springIOC和DI的意义

springIOC和DI的意义：

实现了完全的面向接口编程document案例MVC案例 Document案例-使用构造方法的依赖注入
接口

public interface Document {
void read();
void write();
}

实现类1

public class WordDocument implements Document {
public void read() {
System.out.println("word read");
}
public void write() {
System.out.println("word writer");
}
}

实现类2

public class PDFDocument implements Document {
public void read() {
System.out.println("pdf read");
}
public void write() {
System.out.println("pdf write");
}
}

工具类

public class DocumentManager {
public Document document;
public DocumentManager(Document document){
this.document = document;
}
public void read(){
document.read();
}
public void write(){
document.write();
}
}

测试

public class Test1 {
@Test
public void test1(){
ApplicationContext context = new  ClassPathXmlApplicationContext("applicationContext.xml");
DocumentManager manager = (DocumentManager) context.getBean("DocumentManager");
manager.read();
manager.write();
}
}

spring配置文件applicationContext.xml

<bean id="DocumentManager" class="spring_ioc_di_document.DocumentManager">
<constructor-arg index="0" ref="pdfDocument"></constructor-arg></bean>
<bean id="wordDocument" class="spring_ioc_di_document.WordDocument"></bean>
<bean id="pdfDocument" class="spring_ioc_di_document.PDFDocument"></bean>

mvc案例-使用set方式依赖注入dao接口

public interface PersonDao {
public void read();
}

dao实现

public class PersonDaoImpl implements PersonDao  {
public void read() {
System.out.println("personDao read");
}
}

service接口

public interface PersonService {
public void read();
}

service实现

public class PersonServiceImpl implements PersonService{
PersonDao persondao;
public PersonDao getPersondao() {
return persondao;
}
public void setPersondao(PersonDao persondao) {
this.persondao = persondao;
}
@Override
public void read() {
persondao.read();
}
}

测试

public class Test2 {
@Test
public void test2(){
ApplicationContext context = new ClassPathXmlApplicationContext("applicationContext.xml");
PersonAction action = (PersonAction) context.getBean("PersonAction");
action.read();
}
}

spring配置文件applicationContext.xml

<bean id="personDao" class="spring_mvc.PersonDaoImpl"></bean>
<bean id="personService" class="spring_mvc.PersonServiceImpl" >
<property name="persondao" >
<ref bean="personDao"/>
</property>
<bean id="PersonAction" class="spring_mvc.PersonAction">
<property name="service">
<ref bean="personService"/>
</property>
</bean>