面試官:Spring 注解 @After,@Around,@Before 的執(zhí)行順序是?
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@Before,@After,@Around,@AfterRunning注解等等。@Aspect
@Component
public class LogApsect {
private static final Logger logger = LoggerFactory.getLogger(LogApsect.class);
ThreadLocal<Long> startTime = new ThreadLocal<>();
// 第一個(gè)*代表返回類型不限
// 第二個(gè)*代表所有類
// 第三個(gè)*代表所有方法
// (..) 代表參數(shù)不限
@Pointcut("execution(public * com.lmx.blog.controller.*.*(..))")
@Order(2)
public void pointCut(){};
@Pointcut("@annotation(com.lmx.blog.annotation.RedisCache)")
@Order(1) // Order 代表優(yōu)先級(jí),數(shù)字越小優(yōu)先級(jí)越高
public void annoationPoint(){};
@Before(value = "annoationPoint() || pointCut()")
public void before(JoinPoint joinPoint){
System.out.println("方法執(zhí)行前執(zhí)行......before");
ServletRequestAttributes attributes = (ServletRequestAttributes) RequestContextHolder.getRequestAttributes();
HttpServletRequest request = attributes.getRequest();
logger.info("<=====================================================");
logger.info("請(qǐng)求來(lái)源: =》" + request.getRemoteAddr());
logger.info("請(qǐng)求URL:" + request.getRequestURL().toString());
logger.info("請(qǐng)求方式:" + request.getMethod());
logger.info("響應(yīng)方法:" + joinPoint.getSignature().getDeclaringTypeName() + "." + joinPoint.getSignature().getName());
logger.info("請(qǐng)求參數(shù):" + Arrays.toString(joinPoint.getArgs()));
logger.info("------------------------------------------------------");
startTime.set(System.currentTimeMillis());
}
// 定義需要匹配的切點(diǎn)表達(dá)式,同時(shí)需要匹配參數(shù)
@Around("pointCut() && args(arg)")
public Response around(ProceedingJoinPoint pjp,String arg) throws Throwable{
System.out.println("name:" + arg);
System.out.println("方法環(huán)繞start...around");
String result = null;
try{
result = pjp.proceed().toString() + "aop String";
System.out.println(result);
}catch (Throwable e){
e.printStackTrace();
}
System.out.println("方法環(huán)繞end...around");
return (Response) pjp.proceed();
}
@After("within(com.lmx.blog.controller.*Controller)")
public void after(){
System.out.println("方法之后執(zhí)行...after.");
}
@AfterReturning(pointcut="pointCut()",returning = "rst")
public void afterRunning(Response rst){
if(startTime.get() == null){
startTime.set(System.currentTimeMillis());
}
System.out.println("方法執(zhí)行完執(zhí)行...afterRunning");
logger.info("耗時(shí)(毫秒):" + (System.currentTimeMillis() - startTime.get()));
logger.info("返回?cái)?shù)據(jù):{}", rst);
logger.info("==========================================>");
}
@AfterThrowing("within(com.lmx.blog.controller.*Controller)")
public void afterThrowing(){
System.out.println("異常出現(xiàn)之后...afterThrowing");
}
}
@Before,@After,@Around注解的區(qū)別大家可以自行百度下。總之就是@Around可以實(shí)現(xiàn)@Before和@After的功能,并且只需要在一個(gè)方法中就可以實(shí)現(xiàn)。
首先我們來(lái)測(cè)試一個(gè)方法用于獲取數(shù)據(jù)庫(kù)一條記錄的
@RequestMapping("/achieve")
public Response achieve(){
System.out.println("方法執(zhí)行-----------");
return Response.ok(articleDetailSercice.getPrimaryKeyById(1L));
}
方法執(zhí)行前執(zhí)行......before
2018-11-23 16:31:59.795 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - <=====================================================
2018-11-23 16:31:59.795 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 請(qǐng)求來(lái)源: =》0:0:0:0:0:0:0:1
2018-11-23 16:31:59.795 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 請(qǐng)求URL:http://localhost:8888/user/achieve
2018-11-23 16:31:59.795 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 請(qǐng)求方式:GET
2018-11-23 16:31:59.795 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 響應(yīng)方法:com.lmx.blog.controller.UserController.achieve
2018-11-23 16:31:59.796 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 請(qǐng)求參數(shù):[]
2018-11-23 16:31:59.796 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - ------------------------------------------------------
方法執(zhí)行-----------
2018-11-23 16:31:59.806 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - ==> Preparing: select * from article_detail where id = ?
2018-11-23 16:31:59.806 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - ==> Preparing: select * from article_detail where id = ?
2018-11-23 16:31:59.806 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - ==> Parameters: 1(Long)
2018-11-23 16:31:59.806 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - ==> Parameters: 1(Long)
2018-11-23 16:31:59.814 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - <== Total: 1
2018-11-23 16:31:59.814 [http-nio-8888-exec-9] DEBUG c.l.b.m.A.selectPrimaryKey - <== Total: 1
方法之后執(zhí)行...after.
