SpringBoot基础篇AOP之高级使用技能

更多相关内容，查看: http://spring.hhui.top/前面一篇博文 190301-SpringBoot基础篇AOP之基本使用姿势小结介绍了aop的简单使用方式，在文章最后，抛出了几个问题待解决，本篇博文则将针对前面的问题，看下更多关于AOP的使用说明<!– more –>I. 高级技能1. 注解拦截方式前面一文，主要介绍的是根据正则表达式来拦截对应的方法，接下来演示下如何通过注解的方式来拦截目标方法，实现也比较简单首先创建注解@Target(ElementType.METHOD)@Retention(RetentionPolicy.RUNTIME)public @interface AnoDot {}接着在目标方法上添加注解，这里借助前面博文中工程进行说明，新建一个com.git.hui.boot.aop.demo2.AnoDemoBean，注意这个包路径，是不会被前文的AnoAspect定义的Advice拦截的，这里新建一个包路径的目的就是为了尽可能的减少干扰项@Componentpublic class AnoDemoBean { @AnoDot public String genUUID(long time) { try { System.out.println(“in genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in genUUID finally!”); } }}接下来定义对应的advice, 直接在前面的AnoAspect中添加（不知道前文的也没关系，下面贴出相关的代码类，前文的类容与本节内容无关）@Aspect@Componentpublic class AnoAspect { @Before("@annotation(AnoDot)") public void anoBefore() { System.out.println(“AnoAspect “); }}测试代码@SpringBootApplicationpublic class Application { private AnoDemoBean anoDemoBean; public Application(AnoDemoBean anoDemoBean) { this.anoDemoBean = anoDemoBean; this.anoDemoBean(); } private void anoDemoBean() { System.out.println(">>>>>>>” + anoDemoBean.genUUID(System.currentTimeMillis())); } public static void main(String[] args) { SpringApplication.run(Application.class); }}输出结果如下，在执行目标方法之前，会先执行before advice中的逻辑AnoAspect in genUUID before process!in genUUID finally!>>>>>>>3a5d749d-d94c-4fc0-a7a3-12fd97f3e1fa|15515134436442. 多个advice拦截一个方法执行时，如果有多个advice满足拦截规则，是所有的都会触发么？通过前面一篇博文知道，不同类型的advice是都可以拦截的，如果出现多个相同类型的advice呢？在前面一篇博文的基础上进行操作，我们扩展下com.git.hui.boot.aop.demo.DemoBean@Componentpublic class DemoBean { @AnoDot public String genUUID(long time) { try { System.out.println(“in genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in genUUID finally!”); } }}对应的测试切面内容如@Aspect@Componentpublic class AnoAspect { @Before(“execution(public * com.git.hui.boot.aop.demo..())”) public void doBefore(JoinPoint joinPoint) { System.out.println(“do in Aspect before method called! args: " + JSON.toJSONString(joinPoint.getArgs())); } @Pointcut(“execution(public * com.git.hui.boot.aop.demo..())”) public void point() { } @After(“point()”) public void doAfter(JoinPoint joinPoint) { System.out.println(“do in Aspect after method called! args: " + JSON.toJSONString(joinPoint.getArgs())); } /** * 执行完毕之后，通过 args指定参数；通过 returning 指定返回的结果，要求返回值类型匹配 * * @param time * @param result */ @AfterReturning(value = “point() && args(time)”, returning = “result”) public void doAfterReturning(long time, String result) { System.out.println(“do in Aspect after method return! args: " + time + " ans: " + result); } @Around(“point()”) public Object doAround(ProceedingJoinPoint joinPoint) throws Throwable { System.out.println(“do in Aspect around —— before”); Object ans = joinPoint.proceed(); System.out.println(“do in Aspect around ——- over! ans: " + ans); return ans; } @Before(“point()”) public void sameBefore() { System.out.println(“SameAspect”); } @Before("@annotation(AnoDot)”) public void