How SPRINGIOC_ objects are created

Several ways that spring creates objects

1. The default construct
2. Static Factory
3. Instance Factory

One: default constructor method to create an object

1.applicationcontext.xml

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5. XSD ">               <BeanID= "HelloWorld"class= "Com.spring.createobject.method.HelloWord"></Bean>    </Beans>

2. Test class

 Package Com.spring.createobject.method;  Public class Helloword {        public  Helloword () {        System.out.println ("Create object");    }          Public void Hello () {        System.out.println ("Hello word!" );    }}

3, test

   /**       * In the spring container, the default constructor for a class is called by default to create an object  */  public  void   Testcreateobject_default () { //  Kai Move Spring container  applicationcontext context= new  Classpathxmlap                Plicationcontext ("Applicationcontext.xml" );         //  Extract the beans from the spring container by ID                 Helloword Helloword = (Helloword) context.getbean ("HelloWorld" );                    Helloword.hello (); }

Output:

Create Object
Hello word!

Two: Static factory-created objects

1.applicationcontext.xml

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5. XSD ">    <!--Factory-method refers to a static factory method -    <BeanID= "HelloWord2"class= "Com.spring.createobject.method.factory.HelloWordFactory"Factory-method= "GetInstance"></Bean>        </Beans>

2. Test class

 Package Com.spring.createobject.method;  Public class Helloword {        public  Helloword () {        System.out.println ("Create object");    }          Public void Hello () {        System.out.println ("Hello word!" );    }}

 Package com.spring.createobject.method.factory; Import Com.spring.createobject.method.HelloWord; // Static Factory Method  Public class hellowordfactory {        publicstatic  Helloword getinstance () {                 return New Helloword ();    }}

3. Testing

/*** * Create objects with static Factory mode * <bean id= "HelloWord2" class= "Com.spring.createobject.method.factory.HelloWord        Factory "factory-method=" getinstance "></bean> Spring container internally called getinstance method in Hellowordfactory to create object     The process of the specific new object is done by the programmer. */@Test Public voidtestcreateobject_staticfactory () {//start the spring containerApplicationContext context=NewClasspathxmlapplicationcontext ("Applicationcontext.xml"); //extract the beans from the spring container according to the IDHelloword Helloword = (Helloword) context.getbean ("HelloWord2");    Helloword.hello (); }

Output:

Create Object
Hello word!

Three: Instance factory creation Object

1.applicationcontext.xml

<?XML version= "1.0" encoding= "UTF-8"?><Beansxmlns= "Http://www.springframework.org/schema/beans"Xmlns:xsi= "Http://www.w3.org/2001/XMLSchema-instance"xsi:schemalocation= "Http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans-2.5. XSD ">                      <BeanID= "Hellowordfactory"class= "Com.spring.createobject.method.factory.HelloWordFactory2"></Bean>        <!--Factory-bean is a factory bean that invokes the object that Hellowordfactory points to, and then calls GetInstance to create the object Factory-method is a factory method -        <BeanID= "Helloword3"Factory-bean= "Hellowordfactory"Factory-method= "GetInstance"></Bean>                </Beans>

2. Test class

 Package Com.spring.createobject.method;  Public class Helloword {        public  Helloword () {        System.out.println ("Create object");    }          Public void Hello () {        System.out.println ("Hello word!" );    }}

 Package com.spring.createobject.method.factory; Import Com.spring.createobject.method.HelloWord;  Public class HelloWordFactory2 {        public  helloword getinstance () {                return  New  Helloword ();    }}

3. Testing

/**      * Instance Factory method      */     @Test    publicvoid  Testcreateobject_instancecfactory () {                // start Spring container        applicationcontext context=                New classpathxmlapplicationcontext ("Applicationcontext.xml");                 // extract the beans from the spring container according to the ID        Helloword Helloword = (Helloword) context.getbean ("Helloword3");        Helloword.hello ();    }

Output:

Create Object
Hello word!

How SPRINGIOC_ objects are created