Understanding of Spring Dependency Injection

First of all:

1. Dependency injection is a way to define an interface in a class that needs to use it, regardless of how this interface is implemented, just execute this method

2. Dependency injection allows the class to implement generic

Code:

1. Define a beverage interface

1  PackageCn.lonecloud.model;2 /**3 * Create a food interface4 * @Title: Idrink.java5 * @Package Cn.lonecloud6 * @Description:7  * @authorLonecloud8 * @date October 4, 2016 morning 9:39:319  */Ten  Public InterfaceiDRINK { One      Public  voiddrink (); A}

2. Write its implementation class

1  PackageCn.lonecloud.model;2 3 4 /**5 * Milk6 * @Title: Milk.java7 * @Package Cn.lonecloud8 * @Description:9  * @authorLonecloudTen * @date October 4, 2016 morning 9:42:17 One  */ A  Public classMilkImplementsiDRINK { -  - @Override the      Public voiddrink () { -         //TODO auto-generated Method Stub -System.out.println ("Drink milk"); -     } +      -      +}

1  PackageCn.lonecloud.model;2 3 4  Public classWaterImplementsiDRINK {5 6 @Override7      Public voiddrink () {8         //TODO auto-generated Method Stub9System.out.println ("Drink");Ten     } One  A}

1  PackageCn.lonecloud.model;2 3  Public classCoffeeImplementsiDRINK {4 5 @Override6      Public voiddrink () {7         //TODO auto-generated Method Stub8System.out.println ("Drink is coffee");9     }Ten  One}

These three implementation classes are the implementation of this beverage interface

3. Write Customer Class

1  PackageCn.lonecloud;2 3 ImportCn.lonecloud.model.IDrink;4 5 /**6 * Customer Category7 * @Title: Customer.java8 * @Package Cn.lonecloud9 * @Description:Ten  * @authorLoneloud One * @date October 4, 2016 morning 9:47:32 A  */ -  Public classCustomer { -     /** the * Use this to inject alcohol into customers ' drinks -      * @paramMydrink -      */ -      PublicCustomer (iDRINK mydrink) { +         //TODO auto-generated Constructor stub -          This. mydrink=Mydrink; +     } A      PublicCustomer () { at         //TODO auto-generated Constructor stub -     } -      Public voidSenddrink (idrink drink) { -          This. mydrink=drink; -     } -     /** in * Customers choose a drink to drink -      */ to     PrivateiDRINK Mydrink; +     /** - * Customers drink drinks the * @Description: *      */ $      Public voiddrinking () {Panax Notoginseng Mydrink.drink (); -     } the}

The customer drinks The drink, defines the interface and can then use the definition method or constructs the method to carry on the realization to this beverage.

5. Test method

1  PackageCn.lonecloud;2 3 Importorg.junit.Test;4 5 ImportCn.lonecloud.model.Coffee;6 ImportCn.lonecloud.model.IDrink;7 8  Public classCustomertest {9     Ten     /** One * Using this kind of words can make the customer class become universal A * @Description: -      */ - @Test the      Public voidtestbyconstract () { -iDRINK drink=NewCoffee (); -         //This allows for the injection of beverages -Customer customer=NewCustomer (drink); + customer.drinking (); -     } +     /** A * Injection using the method body at * @Description: -      */ - @Test -      Public voidTestbymethod () { -iDRINK drink=NewCoffee (); -Customer customer=NewCustomer (); in         //This allows for the injection of beverages - Customer.senddrink (drink); to customer.drinking (); +     } -}

Understanding of Spring Dependency Injection