Inversion of Control1. Hollywood's Principle: Don't call me, I'll call you2. Instead of lookup the resource we want. We leave it to the framework
Traditional 'Pull Approach'
Context ctx = new initialContext (); accountEJB AccountEJB = (AccountEJB) CTX.lookup ("java: comp / ENV / EJB / AccountEJB");
Drawback: 1. Client Codes Tied to a Specific Implementation2. Codes Are Difficult To Test (Must Be Tested within the Container)
IOC Approach:
Private Account AccountManager; Public Void SetAccountManager (Account Account) {this.accountManager = Accent;}
AddVantage: 1. Client Code Does Not Need To DEAL WITH COMPONENT Discovery2. Client Code Isn't Tied to Any Specific Implementations3. Codes Can Unit Testing? Individually with Mock Object
3 Types:
TYPE 1: Interface Injection?
Dependency Satisfied by Interfaces IT IMPLEMENTED
TYPE 2: Setter Injection
Dependency Satisfied by JavaBean Properties and ITS SETER EXPOSED BY A Component
Type 3: Constructor Injection
Dependedcy Satisfied by The Component's Construction
