Spring Bean instantiation three methods: constructors, static factory, factory instance

Spring Bean in the equivalent of java in the class, can be configured and managed by bean xml file.

A, Bean instantiation:

Examples of the constructor, static factory instantiated, instantiate an instance factory.

table of Contents:

Examples of builder:

xml configuration file:

 

id unique, calss designated Bean implementation class, must be fully qualified class name, you can right-click on "public class Bean1" in Bean1 in Bean1.java file, select Copy Qualifiel Name get. Note the use of "." Separated.

Test function:

First test function defined in xml configuration file path, you can select the right directory view Copy Qualifiel Name to get attention from the com start here, because it is the path separated by /.

Then loading a configuration file to instantiate Bean, id specified by the obtained function getBean instance object, note type conversion.

Complete code:

package com.liu.instance.contructor;

public class Bean1 {

}

Bean1.java

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="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-4.3.xsd">
    <bean id="bean1" class="com.liu.instance.contructor.Bean1"></bean>
</beans>

beans1.xml

Package com.liu.instance.contructor; 

Import org.springframework.context.ApplicationContext;
 Import org.springframework.context.support.ClassPathXmlApplicationContext; 

public  class InstanceTest { 

    public  static  void main (String [] args) {
         // definition configuration file path 
        XMLPath = String "COM / Liu / instance / contructor / beans1.xml" ;
         // to be instantiated ApplicationContext Bean load configuration file. 
        ApplicationContext = ApplicationContext new new ClassPathXmlApplicationContext (XMLPath);
         // the above mentioned id configuration file to determine which bean, java objects found in files created by class.
        Bean1 bean1 = (Bean1) applicationContext.getBean("bean1");
        System.out.println(bean1);
        
    
    }
}

InstanceTest.java

Run shot:

 

Examples of static factory:

xml configuration file:

unique id, class for class factory, factory-method is the method name, method to identify which plant.

Static factory class:

 Static method returns a Bean2 object.

Package com.liu.instance.static_factory;
 / * 
 * LSQ 
 * 2019-9-10 
 * static factory instantiates the Spring instantiated Bean2 
 * / 
public  class Bean2 { 

}

Bean2.java

Package com.liu.instance.static_factory;
 / * 
 * LSQ 
 * 2019-9-10 
 * static factory to instantiate the Spring 
 * / 

public  class MyBean2Factory { 

    // create objects Bean2 
    public  static Bean2 createBean2 () {
         return  new new Bean2 (); 
    } 
}

MyBean2Factory.java

Package com.liu.instance.static_factory; 

Import org.springframework.context.ApplicationContext;
 Import org.springframework.context.support.ClassPathXmlApplicationContext; 

/ * 
 * LSQ 
 * 2019-9-10 
 * the Spring a static factory test class instance object 
 * / 
public  class InstanceTest { 

    public  static  void main (String [] as AGRS) {
         // definition configuration file path 
        String XMLPath = "COM / Liu / instance / static_factory / beans2.xml" ;
         // instantiate an object of 
        the ApplicationContext the ApplicationContext = new new the ClassPathXmlApplicationContext (XMLPath );
         //Calling function
         // the getBean id attribute value acquisition function passing objects 
        System.out.println (to applicationContext.getBean ( "bean2" )); 
    } 
}

InstanceTest.java

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="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-4.3.xsd">


    <bean id="bean2" class="com.liu.instance.static_factory.MyBean2Factory"
        factory-method="createBean2">
    </bean>
</beans>

beans2.xml

 Run shot: 

 

Examples of factory instance:

xml configuration file:

 The first two bean static factory class static factory, class. The second is bean3, factory-method property configuration example plant, factory-method to determine which method to use in the plant.

Factory class:

 Returns a Bean3 object.

Complete code:

Package com.liu.instance.factory;
 / * 
 * LSQ 
 * 2019-9-10 
 * Examples of the Spring factory object 
 * / 
public  class Bean3 { 

}

Bean3.java

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="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-4.3.xsd">


    <bean id="bean2" class="com.liu.instance.static_factory.MyBean2Factory"
        factory-method="createBean2">
    </bean>
</beans>

bean3.xml

Package com.liu.instance.factory;
 / * 
 * LSQ 
 * 2019-9-10 
 * Examples of the Spring factory object 
 * / 
public  class MyBean3Factory { 

    public MyBean3Factory () { 
        System.out.println ( "Bean3 plant instantiation .. . " ); 
    } 
    public Bean3 createBean3 () {
         return  new new Bean3 (); 
    } 
}

MyBean3Factory.java

Package com.liu.instance.factory; 

Import org.springframework.context.ApplicationContext;
 Import org.springframework.context.support.ClassPathXmlApplicationContext; 

/ * 
 * LSQ 
 * 2019-9-10 
 * factory to instantiate the Spring test class 
 * / 
public  class {InstanceTest3 

    public  static  void main (String [] args) {
         // the specified configuration file path 
        String XMLPath = "COM / Liu / instance / Factory / bean3.xml" ;
         // when ApplicationContext loading configuration file to instantiate Bean 
        ApplicationContext = applicationContext new new the ClassPathXmlApplicationContext (XMLPath);
        
        System.out.println(applicationContext.getBean("bean3"));
    }
}

InstanceTest3.java

Run shot:

 

The difference between the three methods: