.personDao = personDao;

}

public  PersonDao createPersonDaoProxy(){

/**

 * 第一個引數：類載入器

 * 第二個引數：所有實現的介面

 * 第三個引數：invocationHandler

 *

 */

PersonDao newProxyInstance = (PersonDao) Proxy.newProxyInstance(personDao.getClass().getClassLoader(), personDao.getClass().getInterfaces(), this);

return newProxyInstance;

}

/**

 * 實現了invocationHandler介面之後就必須要實現一個方法，叫做invoke方法

 */

@Override

public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {

if(method.getName().equals("add")){

PersonStrong strong = new PersonStrong();

strong.checkPrivilege();

return  method.invoke(personDao, args);

}

return  method.invoke(personDao, args);

}

}

測試用例

/**

 *

 * @throws Exception

 */

@Test

publicvoid getJdkProxy() throws Exception {

//介面指向實現類，多型

PersonDao dao = new  PersonDaoImpl();

PersonProxyproxy = newPersonProxy(dao);

PersonDao createPersonDaoProxy = proxy.createPersonDaoProxy();

createPersonDaoProxy.add();

}