6/20/2013
5:31:00 PM 0

JavaScript 變數宣告(使用 var 與不使用 var 的區別)

JavaScript 變數使用 var 來宣告, 如果不使用 var, 則屬於 global object a = 1; //global function init() { b = 2; //global var c = 3; //local } function test1() { init(); console.log(a); console.log(b); console.log(c); } test1(); output -------------------------------------------- 1 2 exception : ReferenceError: c is not defined 變數宣告後在作用範圍內都有效 function test2() { console.log(a); var a = 1; console.log(a); } test2(); output -------------------------------------------- undefined 1 注意...
6/07/2013
3:03:00 PM 0

Service Locator Pattern

將取得服務的方法進行封裝, 可降低程式碼間的耦合度 import javax.naming.Context; import javax.naming.InitialContext; import javax.naming.NamingException; import javax.sql.DataSource; import java.util.Collections; import java.util.HashMap; import java.util.Map; public final class ServiceLocator { private static ServiceLocator sl = new ServiceLocator(); private Context c; private Map m; private ServiceLocator() { try { c = new InitialContext(); m = Collections.synchronizedMap(new HashMap()); ...