C#事件和委托

public void ChineseGreeting(string name){ Console.WriteLine("ᮽϞད, " + name); }
䖭ᯊ‫*ˈ׭‬UHHW3HRSOH г䳔㽕ᬍϔᬍњˈϡ✊བԩ߸ᮁࠄᑩ⫼ાϾ⠜ᴀⱘ *UHHWLQJ 䯂‫׭‬ᮍ ⊩ড়䗖ਸ਼˛೼䖯㸠䖭ϾПࠡˈ៥Ӏ᳔ད‫ݡ‬ᅮНϔϾᵮВ԰Ў߸ᮁⱘձ᥂˖
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㘾ᯢⱘԴᑨ䆹Ꮖ㒣ᛇࠄњˈ⦄೼ᰃྨᠬ䆹ߎഎⱘᯊ‫׭‬њˈԚ䆆䗄ྨᠬПࠡˈ៥Ӏ‫ⳟⳟݡ‬ 0DNH*UHHWLQJ খ᭄᠔㛑ҷ㸼ⱘ&KLQHVH*UHHWLQJ ੠ (QJOLVK*UHHWLQJ ᮍ⊩ⱘㅒৡ˖
public void EnglishGreeting(string name) public void ChineseGreeting(string name)
public void GreetPeople(string name, GreetingDelegate MakeGreeting){ MakeGreeting(name); }
བԴ᠔㾕ˈྨᠬ *UHHWLQJ'HOHJDWH ߎ⦄ⱘԡ㕂ϢVWULQJ ⳌৠˈVWULQJ ᰃϔϾ㉏ൟˈ䙷М *UHHWLQJ'HOHJDWH ᑨ䆹гᰃϔϾ㉏ൟˈ ៪㗙ি㉏ &ODVV DŽ Ԛᰃྨᠬⱘໄᯢᮍᓣ੠㉏ैᅠܼϡৠˈ 䖭ᰃᗢМϔಲџ˛ᅲ䰙Ϟˈྨᠬ೼㓪䆥ⱘᯊ‫⹂׭‬ᅲӮ㓪䆥៤㉏DŽ಴Ў 'HOHJDWH ᰃϔϾ㉏ˈ᠔ҹ ೼ӏԩৃҹໄᯢ㉏ⱘഄᮍ䛑ৃҹໄᯢྨᠬDŽ᳈໮ⱘ‫ݙ‬ᆍᇚ೼ϟ䴶䆆䗄ˈ⦄೼ˈ䇋ⳟⳟ䖭Ͼ㣗՟ⱘ ᅠᭈҷⷕ˖
ᇚᮍ⊩԰Ўᮍ⊩ⱘখ᭄
៥Ӏ‫ܜ‬ϡㅵ䖭Ͼᷛ乬བԩⱘ㒩ষˈ гϡㅵྨᠬおコᰃϾҔМϰ㽓ˈ ᴹⳟϟ䴶䖭ϸϾ᳔ㅔऩⱘ ᮍ⊩ˈᅗӀϡ䖛ᰃ೼ሣᐩϞ䕧ߎϔহ䯂‫ⱘ׭‬䆱䇁˖
public void GreetPeople(string name) { // ‫خ‬ᶤѯ乱໪ⱘџᚙˈ↨བ߱ྟ࣪П㉏ˈℸ໘⬹ EnglishGreeting(name); } public void EnglishGreeting(string name) { Console.WriteLine("Morning, " + name); }
using System; using System.Collections.Generic; using System.Text;
namespace Delegate { //ᅮНྨᠬˈᅗᅮНњৃҹҷ㸼ⱘᮍ⊩ⱘ㉏ൟ public delegate void GreetingDelegate(string name); class Program {
Hale Waihona Puke Baidu
GreetPeople("Jimmy Zhang", delegate1); GreetPeople("ᓴᄤ䰇", delegate2); Console.ReadKey(); }