anoBefore() { System.out.println(“AnoAspect”); }}测试代码如下@SpringBootApplicationpublic class Application { private DemoBean demoBean; public Application(DemoBean demoBean) { this.demoBean = demoBean; this.demoBean(); } private void demoBean() { System.out.println(">>>>> " + demoBean.genUUID(System.currentTimeMillis())); } public static void main(String[] args) { SpringApplication.run(Application.class); }}输出结果如下，所有的切面都执行了，也就是说，只要满足条件的advice，都会被拦截到do in Aspect around —— beforeAnoAspectdo in Aspect before method called! args: [1551520547268]SameAspectin genUUID before process!in genUUID finally!do in Aspect around ——- over! ans: 5f6a5616-f558-4ac9-ba4b-b4360d7dc238|1551520547268do in Aspect after method called! args: [1551520547268]do in Aspect after method return! args: 1551520547268 ans: 5f6a5616-f558-4ac9-ba4b-b4360d7dc238|1551520547268>>>>> 5f6a5616-f558-4ac9-ba4b-b4360d7dc238|15515205472683. 嵌套拦截嵌套的方式有几种case，先看第一种a. 调用方法不满足拦截规则，调用本类中其他满足拦截条件的方法这里我们借助第一节中的bean来继续模拟, 在AnoDemoBean类中，新增一个方法@Componentpublic class AnoDemoBean { public String randUUID(long time) { try { System.out.println(“in randUUID start!”); return genUUID(time); } finally { System.out.println(“in randUUID finally!”); } } @AnoDot public String genUUID(long time) { try { System.out.println(“in genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in genUUID finally!”); } }}对应的切面为@Aspect@Componentpublic class NetAspect { @Around("@annotation(AnoDot)”) public Object doAround(ProceedingJoinPoint joinPoint) throws Throwable { System.out.println(“In NetAspect doAround before!”); Object ans = joinPoint.proceed(); System.out.println(“In NetAspect doAround over! ans: " + ans); return ans; }}然后测试case需要改为直接调用 AnoDemoBean#randUUID，需要看这个方法内部调用的genUUID是否会被切面拦截住@SpringBootApplicationpublic class Application { private AnoDemoBean anoDemoBean; public Application(AnoDemoBean anoDemoBean) { this.anoDemoBean = anoDemoBean; this.anoDemoBean(); } private void anoDemoBean() { System.out.println(">>>>>>>” + anoDemoBean.randUUID(System.currentTimeMillis())); } public static void main(String[] args) { SpringApplication.run(Application.class); }}输出结果如下，没有切面的日志，表明这种场景下，不会被拦截in randUUID start!in genUUID before process!in genUUID finally!in randUUID finally!>>>>>>>0c6a5ccf-30c0-4ac0-97f2-3dc063580f3d|1551522176035b. 调用方法不满足拦截规则，调用其他类中满足拦截条件的方法依然使用前面的例子进行说明，不过是稍稍改一下AnoDemoBean，调用第二节中的DemoBean的方法DemoBean的代码如下@AnoDotpublic String genUUID(long time) { try { System.out.println(“in DemoBean genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in DemoBean genUUID finally!”); }}然后AnoDemoBean的代码如下@Componentpublic class AnoDemoBean { @Autowired private DemoBean demoBean; public String randUUID(long time) { try { System.out.println(“in AnoDemoBean randUUID start!”); return genUUID(time) + “<<<>>>” + demoBean.genUUID(time); } finally { System.out.println(“in AnoDemoBean randUUID finally!”); } } @AnoDot public String genUUID(long time) { try { System.out.println(“in AnoDemoBean genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in AnoDemoBean genUUID finally!”); } }}测试代码和前面完全一致，接下来看下输出in AnoDemoBean randUUID start!in AnoDemoBean genUUID before process!in AnoDemoBean genUUID finally!