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.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>
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.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、 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.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.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.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...
