SpringAOP不僅可以實(shí)現(xiàn)在不產(chǎn)生新類的情況下打印日志，還可以管理事務(wù)、緩存等。具體可以了解官方文檔。https://docs.spring.io/spring/docs/current/spring-framework-reference/core.html#aop-api

在使用SpringAOP，這里還是先簡(jiǎn)單講解一些基本的知識(shí)吧，如果說(shuō)的不對(duì)請(qǐng)及時(shí)指正，這里主要是根據(jù)官方文檔來(lái)總結(jié)的。本章內(nèi)容主要涉及的知識(shí)點(diǎn)。

Pointcut: 切入點(diǎn)，這里用于定義規(guī)則，進(jìn)行方法的切入（形象的比喻就是一把刀）。

JoinPoint: 連接點(diǎn)，用于連接定義的切面。

Before: 在之前，在切入點(diǎn)方法執(zhí)行之前。

AfterReturning: 在切入點(diǎn)方法結(jié)束并返回時(shí)執(zhí)行。

這里除了SpringAOP相關(guān)的知識(shí)，還涉及到了線程相關(guān)的知識(shí)點(diǎn)，因?yàn)槲覀冃枰紤]多線程中它們各自需要保存自己的變量，所以就用到了ThreadLocal。

這里主要是用到aop和mongodb，在pom.xml文件中加入以下依賴即可:

    org.springframework.boot
    spring-boot-starter-aop


    org.springframework.boot
    spring-boot-starter-data-mongodb

/**
 * 請(qǐng)求日志實(shí)體，用于保存請(qǐng)求日志
 */
@Document
class WebLog {
    var id: String = ""
    var request: String? = null
    var response: String? = null
    var time: Long? = null
    var requestUrl: String? = null
    var requestIp: String? = null
    var startTime: Long? = null
    var endTime: Long? = null
    var method: String? = null

    override fun toString(): String {
        return ObjectMapper().writeValueAsString(this)
    }
}

/**
 * 業(yè)務(wù)對(duì)象，上一章講JPA中有定義
 */
@Document
class Student {
    @Id
    var id :String? = null
    var name :String? = null
    var age :Int? = 0
    var gender :String? = null
    var sclass :String ?= null

    override fun toString(): String {
        return ObjectMapper().writeValueAsString(this)
    }
}

/**
 * 定義一個(gè)切入，只要是為io.intodream..web下public修飾的方法都要切入
 */
@Pointcut(value = "execution(public * io.intodream..web.*.*(..))")
fun webLog() {}

定義切入點(diǎn)的表達(dá)式還可以使用within、如:

/**
 * 表示在io.intodream.web包下的方法都會(huì)被切入
 */
@Pointcut(value = "within(io.intodream.web..*")

/**
 * 切面的連接點(diǎn)，并聲明在該連接點(diǎn)進(jìn)入之前需要做的一些事情
 */
@Before(value = "webLog()")
@Throws(Throwable::class)
fun doBefore(joinPoint: JoinPoint) {
    val webLog = WebLog()
    webLog.startTime = System.currentTimeMillis()
    val attributes = RequestContextHolder.getRequestAttributes() as ServletRequestAttributes?
    val request = attributes!!.request
    val args = joinPoint.args
    val paramNames = (joinPoint.signature as CodeSignature).parameterNames
    val params = HashMap(args.size)
    for (i in args.indices) {
        if (args[i] !is BindingResult) {
            params[paramNames[i]] = args[i]
        }
    }
    webLog.id = UUID.randomUUID().toString()
    webLog.request = params.toString()
    webLog.requestUrl = request.requestURI.toString()
    webLog.requestIp = request.remoteAddr
    webLog.method = request.method
    webRequestLog.set(webLog)
    logger.info("REQUEST={} {}; SOURCE IP={}; ARGS={}", request.method,
            request.requestURL.toString(), request.remoteAddr, params)
}

@AfterReturning(returning = "ret", pointcut = "webLog()")
@Throws(Throwable::class)
fun doAfterReturning(ret: Any) {
    val webLog = webRequestLog.get()
    webLog.response = ret.toString()
    webLog.endTime = System.currentTimeMillis()
    webLog.time = webLog.endTime!! - webLog.startTime!!
    logger.info("RESPONSE={}; SPEND TIME={}MS", ObjectMapper().writeValueAsString(ret), webLog.time)
    logger.info("webLog:{}", webLog)
    webLogRepository.save(webLog)
    webRequestLog.remove()
}

這里的主要思路是，在方法執(zhí)行前，先記錄詳情的請(qǐng)求參數(shù)，請(qǐng)求方法，請(qǐng)求ip， 請(qǐng)求方式及進(jìn)入時(shí)間，然后將對(duì)象放入到ThreadLocal中，在方法結(jié)束后并取到對(duì)應(yīng)的返回對(duì)象且計(jì)算出請(qǐng)求耗時(shí)，然后將請(qǐng)求日志保存到mongodb中。

完成的代碼

package io.intodream.kotlin07.aspect

import com.fasterxml.jackson.databind.ObjectMapper
import io.intodream.kotlin07.dao.WebLogRepository
import io.intodream.kotlin07.entity.WebLog
import org.aspectj.lang.JoinPoint
import org.aspectj.lang.annotation.AfterReturning
import org.aspectj.lang.annotation.Aspect
import org.aspectj.lang.annotation.Before
import org.aspectj.lang.annotation.Pointcut
import org.aspectj.lang.reflect.CodeSignature
import org.slf4j.Logger
import org.slf4j.LoggerFactory
import org.springframework.beans.factory.annotation.Autowired
import org.springframework.core.annotation.Order
import org.springframework.stereotype.Component
import org.springframework.validation.BindingResult
import org.springframework.web.context.request.RequestContextHolder
import org.springframework.web.context.request.ServletRequestAttributes
import java.util.*

/**
 * {描述}
 *
 * @author yangxianxi@gogpay.cn
 * @date 2019/4/10 19:06
 *
 */
@Aspect
@Order(5)
@Component
class WebLogAspect {

    private val logger:Logger = LoggerFactory.getLogger(WebLogAspect::class.java)

    private val webRequestLog: ThreadLocal = ThreadLocal()

    @Autowired lateinit var webLogRepository: WebLogRepository

    /**
     * 定義一個(gè)切入，只要是為io.intodream..web下public修飾的方法都要切入
     */
    @Pointcut(value = "execution(public * io.intodream..web.*.*(..))")
    fun webLog() {}

    /**
     * 切面的連接點(diǎn)，并聲明在該連接點(diǎn)進(jìn)入之前需要做的一些事情
     */
    @Before(value = "webLog()")
    @Throws(Throwable::class)
    fun doBefore(joinPoint: JoinPoint) {
        val webLog = WebLog()
        webLog.startTime = System.currentTimeMillis()
        val attributes = RequestContextHolder.getRequestAttributes() as ServletRequestAttributes?
        val request = attributes!!.request
        val args = joinPoint.args
        val paramNames = (joinPoint.signature as CodeSignature).parameterNames
        val params = HashMap(args.size)
        for (i in args.indices) {
            if (args[i] !is BindingResult) {
                params[paramNames[i]] = args[i]
            }
        }
        webLog.id = UUID.randomUUID().toString()
        webLog.request = params.toString()
        webLog.requestUrl = request.requestURI.toString()
        webLog.requestIp = request.remoteAddr
        webLog.method = request.method
        webRequestLog.set(webLog)
        logger.info("REQUEST={} {}; SOURCE IP={}; ARGS={}", request.method,
                request.requestURL.toString(), request.remoteAddr, params)
    }

    @AfterReturning(returning = "ret", pointcut = "webLog()")
    @Throws(Throwable::class)
    fun doAfterReturning(ret: Any) {
        val webLog = webRequestLog.get()
        webLog.response = ret.toString()
        webLog.endTime = System.currentTimeMillis()
        webLog.time = webLog.endTime!! - webLog.startTime!!
        logger.info("RESPONSE={}; SPEND TIME={}MS", ObjectMapper().writeValueAsString(ret), webLog.time)
        logger.info("webLog:{}", webLog)
        webLogRepository.save(webLog)
        webRequestLog.remove()
    }
}