བԴ᠔᭭ˈ䖭ḋᰃ≵᳝䯂乬ⱘˈ⿟ᑣϔབ乘᭭ⱘ䙷ḋ䕧ߎDŽ䖭䞠ˈ៥ᛇ䇈ⱘᰃྨᠬϡৠѢ VWULQJ ⱘϔϾ⡍ᗻ˖ৃҹᇚ໮Ͼᮍ⊩䌟㒭ৠϔϾྨᠬˈ៪㗙িᇚ໮Ͼᮍ⊩㒥ᅮࠄৠϔϾྨᠬˈ ᔧ䇗⫼䖭Ͼྨᠬⱘᯊ‫ˈ׭‬ᇚձ⃵䇗⫼݊᠔㒥ᅮⱘᮍ⊩DŽ೼䖭Ͼ՟ᄤЁˈ䇁⊩བϟ˖
᱖Ϩϡㅵ䖭ϸϾᮍ⊩᳝≵᳝ҔМᅲ䰙ᛣНDŽ*UHHW3HRSOH ⫼Ѣ৥ᶤҎ䯂དˈᔧ៥ӀӴ䗦ҷ㸼 ᶤҎྦྷৡⱘ QDPH খ᭄ˈ↨བ䇈Ā-LPP\ā ˈ䖯এⱘᯊ‫ˈ׭‬೼䖭Ͼᮍ⊩Ёˈᇚ䇗⫼ (QJOLVK*UHHWLQJ ᮍ⊩ˈ‫⃵ݡ‬Ӵ䗦 QDPH খ᭄ˈ(QJOLVK*UHHWLQJ ߭⫼Ѣ৥ሣᐩ䕧ߎĀ0RUQLQJ-LPP\ā DŽ ⦄೼‫؛‬䆒䖭Ͼ⿟ᑣ䳔㽕䖯㸠ܼ⧗࣪ˈઢਔˈϡདњˈ៥ᰃЁ೑Ҏˈ៥ϡᯢⱑĀ0RUQLQJāᰃ ҔМᛣᗱˈᗢМࡲਸ਼˛ད৻ˈ៥Ӏ‫ࡴݡ‬ϾЁ᭛⠜ⱘ䯂‫׭‬ᮍ⊩˖
public void GreetPeople(string name, Language lang)
៥ӀҙⳟVWULQJ QDPHˈ೼䖭䞠ˈVWULQJᰃখ᭄㉏ൟˈQDPHᰃখ᭄ব䞣ˈᔧ៥Ӏ䌟㒭 QDPH ᄫヺІĀMLPP\āᯊˈᅗህҷ㸼ĀMLPP\ā䖭Ͼؐ˗ᔧ៥Ӏ䌟㒭ᅗĀᓴᄤ䰇āᯊˈᅗজҷ㸼ⴔĀᓴ ᄤ䰇ā䖭ϾؐDŽ✊ৢˈ៥Ӏৃҹ೼ᮍ⊩ԧ‫ݙ‬ᇍ䖭Ͼ QDPH 䖯㸠݊Ҫ᪡԰DŽઢˈ䖭ㅔⳈᰃᑳ䆱Мˈ ߮ᄺ⿟ᑣህⶹ䘧њDŽ བᵰԴ‫ݡ‬Ҩ㒚ᛇᛇˈ‫؛‬བ *UHHW3HRSOH ᮍ⊩ৃҹ᥹ফϔϾখ᭄ব䞣ˈ䖭Ͼব䞣ৃҹҷ㸼঺ ϔϾᮍ⊩ˈᔧ៥Ӏ㒭䖭Ͼব䞣䌟ؐ(QJOLVK*UHHWLQJ ⱘᯊ‫ˈ׭‬ᅗҷ㸼ⴔ(QJOVLK*UHHWLQJ 䖭 Ͼᮍ⊩˗ᔧ៥Ӏ㒭ᅗ䌟ؐ &KLQHVH*UHHWLQJⱘᯊ‫ˈ׭‬ᅗজҷ㸼ⴔ &KLQHVH*UHHWLQJ ᮍ⊩DŽ៥Ӏ ᇚ䖭Ͼখ ᭄ ব䞣ੑৡ Ў 0DNH*UHHWLQJ ˈ䙷Мϡ ᰃৃҹབ ৠ 㒭 QDPH 䌟ؐᯊϔḋ ˈ ೼䇗⫼ *UHHW3HRSOH ᮍ⊩ⱘᯊ‫ˈ׭‬㒭䖭Ͼ 0DNH*UHHWLQJখ᭄г䌟ϞؐМ &KLQHVH*UHHWLQJ ៪㗙 (QJOVLK*UHHWLQJ ㄝ ˛✊ৢˈ ៥Ӏ೼ᮍ⊩ԧ‫ˈݙ‬ гৃҹ‫ڣ‬Փ⫼߿ⱘখ᭄ϔḋՓ⫼ 0DNH*UHHWLQJDŽ Ԛ ᰃ ˈ ⬅ Ѣ 0DNH*UHHWLQJ ҷ 㸼 ⴔ ϔ Ͼ ᮍ ⊩ ˈ ᅗ ⱘ Փ ⫼ ᮍ ᓣ ᑨ 䆹 ੠ ᅗ 㹿 䌟 ⱘ ᮍ ⊩ ↨ བ &KLQHVH*UHHWLQJ ᰃϔḋⱘˈ↨བ˖
public delegate void GreetingDelegate(string name);
ৃҹϢϞ䴶 (QJOLVK*UHHWLQJ ᮍ⊩ⱘㅒৡᇍ↨ϔϟˈ䰸њࡴܹњ GHOHJDWH ݇䬂ᄫҹ໪ˈ ݊ԭⱘᰃϡᰃᅠܼϔḋ˛ ⦄೼ˈ䅽៥Ӏ‫⃵ݡ‬ᬍࡼ *UHHW3HRSOH ᮍ⊩ˈབϟ᠔冫˖
public enum Language{ English, Chinese }