### 上面三行为 anoDemoBean#randUUID方法调用 anoDemoBean#genUUID方法的输出结果，可以看到没有切面执行的日志输出### 下面的为调用 demoBean#genUUID 方法，可以看到切面(NetAspect#doAround)执行的日志In NetAspect doAround before!in DemoBean genUUID before process!in DemoBean genUUID finally!In NetAspect doAround over! ans: f35b8878-fbd0-4840-8fbe-5fef8eda5e31|1551522532092### 最后是收尾in AnoDemoBean randUUID finally!>>>>>>>e516a35f-b85a-4cbd-aae0-fa97cdecab47|1551522532092<<<>>>f35b8878-fbd0-4840-8fbe-5fef8eda5e31|1551522532092从上面的日志分析中，可以明确看出对比，调用本类中，满足被拦截的方法，也不会走切面逻辑；调用其他类中的满足切面拦截的方法，会走切面逻辑c. 调用方法满足切面拦截条件，又调用其他满足切面拦截条件的方法这个和两个case有点像，不同的是直接调用的方法也满足被切面拦截的条件，我们主要关注点在于嵌套调用的方法，会不会进入切面逻辑，这里需要修改的地方就很少了，直接把 AnoDemoBean#randUUID方法上添加注解，然后执行即可@Componentpublic class AnoDemoBean { @Autowired private DemoBean demoBean; @AnoDot public String randUUID(long time) { try { System.out.println(“in AnoDemoBean randUUID start!”); return genUUID(time) + “<<<>>>” + demoBean.genUUID(time); } finally { System.out.println(“in AnoDemoBean randUUID finally!”); } } @AnoDot public String genUUID(long time) { try { System.out.println(“in AnoDemoBean genUUID before process!”); return UUID.randomUUID() + “|” + time; } finally { System.out.println(“in AnoDemoBean genUUID finally!”); } }}输出结果如下## 最外层的切面拦截的是 AnoDemoBean#randUUID 方法的执行In NetAspect doAround before!in AnoDemoBean randUUID start!in AnoDemoBean genUUID before process!in AnoDemoBean genUUID finally!### 从跟上面三行的输出，可以知道内部调用的 AnoDemoBean#genUUID 即便满足切面拦截规则，也不会再次走切面逻辑### 下面4行，表明其他类的方法，如果满足切面拦截规则，会进入到切面逻辑In NetAspect doAround before!in DemoBean genUUID before process!in DemoBean genUUID finally!In NetAspect doAround over! ans: d9df7388-2ef8-4b1a-acb5-6639c47f36ca|1551522969801in AnoDemoBean randUUID finally!In NetAspect doAround over! ans: cf350bc2-9a9a-4ef6-b496-c913d297c960|1551522969801<<<>>>d9df7388-2ef8-4b1a-acb5-6639c47f36ca|1551522969801>>>>>>>cf350bc2-9a9a-4ef6-b496-c913d297c960|1551522969801<<<>>>d9df7388-2ef8-4b1a-acb5-6639c47f36ca|1551522969801从输出结果进行反推，一个结论是执行的目标方法，如果调用了本类中一个满足切面规则的方法A时，在执行方法A的过程中，不会触发切面逻辑执行的目标方法，如果调用其他类中一个满足切面规则的方法B时，在执行方法B的过程中，将会触发切面逻辑4. AOP拦截方法作用域前面测试的被拦截方法都是public，那么是否表明只有public方法才能被拦截呢？从第三节基本可以看出，private方法首先淘汰出列，为啥？因为private方法正常来讲只能内部调用，而内部调用不会走切面逻辑；所以接下来需要关注的主要放在默认作用域和protected作用域@Componentpublic class ScopeDemoBean { @AnoDot String defaultRandUUID(long time) { try { System.out.println(” in ScopeDemoBean defaultRandUUID before!”); return UUID.randomUUID() + " | default | " + time; } finally { System.out.println(” in ScopeDemoBean defaultRandUUID finally!"); } } @AnoDot protected String protectedRandUUID(long time) { try { System.out.println(" in ScopeDemoBean protectedRandUUID before!"); return UUID.randomUUID() + " | protected | " + time; } finally { System.out.println(" in ScopeDemoBean protectedRandUUID finally!"); } } @AnoDot private String privateRandUUID(long time) { try { System.out.println(" in