spring dependency injection

! <- spring in the dependency injection 
        Dependency Injection: 
            Dependency Injection 
        role of the IOC: 
            to reduce the coupling (dependencies) between programs 
        dependencies management: 
            after all to spring to maintain the 
        need to use other types of objects in the current class, provides us with the spring, we just need to explain in the configuration file 
        maintenance dependencies: 
            it is called dependency injection 
        dependency injection: 
            can inject data: there are three 
                basic types String and 
                other bean types (in the configuration file or the configuration notes off the bean) 
                complex type / collection type 
            injection ways: three 
                first: using the provided constructor 
                second: providing method using the set 
                third: annotations provided
     ->

---

    <! - Constructor injection: 
        Tags used: constructor - Age 
        location tag appear: internal bean tag 
        label attribute 
            type: type of data used to specify the data to be injected, the data type is a constructor certain parameters or type 
            index: injecting data used to specify the index position of the specified parameter assigned to the constructor, the location index starts from 0 
            name: specifies the name of the parameter assigned to the constructor (conventional)
             = assigning three or more ================== ==================== for which parameter to the constructor = 
            value: for a basic type String and data of type 
            ref: other bean types for the specified data. It refers to appear in the spring of IOC core container had bean objects 

        advantage: 
            while acquiring bean object, inject data is a must, otherwise the object can not be created successfully 
        drawbacks: 
            change the instantiation way bean object, so that we when you create an object, if not these data must also be provided. 
    -> 
    <the bean ID = "AccountService" class="cn.flypig666.service.impl.AccountServiceImpl">
        <constructor-arg name="name" value="飞猪"></constructor-arg>
        <constructor-arg name="age" value="20"></constructor-arg>
        <constructor-arg name="birthday" ref="now"></constructor-arg>
    </bean>

    <!--配置一个日期对象-->
    <bean id="now" class="java.util.Date"></bean>

---

public  class AccountServiceImpl the implements IAccountService { 

    // If the data is constantly changing, does not apply to the injection manner 
    Private String name;
     Private Integer Age;
     Private a Date Birthday; 

    public AccountServiceImpl (name String, Integer Age, a Date Birthday) {
         the this .name = name;
         the this .age = Age;
         the this .birthday = Birthday; 
    } 

    public  void saveAccount () { 

        System.out.println ( "saveAccount method of performing service ....." + name + "," + age + ", "+ Birthday); 
    } 
}