這里定義的是Web層的切面，對(duì)于Service層我也可以定義一個(gè)切面，但是對(duì)于Service層的進(jìn)入和返回的日志我們可以把級(jí)別稍等調(diào)低一點(diǎn)，這里改debug,具體實(shí)現(xiàn)如下：

package io.intodream.kotlin07.aspect

import com.fasterxml.jackson.databind.ObjectMapper
import org.aspectj.lang.JoinPoint
import org.aspectj.lang.annotation.AfterReturning
import org.aspectj.lang.annotation.Aspect
import org.aspectj.lang.annotation.Before
import org.aspectj.lang.annotation.Pointcut
import org.aspectj.lang.reflect.CodeSignature
import org.slf4j.Logger
import org.slf4j.LoggerFactory
import org.springframework.core.annotation.Order
import org.springframework.stereotype.Component
import org.springframework.validation.BindingResult

/**
 * service層所有public修飾的方法調(diào)用返回日志
 *
 * @author yangxianxi@gogpay.cn
 * @date 2019/4/10 17:33
 *
 */
@Aspect
@Order(2)
@Component
class ServiceLogAspect {

    private val logger: Logger = LoggerFactory.getLogger(ServiceLogAspect::class.java)

    /**
     *
     */
    @Pointcut(value = "execution(public * io.intodream..service.*.*(..))")
    private fun serviceLog(){}

    @Before(value = "serviceLog()")
    fun deBefore(joinPoint: JoinPoint) {
        val args = joinPoint.args
        val codeSignature = joinPoint.signature as CodeSignature
        val paramNames = codeSignature.parameterNames
        val params = HashMap(args.size).toMutableMap()
        for (i in args.indices) {
            if (args[i] !is BindingResult) {
                params[paramNames[i]] = args[i]
            }
        }
        logger.debug("CALL={}; ARGS={}", joinPoint.signature.name, params)
    }

    @AfterReturning(returning = "ret", pointcut = "serviceLog()")
    @Throws(Throwable::class)
    fun doAfterReturning(ret: Any) {
        logger.debug("RESPONSE={}", ObjectMapper().writeValueAsString(ret))
    }
}

這里就不在貼出Service層和web的代碼實(shí)現(xiàn)了，因?yàn)槲沂强截愔皩PA那一章的代碼，唯一不同的就是加入了切面，切面的加入并不影響原來(lái)的業(yè)務(wù)流程。

執(zhí)行如下請(qǐng)求:

我們會(huì)在控制臺(tái)看到如下日志

2019-04-14 19:32:27.208  INFO 4914 --- [nio-9000-exec-1] i.i.kotlin07.aspect.WebLogAspect         : REQUEST=POST http://localhost:9000/api/student/; SOURCE IP=0:0:0:0:0:0:0:1; ARGS={student={"id":"5","name":"Rose","age":17,"gender":"Girl","sclass":"Second class"}}
2019-04-14 19:32:27.415  INFO 4914 --- [nio-9000-exec-1] org.mongodb.driver.connection            : Opened connection [connectionId{localValue:2, serverValue:4}] to localhost:27017
2019-04-14 19:32:27.431  INFO 4914 --- [nio-9000-exec-1] i.i.kotlin07.aspect.WebLogAspect         : RESPONSE={"id":"5","name":"Rose","age":17,"gender":"Girl","sclass":"Second class"}; SPEND TIME=239MS
2019-04-14 19:32:27.431  INFO 4914 --- [nio-9000-exec-1] i.i.kotlin07.aspect.WebLogAspect         : webLog:{"id":"e7b0ca1b-0a71-4fa0-9f5f-95a29d4d54a1","request":"{student={"id":"5","name":"Rose","age":17,"gender":"Girl","sclass":"Second class"}}","response":"{"id":"5","name":"Rose","age":17,"gender":"Girl","sclass":"Second class"}","time":239,"requestUrl":"/api/student/","requestIp":"0:0:0:0:0:0:0:1","startTime":1555241547191,"endTime":1555241547430,"method":"POST"}

查看數(shù)據(jù)庫(kù)會(huì)看到我們的請(qǐng)求日志已經(jīng)寫入了:

這里有一個(gè)地方需要注意，在Service層的實(shí)現(xiàn)，具體如下:

return studentRepository.findById(id).get()

這里的findById會(huì)返回一個(gè)Optional對(duì)象，如果沒(méi)有查到數(shù)據(jù)，我們使用get獲取數(shù)據(jù)會(huì)出現(xiàn)異常java.util.NoSuchElementException: No value present，可以改為返回對(duì)象可以為空只要在返回類型后面加一個(gè)?即可，同時(shí)調(diào)用Optional的ifPresent進(jìn)行安全操作。