public void GreetPeople(string name, Language lang){ //‫خ‬ᶤѯ乱໪ⱘџᚙˈ↨བ߱ྟ࣪П㉏ˈℸ໘⬹ swith(lang){ case Language.English: Page 2 of 20
EnglishGreeting(name); break; case Language.Chinese: ChineseGreeting(name); break; } }
2.ˈሑㅵ䖭ḋ㾷‫އ‬њ䯂乬ˈԚ៥ϡ䇈໻ᆊгᕜᆍᯧᛇࠄˈ䖭Ͼ㾷‫އ‬ᮍḜⱘৃᠽሩᗻᕜᏂˈབ ᵰ᮹ৢ៥Ӏ䳔㽕‫䶽ࡴ⏏ݡ‬᭛⠜ǃ᮹᭛⠜ˈህϡᕫϡড໡ׂᬍᵮВ੠ *UHHW3HRSOH ᮍ⊩ˈҹ䗖ᑨ ᮄⱘ䳔∖DŽ ೼㗗㰥ᮄⱘ㾷‫އ‬ᮍḜПࠡˈ៥Ӏ‫*ⳟⳟܜ‬UHHW3HRSOH ⱘᮍ⊩ㅒৡ˖
private static void EnglishGreeting(string name) { Page 4 of 20
Console.WriteLine("Morning, " + name); }
private static void ChineseGreeting(string name) { Console.WriteLine("ᮽϞད, " + name); }
䕧ߎབϟ˖ Morning, Jimmy Zhang ᮽϞད, ᓴᄤ䰇
៥Ӏ⦄೼ᇍྨᠬ‫خ‬ϔϾᘏ㒧˖ ྨᠬᰃϔϾ㉏ˈᅗᅮНњᮍ⊩ⱘ㉏ൟˈՓᕫৃҹᇚᮍ⊩ᔧ԰঺ϔϾᮍ⊩ⱘখ᭄ᴹ䖯㸠Ӵ䗦ˈ 䖭辵ᇚᮍ⊩ࡼᗕഄ䌟㒭খ᭄ⱘ‫ৃˈ⊩خ‬ҹ䙓‫ܡ‬೼⿟ᑣЁ໻䞣Փ⫼ ,I(OVH 6ZLWFK 䇁হˈৠᯊՓ ᕫ⿟ᑣ‫݋‬᳝᳈དⱘৃᠽሩᗻDŽ
MakeGreeting(name);
དњˈ᳝њᗱ䏃њˈ៥Ӏ⦄೼ህᴹᬍᬍ *UHHW3HRSOH ᮍ⊩ˈ䙷Мᅗᑨ䆹ᰃ䖭Ͼḋᄤњ˖
public void GreetPeople(string name, *** MakeGreeting){ MakeGreeting(name); }
⊼ᛣࠄ ˈ䖭Ͼԡ㕂䗮ᐌᬒ㕂ⱘᑨ䆹ᰃখ᭄ⱘ㉏ൟˈԚࠄⳂࠡЎℶˈ៥Ӏҙҙᰃᛇࠄᑨ 䆹᳝Ͼৃҹҷ㸼ᮍ⊩ⱘখ᭄ˈ ᑊᣝ䖭Ͼᗱ䏃এᬍ‫* ݭ‬UHHW3HRSOH ᮍ⊩ˈ ⦄೼ህߎ⦄њϔϾ໻䯂乬˖ 䖭Ͼҷ㸼ⴔᮍ⊩ⱘ 0DNH*UHHWLQJ খ᭄ᑨ䆹ᰃҔМ㉏ൟⱘ˛ 127(˖䖭䞠Ꮖϡ‫ݡ‬䳔㽕ᵮВњˈ಴Ў೼㒭 0DNH*UHHWLQJ 䌟ؐⱘᯊ‫ࡼ׭‬ᗕഄ‫އ‬ᅮՓ⫼ાϾᮍ ⊩ˈ ᰃ &KLQHVH*UHHWLQJ 䖬ᰃ(QJOLVK*UHHWLQJˈ 㗠೼䖭ϾϸϾᮍ⊩‫ݙ‬䚼ˈ Ꮖ㒣ᇍՓ⫼ ĀPRUQLQJā 䖬ᰃĀᮽϞདā԰њऎߚDŽ
//⊼ᛣℸᮍ⊩ˈᅗ᥹ফϔϾ GreetingDelegate ㉏ൟⱘᮍ⊩԰Ўখ᭄ private static void GreetPeople(string name, GreetingDelegate MakeGreeting) { MakeGreeting(name); }