方法執(zhí)行完執(zhí)行...afterRunning
2018-11-23 16:31:59.824 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 耗時(shí)(毫秒):27
2018-11-23 16:31:59.824 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - 返回?cái)?shù)據(jù):com.lmx.blog.common.Response@8675ce5
2018-11-23 16:31:59.824 [http-nio-8888-exec-9] INFO c.l.blog.config.LogApsect - ==========================================>
@Around的規(guī)則,所以沒(méi)有進(jìn)行環(huán)繞通知。(PS:我定義的環(huán)繞通知意思是要符合是 controller 包下的方法并且方法必須帶有參數(shù),而上述方法沒(méi)有參數(shù),所以只走了@before和@after方法,不符合@Around的匹配邏輯)@RedisCache(type = Response.class)
@RequestMapping("/sendEmail")
public Response sendEmailToAuthor(String content){
System.out.println("測(cè)試執(zhí)行次數(shù)");
return Response.ok(true);
}
name:第二封郵件呢
方法環(huán)繞start...around
方法執(zhí)行前執(zhí)行......before
2018-11-23 16:34:55.347 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - <=====================================================
2018-11-23 16:34:55.347 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求來(lái)源: =》0:0:0:0:0:0:0:1
2018-11-23 16:34:55.347 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求URL:http://localhost:8888/user/sendEmail
2018-11-23 16:34:55.348 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求方式:GET
2018-11-23 16:34:55.348 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 響應(yīng)方法:com.lmx.blog.controller.UserController.sendEmailToAuthor
2018-11-23 16:34:55.348 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求參數(shù):[第二封郵件呢]
2018-11-23 16:34:55.348 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - ------------------------------------------------------
測(cè)試執(zhí)行次數(shù)
com.lmx.blog.common.Response@6d17f2fdaop String
方法環(huán)繞end...around
方法執(zhí)行前執(zhí)行......before
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - <=====================================================
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求來(lái)源: =》0:0:0:0:0:0:0:1
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求URL:http://localhost:8888/user/sendEmail
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求方式:GET
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 響應(yīng)方法:com.lmx.blog.controller.UserController.sendEmailToAuthor
2018-11-23 16:34:55.349 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 請(qǐng)求參數(shù):[第二封郵件呢]
2018-11-23 16:34:55.350 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - ------------------------------------------------------
測(cè)試執(zhí)行次數(shù)
方法之后執(zhí)行...after.
方法執(zhí)行完執(zhí)行...afterRunning
2018-11-23 16:34:55.350 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 耗時(shí)(毫秒):0
2018-11-23 16:34:55.350 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - 返回?cái)?shù)據(jù):com.lmx.blog.common.Response@79f85428
2018-11-23 16:34:55.350 [http-nio-8888-exec-2] INFO c.l.blog.config.LogApsect - ==========================================>
@Around 環(huán)繞通知的匹配規(guī)則,所以進(jìn)入了@Around的邏輯,但是發(fā)現(xiàn)了問(wèn)題,所有的方法都被執(zhí)行了2次,不管是切面層還是方法層。(有人估計(jì)要問(wèn)我不是用的自定義注解 @RedisCache(type = Response.class) 么。為什么會(huì)符合 @Around的匹配規(guī)則呢,這個(gè)等會(huì)在下面說(shuō))我們分析日志的打印順序可以得出,在執(zhí)行環(huán)繞方法時(shí)候,會(huì)優(yōu)先進(jìn)入 @Around下的方法。@Around的方法再貼一下代碼。
// 定義需要匹配的切點(diǎn)表達(dá)式,同時(shí)需要匹配參數(shù)
@Around("pointCut() && args(arg)")
public Response around(ProceedingJoinPoint pjp,String arg) throws Throwable{
System.out.println("name:" + arg);
System.out.println("方法環(huán)繞start...around");
String result = null;
try{
result = pjp.proceed().toString() + "aop String";
System.out.println(result);
}catch (Throwable e){
e.printStackTrace();
}
System.out.println("方法環(huán)繞end...around");
return (Response) pjp.proceed();
}
@Before方法,是因?yàn)橹型居|發(fā)了 ProceedingJoinPoint.proceed() 方法。這個(gè)方法的作用是執(zhí)行被代理的方法,也就是說(shuō)執(zhí)行了這個(gè)方法之后會(huì)執(zhí)行我們controller的方法,而后執(zhí)行 @before,@after,然后回到@Around執(zhí)行未執(zhí)行的方法,最后執(zhí)行 @afterRunning,如果有異常拋出能執(zhí)行 @AfterThrowing
