< go > A simple description of dependency injection:

Scenario: There is now a disk-output business that the client needs to output through 2 business objects. One is via floppy (floppy disk) and the other is via USB interface.

1. define an interface

For example:

Package spring.basic.BusinessFactory;

Public interface Idevicewriter {

public void Savetodevice ();

}

2. defines a class that implements an interface (overriding interface methods)

For example: (two classes that implement interfaces are defined here)

Class Floppywriter:

Package spring.basic.BusinessFactory;

public class Floppywriter implements Idevicewriter {

public void Savetodevice () {

System.out.println ("Save to Floppy disk ...");

}

}

Class Usbdiskwriter:

Package spring.basic.BusinessFactory;

public class Usbdiskwriter implements Idevicewriter {

public void Savetodevice () {

System.out.println ("Save to Mobile HDD ...");

}

}

3. Defining the Business class (specifying the functionality of the class)

Package spring.basic.BusinessFactory;

public class Businessbean {

Private Idevicewriter writer;

public void Setdevicewriter (Idevicewriter writer) {

This.writer = writer;

}

Public Idevicewriter Getdevicewriter () {

return writer;

}

public void Save () {

if (writer = = null) {

throw new RuntimeException ("Devicewriter needed ...");

}

Writer.savetodevice ();

}

}

4. Defining a configuration file (writes the class that implements the interface and the business class to the configuration file)

For example:

<?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-2.0.xsd ">

<bean id= "Floppy" class= "Spring.basic.BusinessFactory.FloppyWriter"/>

<bean id= "USB" class= "Spring.basic.BusinessFactory.UsbDiskWriter"/>

<bean id= "Businessbean"

class= "Spring.basic.BusinessFactory.BusinessBean" >

<property name= "Devicewriter" >

<ref bean= "Floppy"/>

</property>

</bean>

</beans>

5. Defining client Code

Package spring.basic.BusinessFactory;

Import Org.springframework.context.ApplicationContext;

Import Org.springframework.context.support.ClassPathXmlApplicationContext;

public class Springdemo {

public static void Main (string[] args) {

ApplicationContext context = new Classpathxmlapplicationcontext (

"Businessfactoryconfig.xml");

Businessbean business = (Businessbean) context.getbean ("Businessbean");

Business.save ();

}

}

< go > A simple description of dependency injection: