169 lines
4.5 KiB
Markdown
169 lines
4.5 KiB
Markdown
# spring AOP（注解方式）
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## 一、说明
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### 1.1 项目结构说明
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1. 切面配置位于com.heibaiying.config下AopConfig.java文件；
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2. 自定义切面位于advice下，其中CustomAdvice是标准的自定义切面，FirstAdvice和SecondAdvice用于测试多切面共同作用于同一个被切入点时的执行顺序；
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3. OrderService是待切入方法。
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### 1.2 依赖说明
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除了spring的基本依赖外，需要导入aop依赖包
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```xml
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<!--aop 相关依赖-->
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<dependency>
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<groupId>org.springframework</groupId>
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<artifactId>spring-aop</artifactId>
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<version>${spring-base-version}</version>
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</dependency>
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```
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## 二、spring aop
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#### 2.1 创建待切入接口及其实现类
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```java
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public interface OrderService {
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Order queryOrder(Long id);
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Order createOrder(Long id, String productName);
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}
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```
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```java
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public class OrderServiceImpl implements OrderService {
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public Order queryOrder(Long id) {
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return new Order(id, "product", new Date());
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}
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public Order createOrder(Long id, String productName) {
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// 模拟抛出异常
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// int j = 1 / 0;
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return new Order(id, "new Product", new Date());
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}
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}
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```
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#### 2.2 创建自定义切面类
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注：@Pointcut的值可以是多个切面表达式的组合。
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```java
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/**
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* @author : heibaiying
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* @description : 自定义切面
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*/
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@Aspect
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@Component //除了加上@Aspect外 还需要声明为spring的组件 @Aspect只是一个切面声明
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public class CustomAdvice {
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/**
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* 使用 || , or 表示或
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* 使用 && , and 表示与
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* ! 表示非
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*/
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@Pointcut("execution(* com.heibaiying.service.OrderService.*(..)) && !execution(* com.heibaiying.service.OrderService.deleteOrder(..))")
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private void pointCut() {
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}
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@Before("pointCut()")
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public void before(JoinPoint joinPoint) {
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//获取节点名称
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String name = joinPoint.getSignature().getName();
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Object[] args = joinPoint.getArgs();
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System.out.println(name + "方法调用前：获取调用参数" + Arrays.toString(args));
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}
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// returning 参数用于指定返回结果与哪一个参数绑定
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@AfterReturning(pointcut = "pointCut()", returning = "result")
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public void afterReturning(JoinPoint joinPoint, Object result) {
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System.out.println("后置返回通知结果" + result);
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}
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@Around("pointCut()")
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public Object around(ProceedingJoinPoint joinPoint) throws Throwable {
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System.out.println("环绕通知-前");
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//调用目标方法
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Object proceed = joinPoint.proceed();
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System.out.println("环绕通知-后");
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return proceed;
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}
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// throwing 参数用于指定抛出的异常与哪一个参数绑定
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@AfterThrowing(pointcut = "pointCut()", throwing = "exception")
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public void afterThrowing(JoinPoint joinPoint, Exception exception) {
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System.err.println("后置异常通知:" + exception);
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}
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@After("pointCut()")
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public void after(JoinPoint joinPoint) {
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System.out.println("后置通知");
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}
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}
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```
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#### 2.3 配置切面
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```java
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/**
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* @author : heibaiying
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* @description : 开启切面配置
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*/
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@Configuration
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@ComponentScan("com.heibaiying.*")
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@EnableAspectJAutoProxy // 开启@Aspect注解支持 等价于<aop:aspectj-autoproxy>
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public class AopConfig {
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}
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```
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#### 2.4 测试切面
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```java
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@RunWith(SpringRunner.class)
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@ContextConfiguration(classes = AopConfig.class)
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public class AopTest {
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@Autowired
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private OrderService orderService;
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@Test
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public void saveAndQuery() {
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orderService.createOrder(1283929319L, "手机");
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orderService.queryOrder(4891894129L);
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}
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/**
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* 多个切面作用于同一个切入点时，可以用@Order指定切面的执行顺序
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* 优先级高的切面在切入方法前执行的通知(before)会优先执行，但是位于方法后执行的通知(after,afterReturning)反而会延后执行
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*/
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@Test
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public void delete() {
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orderService.deleteOrder(12793179L);
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}
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}
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```
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#### 2.5 切面执行顺序
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- 多个切面作用于同一个切入点时，可以用@Order指定切面的执行顺序
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- 优先级高的切面在切入方法前执行的通知(before)会优先执行，但是位于方法后执行的通知(after,afterReturning)反而会延后执行，类似于同心圆原理。
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