也就是說(shuō)環(huán)繞的執(zhí)行順序是 @Around→@Before→@After→@Around執(zhí)行 ProceedingJoinPoint.proceed() 之后的操作→@AfterRunning(如果有異?!?code style="margin: 3px;padding: 3px;outline: 0px;max-width: 100%;box-sizing: border-box !important;overflow-wrap: break-word !important;font-size: 14px;border-radius: 4px;font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(155, 110, 35);background-color: rgb(255, 245, 227);">@AfterThrowing)
而我們上述的日志相當(dāng)于把上述結(jié)果執(zhí)行了2遍,根本原因在于 ProceedingJoinPoint.proceed() 這個(gè)方法,可以發(fā)現(xiàn)在@Around 方法中我們使用了2次這個(gè)方法,然而每次調(diào)用這個(gè)方法時(shí)都會(huì)走一次@Before→@After→@Around執(zhí)行 ProceedingJoinPoint.proceed() 之后的操作→@AfterRunning(如果有異?!?code style="margin: 3px;padding: 3px;outline: 0px;max-width: 100%;box-sizing: border-box !important;overflow-wrap: break-word !important;font-size: 14px;border-radius: 4px;font-family: "Operator Mono", Consolas, Monaco, Menlo, monospace;word-break: break-all;color: rgb(155, 110, 35);background-color: rgb(255, 245, 227);">@AfterThrowing)。
因此問(wèn)題是出現(xiàn)在這里。所以更改@Around部分的代碼即可解決該問(wèn)題。更改之后的代碼如下:搜索公眾號(hào)互聯(lián)網(wǎng)架構(gòu)師復(fù)“2T”,送你一份驚喜禮包。
@Around("pointCut() && args(arg)")
public Response around(ProceedingJoinPoint pjp,String arg) throws Throwable{
System.out.println("name:" + arg);
System.out.println("方法環(huán)繞start...around");
String result = null;
Object object = pjp.proceed();
try{
result = object.toString() + "aop String";
System.out.println(result);
}catch (Throwable e){
e.printStackTrace();
}
System.out.println("方法環(huán)繞end...around");
return (Response) object;
}
name:第二封郵件呢
方法環(huán)繞start...around
方法執(zhí)行前執(zhí)行......before
2018-11-23 16:52:14.315 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - <=====================================================
2018-11-23 16:52:14.315 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 請(qǐng)求來(lái)源: =》0:0:0:0:0:0:0:1
2018-11-23 16:52:14.315 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 請(qǐng)求URL:http://localhost:8888/user/sendEmail
2018-11-23 16:52:14.315 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 請(qǐng)求方式:GET
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 響應(yīng)方法:com.lmx.blog.controller.UserController.sendEmailToAuthor
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 請(qǐng)求參數(shù):[第二封郵件呢]
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - ------------------------------------------------------
測(cè)試執(zhí)行次數(shù)
com.lmx.blog.common.Response@1b1c76afaop String
方法環(huán)繞end...around
方法之后執(zhí)行...after.
方法執(zhí)行完執(zhí)行...afterRunning
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 耗時(shí)(毫秒):0
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - 返回?cái)?shù)據(jù):com.lmx.blog.common.Response@1b1c76af
2018-11-23 16:52:14.316 [http-nio-8888-exec-4] INFO c.l.blog.config.LogApsect - ==========================================>
因?yàn)槲覀兊姆椒ㄈ匀辉赾ontroller下,因此滿足該需求,如果我們定義了controller包下的某個(gè)controller才有用。
例如:
@Pointcut("execution(public * com.lmx.blog.controller.UserController.*(..))")
@Around方法的匹配規(guī)則了,也不符合@before和@after的注解規(guī)則,因此不會(huì)匹配任何一個(gè)規(guī)則,如果需要匹配特定的方法,可以用自定義的注解形式或者特性controller下的方法①:特性的注解形式
@Pointcut("@annotation(com.lmx.blog.annotation.RedisCache)")
@Order(1) // Order 代表優(yōu)先級(jí),數(shù)字越小優(yōu)先級(jí)越高
public void annoationPoint(){};
@RedisCache注解,在@Before,@After,@Around等方法上添加該切點(diǎn)的方法名(“annoationPoint()”),如果有多個(gè)注解需要匹配則用 || 隔開(kāi)②:指定controller或者指定controller下的方法
@Pointcut("execution(public * com.lmx.blog.controller.UserController.*(..))")
@Order(2)
public void pointCut(){};
com.lmx.blog.controller包下的UserController下的所有方法。另外,Spring 系列面試題和答案全部整理好了,微信搜索互聯(lián)網(wǎng)架構(gòu)師,在后臺(tái)發(fā)送:面試,可以在線閱讀。第一個(gè)*代表的是返回類型不限
*代表的是該controller下的所有方法,(..)代表的是參數(shù)不限總結(jié)
當(dāng)方法符合切點(diǎn)規(guī)則不符合環(huán)繞通知的規(guī)則時(shí)候,執(zhí)行的順序如下
@Before→@After→@AfterRunning(如果有異常→@AfterThrowing)
當(dāng)方法符合切點(diǎn)規(guī)則并且符合環(huán)繞通知的規(guī)則時(shí)候,執(zhí)行的順序如下
原文鏈接:https://blog.csdn.net/lmx125254/article/details/84398412
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