spring 常用的注入方式有哪些？
1、xml中配置bean 的申明、注册
<bean> 节点注册 bean
<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
<property> 节点使用 set 方式注入
<constructor-arg> 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、<bean> + <property>，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.
xmlns:xsi="http://www.
xmlns:context="http://www.
xsi:schemaLocation="
http://www.
http://www.
http://www.
http://www.
<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，<bean> + <constructor-arg> 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.
xmlns:xsi="http://www.
xmlns:context="http://www.
xsi:schemaLocation="
http://www.
http://www.
http://www.
http://www.
<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> 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.
xmlns:xsi="http://www.
xmlns:context="http://www.
xsi:schemaLocation="
http://www.
http://www.
http://www.
http://www.
<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.
xmlns:xsi="http://www.
xmlns:context="http://www.
xsi:schemaLocation="
http://www.
http://www.
http://www.
http://www.
<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 //外汇返佣http://www.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.
xmlns:xsi="http://www.
xmlns:context="http://www.
xsi:schemaLocation="
http://www.
http://www.
http://www.
http://www.
<context:component-scan base-package="constxiong.interview" />
</beans>
class Bowl
package constxiong.interview.inject;
import org.springframework.
//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.
@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...
