What are the three ways of spring ioc injection?

The three ways of spring ioc injection are: 1. Setter method injection. After the container instantiates the bean by calling the parameterless constructor or parameterless static factory method, it calls the setter method of the bean. 2. Constructor method injection. 3. P namespace injection.

#The operating environment of this tutorial: windows7 system, java8 version, Dell G3 computer.

Spring IOC (three methods of dependency injection):

1. Setter method injection

Setter method injection is when the container instantiates a bean by calling a parameterless constructor or a parameterless static factory method, and then calls the setter method of the bean, which implements setter-based dependency injection.

package com.jpeony.spring.setter;
import com.jpeony.spring.common.HelloServiceImpl;public class HelloWord {
private HelloService helloService;
 
    // setter方式注入Bean
    public void setHelloService(HelloService helloService) {
        this.helloService = helloService;
    }
 
    @Override
    public void selfIntroduction() {
        // 向大家打招呼
        helloService.sayHello("大家好!");
    }
 
}

<?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.xsd">
    <!--
       Bean声明:
         该bean类似于javaConfig中的@Bean注解;
         用于创建bean的类通过class属性来指定，并且需要使用全限定的类名。
         通过id指定bean的ID。如果不显示指定，默认使用class的全限定名进行命名。
         eg:
         com.jpeony.spring.common.HelloServiceImpl#0，其#0是一个计数器的形式，
         用来区分相同类型的其他bean。
         使用自动化命名很方便，但是没有多少实际用处，还是建议自己给bean显示设定ID。
     -->
    <bean id="helloService" class="com.jpeony.spring.common.HelloServiceImpl"/>
 
    <!-- setter注入bean -->
    <bean id="HelloWord" class="com.jpeony.spring.setter.HelloWord">
        <property name="helloService" ref="helloService"/>
    </bean>
 
</beans>

2. Constructor injection

Constructor dependency injection is implemented by triggering the constructor of a class through the container. The class has a series of Parameters, each parameter represents a dependency on other classes.

package com.jpeony.spring.setter;
import com.jpeony.spring.common.HelloServiceImpl;

public class HelloWord {
    private HelloService helloService;
 
    // 构造方法注入
    public HelloWord (HelloService helloService) {
        this.helloService = helloService;
    }
 
}

<?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.xsd">
    <!--
       Bean声明:
         该bean类似于javaConfig中的@Bean注解;
         用于创建bean的类通过class属性来指定，并且需要使用全限定的类名。
         通过id指定bean的ID。如果不显示指定，默认使用class的全限定名进行命名。
         eg:
         com.jpeony.spring.common.HelloServiceImpl#0，其#0是一个计数器的形式，
         用来区分相同类型的其他bean。
         使用自动化命名很方便，但是没有多少实际用处，还是建议自己给bean显示设定ID。
     -->
    <bean id="helloService" class="com.jpeony.spring.common.HelloServiceImpl"/>
 
    <!-- 构造方法注入bean -->
    <bean id="HelloWord" class="com.jpeony.spring.setter.HelloWord">
        <constructor-arg><ref bean="helloService"/></constructor-arg>
    </bean>
 
</beans>

3. P namespace injection

package com.jpeony.spring.setter;
import com.jpeony.spring.common.HelloServiceImpl;

public class HelloWord {
    //名字
    private String name;
    //年龄
    private String age;
    //方法类
    private HelloService helloService;
 
    public void setName (String name) {
        this.name = name;
    }
    
    public void setAge (String age) {
        this.age = age;
    }
    
    public void setHelloService(HelloService helloService) {
        this.helloService = helloService;
    }
 
    @Override
    public void selfIntroduction() {
        // 向大家打招呼
        helloService.sayHello("我叫"+ name + "，今年" + age + "岁，大家好!");
    }
 
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       <!-- 引入p命名标签 -->
       xmlns:p="http://www.springframework.org/schema/p"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="helloService" class="com.jpeony.spring.common.HelloServiceImpl"/>
 
    <!-- p标签注入bean -->
    <bean id="HelloWord" class="com.jpeony.spring.setter.HelloWord" 
     p:name="明明" p:age="24" p:helloService-ref="helloService"></bean>
 
</beans>

P tag injection collection bean

package com.jpeony.spring.setter;
import com.jpeony.spring.common.HelloServiceImpl;
import java.util.List;

public class HelloWord {
    //名字
    private String name;
    //年龄
    private String age;
    //方法类
    private List<HelloService> helloServices;
 
    public void setName (String name) {
        this.name = name;
    }
    
    public void setAge (String age) {
        this.age = age;
    }
    
    public void setHelloServices(List<HelloService> helloServices) {
        this.helloServices = helloServices;
    }
 
    @Override
    public void selfIntroduction() {
        // 向大家打招呼
        helloServices[0].sayHello("我叫"+ name + "，今年" + age + "岁，大家好!");
    }
 
}

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
       xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
       <!-- 引入p命名标签 -->
       xmlns:p="http://www.springframework.org/schema/p"
       <!-- 引入util命名标签 -->
       xmlns:util="http://www.springframework.org/schema/util"
       xsi:schemaLocation="http://www.springframework.org/schema/beans http://www.springframework.org/schema/beans/spring-beans.xsd">
    
    <bean id="helloService" class="com.jpeony.spring.common.HelloServiceImpl"/>

    <bean id="helloService2" class="com.jpeony.spring.common.HelloServiceImpl">
    ...........
    </bean>
 
    <util:list id="helloServices">
        <ref bean="helloService"/>
        <ref bean="helloService2"/>
    </util:list>

    <!-- p标签注入bean -->
    <bean id="HelloWord" class="com.jpeony.spring.setter.HelloWord" 
     p:name="明明" p:age="24" p:helloServices-ref="helloServices"></bean>
 
</beans>

For more knowledge about computer programming, please visit: Introduction to Programming! !

The above is the detailed content of What are the three ways of spring ioc injection?. For more information, please follow other related articles on the PHP Chinese website!