spring容器IOC创建对象<三>

时间：2021-09-06 07:01:58
问题？Spring的DI讲解、DI有几种注入方式、

一、spring的DI：依赖注入给属性赋值
DI定义：一个对象类的属性可以使用springDI(依赖注入)来进行赋值,但是并不是所有的类属性都适合springDI来赋值.,
一共有两种方式进行属性赋值：set方法和带参构造方法

案例1：setting方法为对象类属性赋值
Person类 
package cn.itcast.sh.spring.di;
import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class Person {
	private Long pid;
	private String pname;
	private Student student;
	private List lists;
	private Map map;
	private Properties properties;
	private Set sets;

	public Long getPid() {
		return pid;
	}
	public void setPid(Long pid) {
		this.pid = pid;
	}
	public String getPname() {
		return pname;
	}
	public void setPname(String pname) {
		this.pname = pname;
	}
	public Student getStudent() {
		return student;
	}
	public void setStudent(Student student) {
		this.student = student;
	}
	public List getLists() {
		return lists;
	}
	public void setLists(List lists) {
		this.lists = lists;
	}
	public Map getMap() {
		return map;
	}
	public void setMap(Map map) {
		this.map = map;
	}
	public Properties getProperties() {
		return properties;
	}
	public void setProperties(Properties properties) {
		this.properties = properties;
	}
	public Set getSets() {
		return sets;
	}
	public void setSets(Set sets) {
		this.sets = sets;
	}
}

Student类、

package cn.itcast.sh.spring.di;
public class Student {
}

配置文件：

<?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-2.5.xsd">

			<!-- 先把person和student放入到spring容器中 -->
           <!-- SpringDI：依赖注入,本质就是向对象类的属性赋值 -->

           <!-- 用setting方式来为属性赋值 -->
           <bean id="person" class="cn.itcast.sh.spring.di.Person">
           	 <!--
	 			 property是用来描述一个类的属性
	 			   基本类型的封装类、String等需要值的类型用value赋值
				引用类型用ref赋值(一般是对象的注入)
			  -->
           		<property name="pid" value="2"></property>
           		<property name="pname" value="lijun"></property>
           		<property name="lists">
           			<list>
           				<value>list1</value>
           				<value>list2</value>
           				<ref bean="student"/>
           			</list>
           		</property>
           		<property name="map">
           			<map>
           				<entry key="m1">
           					<value>map1</value>
           				</entry>
           				<entry key="map2">
           					<ref bean="student"/>
           				</entry>
           			</map>
           		</property>
           		<!-- properties:只有String类型 -->
           		<property name="properties">
           			<props>
           				<prop key="p1">p1的值</prop>
           				<prop key="p2">p2的值</prop>
           			</props>
           		</property>
           		<property name="sets">
           			<set>
           				<value>set第一个值</value>
           				<value>set第二值</value>
           				<ref bean="student"/>
           			</set>
           		</property>
           		<property name="student">
           			<ref bean="student"/>
           		</property>
           </bean>

           <bean id="student" class="cn.itcast.sh.spring.di.Student"></bean>
</beans>

测试类：

package cn.itcast.sh.spring.ioc.test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import cn.itcast.sh.spring.di.Person;
import cn.itcast.sh.spring.di.Student;

public class IDTest {
	@Test
	public void A(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Person person = (Person)applicationContext.getBean("person");
		System.out.println(person.getPid());
		System.err.println(person.getStudent());
		System.out.println("--------------");
		System.out.println(person.getLists());
		System.out.println("--------------");
		System.out.println(person.getMap());
		System.out.println("--------------");
		System.out.println(person.getProperties());
		System.out.println("--------------");
		System.out.println(person.getSets());

	}
}

结果图片处：

spring容器IOC创建对象<三>

案例2：带参构造器为对象类属性赋值

Person类

package cn.itcast.sh.spring.di.constructor;

import java.util.List;
import java.util.Map;
import java.util.Properties;
import java.util.Set;

public class Person {
	private String pname;
	private Student student;

	private void person() {}//如果写的有带参构造方法，一定要写默认的构造方法

	public Person(String pname,Student student){
		this.pname = pname;
		this.student = student;
	}

	public String getPname() {
		return pname;
	}

	public Student getStudent() {
		return student;
	}

}

配置文件：

<?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-2.5.xsd">

			<!-- 先把person和student放入到spring容器中 -->
           <!-- SpringDI：依赖注入,本质就是向对象类的属性赋值 -->

           <!-- 用构造函数的方式为属性赋值(
           		如果没有constructor-arg：默认情况下是调用的无参构造函数，
           		如果有constructor-arg：则调用带参数的构造函数) 

           		注：一个bean只能确认一个构造函数，因此在对象类中不能出现两个构造函数
           	-->

           <bean id="personConstructor" class="cn.itcast.sh.spring.di.constructor.Person">
           <!--
           	index:表示构造函数参数的位置
           	type:表示参数的类型
           	value:表示给基本类型赋值
           	ref：表示给引用类型赋值
            -->
           	<constructor-arg index="0" type="java.lang.String" value="aaa"></constructor-arg>
           	<constructor-arg index="1" type="cn.itcast.sh.spring.di.constructor.Student" ref="studentConstructor"></constructor-arg>
           </bean>

           <bean id="studentConstructor" class="cn.itcast.sh.spring.di.constructor.Student"></bean>
</beans>

测试类：

package cn.itcast.sh.spring.ioc.test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import cn.itcast.sh.spring.di.constructor.Person;

public class DIConstructorTest {
	@Test
	public void A(){
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("applicationContext.xml");
		Person person = (Person)applicationContext.getBean("personConstructor");
		System.out.println(person.getPname());
		person.getStudent().B();
	}
}

结果图片处：
spring容器IOC创建对象<三>

案例写到这里;我们就可能要提一个问题了，那我们用这个方式来干甚呢？

用spring这种赋值方式，我们可以实现属性的赋值，还可以实现对象的注入，在我们进行对象的实现的时候，就不需要我们来做了，全部交给spring容器来做。

二、springIOC和DI的意义

意义：不完全面接口编程----->变成完全的接口编程(也就是将对象的产生给了sprin*生，我们不需要关心是谁来实现的接口)

案例：spring+MVC模式

action层

package cn.itcast.sh.spring.mvc;
public class PersonAction {
	private PersonService personService;

	public PersonService getPersonService() {
		return personService;
	}

	public void setPersonService(PersonService personService) {
		this.personService = personService;
	}

	public void savePerson1(){
		this.personService.savePerson();
	}
}

service接口层及实现

package cn.itcast.sh.spring.mvc;

public interface PersonService {
	public void savePerson();
}

package cn.itcast.sh.spring.mvc;

public class PersonServiceImp implements PersonService {
	private PersonDao personDao;

	public PersonDao getPersonDao() {
		return personDao;
	}
	public void setPersonDao(PersonDao personDao) {
		this.personDao = personDao;
	}

	public void savePerson() {
		this.personDao.savePerson();
	}

}

Dao接口层及实现

package cn.itcast.sh.spring.mvc;

public interface PersonDao {
	public void savePerson();
}
package cn.itcast.sh.spring.mvc;

public class PersonDaoImp implements PersonDao {

	public void savePerson() {
		System.out.println("sava Person Dao!!");
	}

}

spring配置文件

<?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-2.5.xsd">
           <!-- Spring模拟MVC -->
           <bean id="personDao" class="cn.itcast.sh.spring.mvc.PersonDaoImp"></bean>
           <!-- 这里采用的是setting方法进行注入的 -->
           <bean id="personService" class="cn.itcast.sh.spring.mvc.PersonServiceImp">
           		<property name="personDao">
           			<ref bean="personDao"/>
           		</property>
           </bean>

           <bean id="personAction" class="cn.itcast.sh.spring.mvc.PersonAction">
           	  <property name="personService">
           	  		<ref bean="personService"/>
           	  </property>
           </bean>
</beans>

测试类：

package cn.itcast.sh.spring.ioc.test;

import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;

import cn.itcast.sh.spring.mvc.PersonAction;
import cn.itcast.sh.spring.util.SpringUtil;

public class MVCTest  {
	@Test
	public void A(){
		ApplicationContext applicationContext = new  ClassPathXmlApplicationContext("applicationContext.xml");
		PersonAction personAction = (PersonAction)applicationContext.getBean("personAction");
		personAction.savePerson1();
	}
}

结果图片处：

spring容器IOC创建对象<三>

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