Spring's Dependency Injection di (IOC)

1. Manual Injection

(1) Set injection

 Public class userservice {        private  Userdao Userdao;          Public void Setuserdao (Userdao dao) {        this. userdao = dao;    }} 

    class= "Com.spring1.dao.UserDao" ></bean>         class= " Com.spring1.service.UserService ">        <property name=" Userdao "ref=" UserDao1 "></property>    </bean>    

The USERDAO1 is injected through the Setuserdao method of the UserService object.

 Public classUser {intID;    String name;    String password;  Public intgetId () {returnID; }     Public voidSetId (intID) { This. ID =ID; }     PublicString GetName () {returnname; }     Public voidsetName (String name) { This. Name =name; }     PublicString GetPassword () {returnpassword; }     Public voidSetPassword (String password) { This. Password =password; }}

 Public class Userdao {        publicvoid  setshowuser (user user) {        System.out.println ( User.getid ()+ ":" +user.getname () + ":" +User.getpassword ());}    }

    class= "Com.spring1.entity.User" >        <property name= "id" value= "1" ></property>        < Property name= "Name" value= "Zhangsan" ></property>        <property name= "password" value= "123456" >< /property>    </bean>        class= "Com.spring1.dao.UserDao" >        <property name= " Showuser "ref=" user "></property>    </bean>

Initializes the user in the bean configuration, userDao1 the user by its own Setshowuser method

(2) Construction method injection

    class= "Com.spring1.dao.UserDao" >    </bean>    class= " Com.spring1.service.UserService ">        <constructor-arg name=" UserDao1 "ref=" UserDao1 "></ Constructor-arg>    </bean>

    @Test    publicvoid  Test () {                new Classpathxmlapplicationcontext ("Applicationcontext.xml");         = (UserService) ac.getbean ("Testservice");        Service.showuser ();        }

 Public class userservice {        private  Userdao Userdao;          Public UserService (Userdao userDao1) {        this. Userdao = Userdao;    }           Public void Showuser () {        System.out.print ("OK-------------");    }    }

The name of the constructor parameter, corresponding to the name of the constructor parameter of the class.

2. Automatic injection

    class= "Com.spring1.dao.UserDao" ></bean>        class= "Com.spring1.service.UserService" Autowire= "ByName" >    </bean>

Id=userdao2, the Setuserdao2==userdao2 below is the same.

 Public class userservice {        private  Userdao Userdao;          Public void SetUserDao2 (Userdao userDao1) {        this. Userdao = userDao1;    }           Public void Showuser () {       userdao.showuser ();     }    }

When ByName is automatically injected, it is necessary to top a bean with a parameter name in the Name= class

Spring's Dependency Injection di (IOC)