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利用AOP重构代码

發(fā)布時間：2025/3/15 编程问答 29 豆豆

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????? AOP是什么？

　　??? AOP是OOP的延續(xù)，Aspect Oriented Programming的縮寫，即面向方面編程。AOP是GoF設計模式的延續(xù)，設計模式追求的是調(diào)用者和被調(diào)用者之間的解耦，AOP也是這種目標的一種實現(xiàn)。

??????案例:在應用程序中,我們經(jīng)常會對某一段程序做異常處理,或者是把一個方法的調(diào)用所消耗的時間體現(xiàn)在日志中,如果我們對每個方法都寫具體的實現(xiàn),我想并不是一件輕松的事情。對于異常處理來講，其實我們平常編程很少去捕獲具體的異常，當然特殊程序除外，例如客戶端捕獲WCF異常時最好捕獲CommunicationException，TimeoutException，Exception。否則一般都會直接捕獲Exception，因為很多異常往往是意料之外的異常。對于記錄方法調(diào)用時間問題，我想也非常麻煩，下面例子簡單的展示了記錄時間：當你需要對多個方法都需要記錄時間時，這些代碼往往讓人感覺有重構(gòu)的必要。

???

Stopwatch?sw?=?new?Stopwatch();
???sw.Start();
???//方法執(zhí)行.....
???sw.Stop();
???WebLog.SquareLog.CommonLogger.Error("取積分廣場首頁酒店數(shù)據(jù)用時:"+sw.ElapsedMilliseconds?.ToString?()+"毫秒");

??? ? 上面的記錄方法調(diào)用用時，如果抽象出來，其實有下列特性：
????? 1:不是具體訪問類的首要或主要功能，訪問類主要功能是業(yè)務邏輯處理。
????? 2：具體訪問類的主要功能可以獨立、區(qū)分開來的。
????? 3：是這個系統(tǒng)的一個縱向切面，涉及多個類、多個類的方法。示意圖如下：
?
?????

????? aspect:? 新的程序結(jié)構(gòu)關注系統(tǒng)的縱向切面，例如這里的異常處理以及方法調(diào)用時間記錄，這個新的程序結(jié)構(gòu)就是aspect（方面）,方面（aspect）應該有以下職責：提供一些必備的功能，對被訪問對象實現(xiàn)特有功能,以保證所以方法在被執(zhí)行時都能正常的執(zhí)行異常處理或者是其它的功能。

???? ?AOP應用范圍
????? 1：Authentication 權(quán)限
???? ?2：Error handling 錯誤處理
????? 3：logging, tracing, profiling and monitoring　記錄跟蹤　優(yōu)化　校準
??? ??......

???? AOP具體實現(xiàn)：主要是利用泛型委托來實現(xiàn)AOP思想。但泛型委托有一個局限就是最多支持四個參數(shù)，當你的方法超過四個時就不太好應用AOP重構(gòu)了。我最近分析了有以下三個地方我們可以對代碼進行優(yōu)化：

???? 第一：普通方法異常處理：ErrorHandler類,實現(xiàn)類參考第二或者是第三。

??????????? 客戶端調(diào)用：
?????????

代碼 string?ErrorMethodText="取積分廣場首頁酒店數(shù)據(jù)異常:";
???????????list?=?ErrorWCFHandler?.Invoke<ISearchHotelForSquare,?List<HotelGenericInfo>>(cli,?proxy?=>?proxy.GetHotelGenericListForSquare(requestInfo).ToList()?);?

?
???? 第二：客戶端調(diào)用WCF的異常處理：ErrorWCFHandler。

??????????? 代碼：

代碼 public??class?ErrorWCFHandler
????{
???????public?static?void?Invoke<TContract>(TContract?proxy,?Action<TContract>?action,?string?MethodElapsedTimeText,?string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????try
????????????{
????????????????action(proxy);
????????????????(proxy?as?ICommunicationObject).Close();
????????????}
????????????catch?(CommunicationException?ex)
????????????{
????????????????(proxy?as?ICommunicationObject).Abort();
????????????????//Handle?Exception?????????????
????????????????//throw;
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????catch?(TimeoutException?ex)
????????????{
????????????????(proxy?as?ICommunicationObject).Abort();
????????????????//Handle?Exception?????????
????????????????//throw;
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception????????
????????????????//(proxy?as?ICommunicationObject).Close();??????
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText?+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????}
???????public?static?TReturn?Invoke<TContract,?TReturn>(TContract?proxy,?Func<TContract,?TReturn>?func,?string?MethodElapsedTimeText,?string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????TReturn?returnValue?=?default(TReturn);
????????????try
????????????{
????????????????returnValue?=?func(proxy);
????????????}
????????????catch?(CommunicationException?ex)
????????????{
????????????????(proxy?as?ICommunicationObject).Abort();
????????????????//Handle?Exception?????
????????????????//throw;
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????catch?(TimeoutException?ex)
????????????{
????????????????(proxy?as?ICommunicationObject).Abort();
????????????????//Handle?Exception???????
????????????????//throw;
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception??
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());
????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText?+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????????return?returnValue;
????????}
????}

????????? 客戶端調(diào)用：
??????????