ScopeDemoBean privateRandUUID before!"); return UUID.randomUUID() + " | private | " + time; } finally { System.out.println(" in ScopeDemoBean privateRandUUID finally!"); } }}我们不直接使用这个类里面的方法，借助前面的 AnoDemoBean，下面给出了通过反射的方式来调用private方法的case@Componentpublic class AnoDemoBean { @Autowired private ScopeDemoBean scopeDemoBean; public void scopeUUID(long time) { try { System.out.println("——– default ——–"); String defaultAns = scopeDemoBean.defaultRandUUID(time); System.out.println("——– default: " + defaultAns + " ——–\n"); System.out.println("——– protected ——–"); String protectedAns = scopeDemoBean.protectedRandUUID(time); System.out.println("——– protected: " + protectedAns + " ——–\n"); System.out.println("——– private ——–"); Method method = ScopeDemoBean.class.getDeclaredMethod(“privateRandUUID”, long.class); method.setAccessible(true); String privateAns = (String) method.invoke(scopeDemoBean, time); System.out.println("——– private: " + privateAns + " ——–\n"); } catch (Exception e) { e.printStackTrace(); } }}测试case@SpringBootApplicationpublic class Application { private AnoDemoBean anoDemoBean; public Application(AnoDemoBean anoDemoBean) { this.anoDemoBean = anoDemoBean; this.anoDemoBean(); } private void anoDemoBean() { anoDemoBean.scopeUUID(System.currentTimeMillis()); } public static void main(String[] args) { SpringApplication.run(Application.class); }}输出结果如下，从日志打印来看，protected和default方法的切面都走到了——– default ——–In NetAspect doAround before! in ScopeDemoBean defaultRandUUID before! in ScopeDemoBean defaultRandUUID finally!In NetAspect doAround over! ans: 2ad7e509-c62c-4f25-b68f-eb5e0b53196d | default | 1551524311537——– default: 2ad7e509-c62c-4f25-b68f-eb5e0b53196d | default | 1551524311537 —————- protected ——–In NetAspect doAround before! in ScopeDemoBean protectedRandUUID before! in ScopeDemoBean protectedRandUUID finally!In NetAspect doAround over! ans: 9eb339f8-9e71-4321-ab83-a8953d1b8ff8 | protected | 1551524311537——– protected: 9eb339f8-9e71-4321-ab83-a8953d1b8ff8 | protected | 1551524311537 —————- private ——– in ScopeDemoBean privateRandUUID before! in ScopeDemoBean privateRandUUID finally!——– private: 1826afac-6eca-4dc3-8edc-b4ca7146ce28 | private | 1551524311537 ——–5. 小结本篇博文篇幅比较长，主要是测试代码比较占用地方，因此有必要简单的小结一下，做一个清晰的归纳，方便不想看细节，只想获取最终结论的小伙伴注解拦截方式:首先声明注解在目标方法上添加注解切面中，advice的内容形如 @Around("@annotation(AnoDot)")多advice情况：多个advice满足拦截场景时，全部都会执行嵌套场景执行的目标方法，如果调用了本类中一个满足切面规则的方法A时，在执行方法A的过程中，不会触发切面逻辑执行的目标方法，如果调用其他类中一个满足切面规则的方法B时，在执行方法B的过程中，将会触发切面逻辑作用域public, protected, default 作用域的方法都可以被拦截优先级这个内容因为特别多，所以有必要单独拎出来，其主要的分类如下同一aspect，不同advice的执行顺序不同aspect，advice的执行顺序同一aspect，相同advice的执行顺序II. 其他0. 项目工程：https://github.com/liuyueyi/spring-boot-demo项目: https://github.com/liuyueyi/spring-boot-demo/tree/master/spring-boot/010-aop1. 一灰灰Blog一灰灰Blog个人博客 https://blog.hhui.top一灰灰Blog-Spring专题博客 http://spring.hhui.top一灰灰的个人博客，记录所有学习和工作中的博文，欢迎大家前去逛逛2. 声明尽信书则不如，以上内容，纯属一家之言，因个人能力有限，难免有疏漏和错误之处，如发现bug或者有更好的建议，欢迎批评指正，不吝感激微博地址: 小灰灰BlogQQ：一灰灰/33027978403. 扫描关注一灰灰blog知识星球