spring常用的注入方式有哪些？

1、xml中配置

• bean 的申明、注冊

<bean> 節點注冊 bean
<bean> 節點的 factory-bean 參數指工廠 bean，factory-method 參數指定工廠方法

 

• bean 的注入

<property> 節點使用 set 方式注入
<constructor-arg> 節點使用 構造方法注入

 

實測代碼

maven pom 文件 

<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-beans</artifactId>
	<version>4.2.4.RELEASE</version>
</dependency>

<dependency>
	<groupId>org.springframework</groupId>
	<artifactId>spring-context</artifactId>
	<version>4.2.4.RELEASE</version>
</dependency>

 

a) <bean> + <property>，set方法注入

class Bowl

package constxiong.interview.inject;

public class Bowl {

	public void putRice() {
		System.out.println("盛飯...");
	}

}

class Person

package constxiong.interview.inject;

public class Person {

	private Bowl bowl;
	
	public void eat() {
		bowl.putRice();
		System.out.println("開始吃飯...");
	}

	public void setBowl(Bowl bowl) {
		this.bowl = bowl;
	}
	
}

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"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
	    http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="bowl" class="constxiong.interview.inject.Bowl" />
	
	<bean id="person" class="constxiong.interview.inject.Person">
		<property name="bowl" ref="bowl"></property>
	</bean>
	
</beans>

測試類

package constxiong.interview.inject;

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

public class InjectTest {

	public static void main(String[] args) {
		ApplicationContext context = new ClassPathXmlApplicationContext("spring_inject.xml");
		Person person = (Person)context.getBean("person");
		person.eat();
	}
}

 

 b) 修改為 配置文件和class Person，<bean> + <constructor-arg> 節點使用 構造方法注入

class Person

package constxiong.interview.inject;
 
public class Person {
 
	private Bowl bowl;
	
	public Person(Bowl bowl) {
		this.bowl = bowl;
	}
	
	public void eat() {
		bowl.putRice();
		System.out.println("開始吃飯...");
	}
	
}

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"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
	    http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="bowl" class="constxiong.interview.inject.Bowl" />
	
	<bean id="person" class="constxiong.interview.inject.Person">
		<constructor-arg name="bowl" ref="bowl"></constructor-arg>
	</bean>
	
</beans>

 

c) <bean> 節點 factory-method 參數指定靜態工廠方法

工廠類，靜態工廠方法

package constxiong.interview.inject;
 
public class BowlFactory {
 
	public static final Bowl getBowl() {
		return new Bowl();
	}
	
}

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"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
	    http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<bean id="bowl" class="constxiong.interview.inject.BowlFactory" factory-method="getBowl"/>
	
	<bean id="person" class="constxiong.interview.inject.Person">
		<constructor-arg name="bowl" ref="bowl"></constructor-arg>
	</bean>
	
</beans>

 

d) 非靜態工廠方法，需要指定工廠 bean 和工廠方法

工廠類，非靜態工廠方法

package constxiong.interview.inject;
 
public class BowlFactory {
 
	public Bowl getBowl() {
		return new Bowl();
	}
	
}

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"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
	    http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
    
    <bean id="bowlFactory" class="constxiong.interview.inject.BowlFactory"></bean>   
	<bean id="bowl" factory-bean="bowlFactory" factory-method="getBowl"/>
	
	<bean id="person" class="constxiong.interview.inject.Person">
		<constructor-arg name="bowl" ref="bowl"></constructor-arg>
	</bean>
	
</beans>

 

2、注解

• bean 的申明、注冊

@Component //注冊所有bean
@Controller //注冊控制層的bean
@Service //注冊服務層的bean
@Repository //注冊dao層的bean

 

• bean 的注入

@Autowired 作用於 構造方法、字段、方法，常用於成員變量字段之上。
@Autowired + @Qualifier 注入，指定 bean 的名稱
@Resource JDK 自帶注解注入，可以指定 bean 的名稱和類型等

 

測試代碼

e) spring 配置文件，設置注解掃描目錄

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
	xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
	xmlns:context="http://www.springframework.org/schema/context"
	xsi:schemaLocation="
		http://www.springframework.org/schema/beans 
		http://www.springframework.org/schema/beans/spring-beans.xsd
	    http://www.springframework.org/schema/context
        http://www.springframework.org/schema/context/spring-context.xsd">
        
	<context:component-scan base-package="constxiong.interview" />
	
</beans>

 

class Bowl

package constxiong.interview.inject;
 
import org.springframework.stereotype.Component;
//import org.springframework.stereotype.Controller;
//import org.springframework.stereotype.Repository;
//import org.springframework.stereotype.Service;
 
@Component //注冊所有bean
//@Controller //注冊控制層的bean
//@Service //注冊服務層的bean
//@Repository //注冊dao層的bean
public class Bowl {
 
	public void putRice() {
		System.out.println("盛飯...");
	}
 
}

 

class Person

package constxiong.interview.inject;
 
//import javax.annotation.Resource;
//
import org.springframework.beans.factory.annotation.Autowired;
//import org.springframework.beans.factory.annotation.Qualifier;
import org.springframework.stereotype.Component;
 
@Component //注冊所有bean
//@Controller //注冊控制層的bean
//@Service //注冊服務層的bean
//@Repository //注冊dao層的bean
public class Person {
 
	@Autowired
//	@Qualifier("bowl")
//	@Resource(name="bowl")
	private Bowl bowl;
 
	public void eat() {
		bowl.putRice();
		System.out.println("開始吃飯...");
	}
	
}

 

測試類同上

 

a、b、c、d、e 測試結果都ok

盛飯...
開始吃飯...

原文鏈接
 

---

• Java 自學經歷
• Java 面試題 H5
• Java 面試題小程序