代碼 string?ComputationTimeText="取積分廣場首頁酒店數(shù)據(jù)耗時:";
???????????string?ErrorMethodText="取積分廣場首頁酒店數(shù)據(jù)異常:";
???????????list?=?ErrorWCFHandler?.Invoke<ISearchHotelForSquare,?List<HotelGenericInfo>>(cli,?proxy?=>?proxy.GetHotelGenericListForSquare(requestInfo).ToList

(),ComputationTimeText?,ErrorMethodText?);??

?? ?? 第三：記錄方法調(diào)用時間，這中間也增加了異常處理：ErrorAndComputationTimeHandler

??????????? 代碼：

代碼 ?public?class?ErrorAndComputationTimeHandler
????{
????????public?static?void?Invoke<TContract>(TContract?proxy,?Action<TContract>?action,?string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????try
????????????{
????????????????action(proxy);

????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????}
????????public?static?void?Invoke<TContract,?TContract2>(TContract?proxy,?TContract2?proxy2,?Action<TContract,?TContract2>?action,?string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????try
????????????{
????????????????action(proxy,?proxy2);

????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????}
????????public?static?void?Invoke<TContract,?TContract2,?TContract3>(TContract?proxy,?TContract2?proxy2,?TContract3?proxy3,?Action<TContract,?TContract2,?TContract3>?action,?string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????try
????????????{
????????????????action(proxy,?proxy2,?proxy3);

????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????}
????????public?static?void?Invoke<TContract,?TContract2,?TContract3,?TContract4>(TContract?proxy,?TContract2?proxy2,?TContract3?proxy3,?TContract4?proxy4,?Action<TContract,?TContract2,?TContract3,?TContract4>?action,??string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????try
????????????{
????????????????action(proxy,?proxy2,?proxy3,?proxy4);

????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????}
????????public?static?TReturn?Invoke<TContract,?TReturn>(TContract?proxy,?Func<TContract,?TReturn>?func,??string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????TReturn?returnValue?=?default(TReturn);
????????????try
????????????{
????????????????returnValue?=?func(proxy);
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????????return?returnValue;
????????}
????????public?static?TReturn?Invoke<TContract,?TContract2,?TReturn>(TContract?proxy,?TContract2?proxy2,?Func<TContract,?TContract2,?TReturn>?func,??string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????TReturn?returnValue?=?default(TReturn);
????????????try
????????????{
????????????????returnValue?=?func(proxy,?proxy2);
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????????return?returnValue;
????????}
????????public?static?TReturn?Invoke<TContract,?TContract2,?TContract3,?TReturn>(TContract?proxy,?TContract2?proxy2,?TContract3?proxy3,?Func<TContract,?TContract2,?TContract3,?TReturn>?func,??string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????TReturn?returnValue?=?default(TReturn);
????????????try
????????????{
????????????????returnValue?=?func(proxy,?proxy2,?proxy3);
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();

????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????????return?returnValue;
????????}
????????public?static?TReturn?Invoke<TContract,?TContract2,?TContract3,?TContract4,?TReturn>(TContract?proxy,?TContract2?proxy2,?TContract3?proxy3,?TContract4?proxy4,?Func<TContract,?TContract2,?TContract3,?TContract4,?TReturn>?func,??string?MethodElapsedTimeText,string?MethodErrorText)
????????{
????????????Stopwatch?sw?=?new?Stopwatch();
????????????sw.Start();
????????????TReturn?returnValue?=?default(TReturn);
????????????try
????????????{
????????????????returnValue?=?func(proxy,?proxy2,?proxy3,?proxy4);
????????????}
????????????catch?(Exception?ex)
????????????{
????????????????//Handle?Exception???
????????????????WebLog.SquareLog.CommonLogger.Error(MethodErrorText?+?ex.ToString());

????????????}
????????????sw.Stop();
????????????WebLog.SquareLog.CommonLogger.Error(MethodElapsedTimeText??+?sw.ElapsedMilliseconds.ToString()?+?"毫秒");
????????????return?returnValue;
????????}
????}

??????????? 客戶端調(diào)用：?????

代碼 string?ComputationTimeText?=?"取酒店是否在積分廣場首頁推薦數(shù)據(jù)耗時:";
????????????string?ErrorMethodText?=?"取酒店是否在積分廣場首頁推薦數(shù)據(jù)異常:";
????????????string?conn?=?WebConfig.DaoConfig.MisMasterDBReadConnectionString;
????????????HotelRecommendInfo?=?ErrorAndComputationTimeHandler.Invoke<HotelRequestInfo,?string,?List<HotelGenericInfo>>(requestInfo,?conn,?SearchRecommendHotelData,?ComputationTimeText,?ErrorMethodText);

????

?????? AOP的優(yōu)勢：

　　 1:上述應用范例在沒有使用AOP情況下，也能解決，但是，AOP可以讓我們從一個更高的抽象概念來理解軟件系統(tǒng)。可以這么說：因為使用AOP結(jié)構(gòu)，對于一個大型復雜系統(tǒng)來說可以簡化不少代碼。

　　 2:并不是所有的人都需要關心AOP，使得其它開發(fā)人員有更多精力去關注自己的業(yè)務邏輯。

作者：姜敏
出處：http://www.cnblogs.com/aspnet2008/?

轉(zhuǎn)載于:https://www.cnblogs.com/ASPNET2008/archive/2010/04/18/1714528.html

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