Spring -Spring的 DI - 依赖注入的使用学习

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原小明呢 2023-05-07 15:50:48 ©著作权

文章标签 bean dao spring xml 赋值 文章分类 JavaScript 前端开发

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一 . spring的DI

依赖注入，一句话总结：给属性赋值；

一个类中的属性都可以采用springDI的方式进行赋值，但是并不是所有的属性都适合赋值；

示例：

（1）当前两个对象 Person和Student

--Person

package cn.labelnet.di.set;

public class Person {

}

--Student

package cn.labelnet.di.set;

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

public class Student {
	private Integer id;
	private String sName;
	private String sPass;
	private List stus;
	private Map maps;
	private Set sets;
	
	
	public Integer getId() {
		return id;
	}
	public void setId(Integer id) {
		this.id = id;
	}
	public String getSName() {
		return sName;
	}
	public void setSName(String name) {
		sName = name;
	}
	public String getSPass() {
		return sPass;
	}
	public void setSPass(String pass) {
		sPass = pass;
	}
	public List getStus() {
		return stus;
	}
	public void setStus(List stus) {
		this.stus = stus;
	}
	public Map<String, String> getMaps() {
		return maps;
	}
	public void setMaps(Map<String, String> maps) {
		this.maps = maps;
	}
	public Set getSets() {
		return sets;
	}
	public void setSets(Set sets) {
		this.sets = sets;
	}

}

（2）bean配置和赋值

<?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">

	<bean id="student" class="cn.labelnet.di.set.Student">

		<property name="id" value="1"></property>

		<property name="maps">

			<map>
				<entry key="m1">
					<value>yuan</value>
				</entry>
				<entry key="m2">
				    <value>zhuo</value>
				</entry>
				<entry key="m3">
				    <value>ming</value>
				</entry>
			</map>

		</property>
		
		<property name="sets">
		    
		    <set>
		       <value>h1</value>
		       <value>h2</value>
		       <ref bean="persion"/>
		       <value>h4</value>
		    </set>
		
		</property>
		
		<property name="SName">
			<value>LABELNET</value>
		</property>
		
		<property name="SPass"> 
		    <value>MMMMMMMM</value>
		</property>
		
		<property name="stus">
		     <list>
		       <ref bean="persion"/>
		       <ref bean="persion"/>
		     </list>
		</property>

	</bean>


	<bean id="persion" class="cn.labelnet.di.set.Person"></bean>
</beans>

（3）总结

1）引用类型使用ref

2）属性使用 property

3）list集合 list

4）set集合 set

5）map集合使用 map , entry

6）普通类型使用 value

1)如果Spring的配置文件中的bean中没有<constructor-arg>元素，则调用默认的构造函数；

2)如果Spring的配置文件中的bean中有<constructor-arg>元素，则该元素确定唯一的构造函数

index 代表参数的位置，从0开始

type 指的是参数的类型

value 给基本类型赋值

ref 给引用类型赋值

示例：

（1）实现类 Student

public class Person {
	
	private String name;
	private Integer age;
	private Student student;
	
	public Person(String name,Integer age,Student student) {
		this.name=name;
		this.age=age;
		this.student=student;
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Integer getAge() {
		return age;
	}

	public void setAge(Integer age) {
		this.age = age;
	}

	public Student getStudent() {
		return student;
	}

	public void setStudent(Student student) {
		this.student = student;
	}
}

（2）Student

public class Student {

	public void hi(){
		System.out.println("依赖注入 ：DI 构造函数赋值");
	}
	
}

（3）bean配置

<?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">
     
     <bean id="person_con" class="cn.labelnet.di.constructor.Person">
          <constructor-arg index="0" type="java.lang.String" value="yuan"></constructor-arg>
          <constructor-arg index="1" type="java.lang.Integer" value="18"></constructor-arg>
          <constructor-arg index="2" type="cn.labelnet.di.constructor.Student" ref="student_con"></constructor-arg>
     </bean>
     
     
     <bean id="student_con" class="cn.labelnet.di.constructor.Student"></bean>
     
</beans>

（4）测试

public class SpringInit {
	
	public final static ApplicationContext context;
	
    static{
    	context=new ClassPathXmlApplicationContext("ApplicationContext.xml");
    }

}

public class TestDIConstructor extends SpringInit{
	
	@Test
	public void testDICons(){
		
	   Person person=(Person) context.getBean("person_con");
	   System.out.println(person.getName()+" | "+person.getAge());
	   Student s = person.getStudent();
	   s.hi();
		
	}
	

}

（5）结果

Spring -Spring的 DI - 依赖注入的使用学习_dao

二. SpringIOC和DI的意义

实现了完全的面相接口编程

示例：person : child man oldman

描述：person接口，有个sayhi方法，使得child，man，oldman均实现person接口和sayhi方法

（1）Person接口

public interface Person {
	void sayHi();
}

（2）ChildPerson实现

public class ChildPerson implements Person {
	
	private String name;
	private Integer age;
     public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Integer getAge() {
		return age;
	}
	public void setAge(Integer age) {
		this.age = age;
	}
	public void sayHi(){
    	 System.out.println("小孩子："+this.name+this.age);
     }	
}

（3）ManPerson实现

package cn.labelnet.implement;

public class ManPerson implements Person{
	
	private String name;
	private Integer age;
	
	  public void sayHi(){
		  System.out.println("Man ："+this.name+this.age);
	     }
	  public String getName() {
			return name;
		}



		public void setName(String name) {
			this.name = name;
		}



		public Integer getAge() {
			return age;
		}



		public void setAge(Integer age) {
			this.age = age;
		}

}

（4）OldManPerson实现

package cn.labelnet.implement;

public class OldmanPerson implements Person {

	private String name;
	private Integer age;

	public void sayHi() {
		System.out.println("OldMan：" + this.name + this.age);
	}

	public String getName() {
		return name;
	}

	public void setName(String name) {
		this.name = name;
	}

	public Integer getAge() {
		return age;
	}

	public void setAge(Integer age) {
		this.age = age;
	}

}

（5）PersonManager实现

package cn.labelnet.implement;

public class PersonManager {
	
	private Person person;

	public Person getPerson() {
		return person;
	}

	public void setPerson(Person person) {
		this.person = person;
	}
	
	
	public void say(){
		person.sayHi();
	}

}

（6）bean配置实现

<?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">

	<bean id="child_person_impl" class="cn.labelnet.implement.ChildPerson">
		<property name="name" value="Child"></property>
		<property name="age" value="18"></property>
	</bean>

	<bean id="man_person_impl" class="cn.labelnet.implement.ManPerson">
		<property name="name" value="Man"></property>
		<property name="age" value="19"></property>

	</bean>

	<bean id="oldman_person_impl" class="cn.labelnet.implement.OldmanPerson">
		<property name="name" value="OldMan"></property>
		<property name="age" value="19"></property>
	</bean>
	
	<bean id="person_manager"  class="cn.labelnet.implement.PersonManager">
	
	   <property name="person" ref="child_person_impl"></property>
	
	 </bean>

</beans>

（7）测试

传统的测试方法：

Person per=new ChildPerson();
		PersonManager manager=new PersonManager();
		manager.setPerson(per);
		manager.say();

bean.xml测试

public class TestImplement extends SpringInit{
	
	@Test
	public void testImlp(){
		
		
		PersonManager manager=(PersonManager) context.getBean("person_manager");
		manager.say();
	}

}