static void Main(string[] args) { GreetPeople("Jimmy Zhang", EnglishGreeting); GreetPeople("ᓴᄤ䰇", ChineseGreeting); Console.ReadKey(); } } }
བৠ QDPH ৃҹ᥹ফ 6WULQJ ㉏ൟⱘĀWUXHā੠Āā ˈԚϡ㛑᥹ফ ERRO ㉏ൟⱘ WUXH ੠ LQW 0DNH*UHHWLQJ ⱘখ᭄㉏ൟᅮНᑨ䆹㛑໳⹂ᅮ0DNH*UHHWLQJ ৃҹҷ㸼ⱘᮍ⊩ ㉏ൟⱘ ϔḋDŽ0 辵㉏ˈ‫ݡ‬䖯ϔℹ䆆ˈህᰃ 0DNH*UHHWLQJ ৃҹҷ㸼ⱘᮍ⊩ⱘখ᭄㉏ൟ੠䖨ಲ㉏ൟDŽ Ѣ ᰃ ˈ ྨ ᠬ ߎ ⦄ њ ˖ ᅗ ᅮ Н њ 0DNH*UHHWLQJ খ ᭄ ᠔ 㛑 ҷ 㸼 ⱘ ᮍ ⊩ ⱘ 辵 ㉏ ˈ г ህ ᰃ 0DNH*UHHWLQJ খ᭄ⱘ㉏ൟDŽ 127(˖བᵰϞ䴶䖭হ䆱↨䕗㒩ষˈ៥ᡞᅗ㗏䆥៤䖭ḋ˖VWULQJᅮНњ QDPH খ᭄᠔㛑ҷ㸼ⱘ ؐⱘ辵㉏ˈгህᰃ QDPH খ᭄ⱘ㉏ൟDŽ ᴀ՟ЁྨᠬⱘᅮН˖
}
㗠᮶✊ྨᠬ *UHHWLQJ'HOHJDWH੠㉏ൟVWULQJⱘഄԡϔḋˈ䛑ᰃᅮНњϔ辵খ᭄㉏ൟˈ 䙷Мˈ៥ᰃϡᰃгৃҹ䖭МՓ⫼ྨᠬ˛
static void Main(string[] args) { GreetingDelegate delegate1, delegate2; delegate1 = EnglishGreeting; delegate2 = ChineseGreeting;
C# Ёⱘྨᠬ੠џӊ
Delegates and Events in C#
჆ᆐཽ
www.tracefact.net
jimmy_dev@163.com
ᓩ㿔
ྨᠬ੠џӊ೼1HW)UDPHZRUN Ёⱘᑨ⫼䴲ᐌᑓ⊯ˈ✊㗠ˈ䕗དഄ⧚㾷ྨᠬ੠џӊᇍᕜ໮ ᥹㾺 &ᯊ䯈ϡ䭓ⱘҎᴹ䇈ᑊϡᆍᯧDŽᅗӀህ‫ڣ‬ᰃϔ䘧ᾯ‫ˈܓ‬䖛њ䖭ϾᾯⱘҎˈ㾝ᕫⳳᰃ໾ᆍᯧ њˈ㗠≵᳝䖛এⱘҎ↣⃵㾕ࠄྨᠬ੠џӊህ㾝ᕫᖗ䞠߿˄ELk˅ᕫᜠˈ⏋䑿ϡ㞾೼DŽᴀ᭛Ёˈ៥ ᇚ䗮䖛ϸϾ㣗՟⬅⌙ܹ⏅ഄ䆆䗄ҔМᰃྨᠬǃЎҔМ㽕Փ⫼ྨᠬǃџӊⱘ⬅ᴹǃ1HW )UDPHZRUN Ёⱘྨᠬ੠џӊǃྨᠬ੠џӊᇍ 2EVHUYHU 䆒䅵῵ᓣⱘᛣНˈᇍᅗӀⱘЁ䯈ҷⷕг‫خ‬њ䅼䆎DŽ
ᇚᮍ⊩㒥ᅮࠄྨᠬ
ⳟࠄ䖭䞠ˈᰃϡᰃ᳝䙷М⚍བṺ߱䝦ⱘᛳ㾝˛ѢᰃˈԴᰃϡᰃ೼ᛇ˖೼Ϟ䴶ⱘ՟ᄤЁˈ៥ϡ ϔᅮ㽕Ⳉ᥹೼ *UHHW3HRSOH ᮍ⊩Ё㒭QDPH খ᭄䌟ؐˈ៥ৃҹ‫ڣ‬䖭ḋՓ⫼ব䞣˖
static void Main(string[] args) { string name1, name2; name1 = "Jimmy Zhang"; name2 = "ᓴᄤ䰇"; GreetPeople(name1, EnglishGreeting); GreetPeople(name2, ChineseGreeting); Console.ReadKey(); Page 5 of 20