spring 常用的注入方式有哪些？

spring 常用的注入方式有哪些？

1、xml中配置

bean 的申明、注册

节点注册 bean
节点的 factory-bean 参数指工厂 bean，factory-method 参数指定工厂方法

bean 的注入

节点使用 set 方式注入
节点使用构造方法注入

实测代码

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、 + ，set方法注入

class Bowl

package constxiong.interview.inject;public class Bowl {public void putRice() {System.out.println("盛饭...");}}

class Person

package constxiong.interview.inject;public class Person {private Bowl bowl;public void eat() {bowl.putRice();System.out.println("开始吃饭...");}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.xsdhttp://www.springframework.org/schema/contexthttp://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>

测试类

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、修改为配置文件和class Person， + 节点使用构造方法注入

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("开始吃饭...");}}

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.xsdhttp://www.springframework.org/schema/contexthttp://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、节点 factory-method 参数指定静态工厂方法

工厂类，静态工厂方法

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.xsdhttp://www.springframework.org/schema/contexthttp://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、非静态工厂方法，需要指定工厂 bean 和工厂方法

工厂类，非静态工厂方法

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.xsdhttp://www.springframework.org/schema/contexthttp://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、注册

@Component //注册所有bean
@Controller //注册控制层的bean
@Service //注册服务层的bean
@Repository //注册dao层的bean

bean 的注入

@Autowired 作用于构造方法、字段、方法，常用于成员变量字段之上。
@Autowired + @Qualifier 注入，指定 bean 的名称
@Resource JDK 自带注解注入，可以指定 bean 的名称和类型等

测试代码

E、spring 配置文件，设置注解扫描目录

<?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.xsdhttp://www.springframework.org/schema/contexthttp://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 //注册所有bean
//@Controller //注册控制层的bean
//@Service //注册服务层的bean
//@Repository //注册dao层的bean
public class Bowl {public void putRice() {System.out.println("盛饭...");}}

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 //注册所有bean
//@Controller //注册控制层的bean
//@Service //注册服务层的bean
//@Repository //注册dao层的bean
public class Person {@Autowired
//  @Qualifier("bowl")
//  @Resource(name="bowl")private Bowl bowl;public void eat() {bowl.putRice();System.out.println("开始吃饭...");}}

测试类同上

A、B、C、D、E 测试结果都ok

盛饭...
开始吃饭...

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