spring 依赖注入的5中方式

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spring中如何给对象的属性复制?

1)通过构造方法

2)通过set方法给属性注入值

3)p命名空间

4)自动转配(了解即可,不推荐使用)

5)注解

准备工作（模拟业务方法）Action-->service-->dao

1)UserDao:

p<span style="font-family:Courier New;">ublic class UserDao {
	public void save(){
		System.out.println("save方法");
	}
}</span>

p<span style="font-family:Courier New;">ublic class UserService {
	private UserDao userDao;
	public void setUserDao(UserDao userDao) {
		this.userDao = userDao;
	}
	public void save(){
		userDao.save();
	}
}</span>

<span style="font-family:Courier New;">public class UserAction {
	private UserService userService;
	public void setUserService(UserService userService) {
		this.userService = userService;
	}
	public String execute(){
		userService.save();
		return null;
	}
}</span>

public class App {
	ApplicationContext ac=new ClassPathXmlApplicationContext("cn/itcast/property/bean.xml");
	@Test
	public void test(){
		UserAction userAction=(UserAction) ac.getBean("userAction");
		System.out.println(userAction.execute());
	}
}

<?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:p="http://www.springframework.org/schema/p"
    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">
</beans>

1)必须保证有set方法

<bean id="userDao" class="cn.itcast.property.UserDao"></bean>
	<bean id="userService" class="cn.itcast.property.UserService">
		<property name="userdao" ref="userDao"></property>
	</bean>
	<bean id="userAction" class="cn.itcast.property.UserAction">
		<property name="userService"  ref="userService"></property>
	</bean>

bean id="userAction" class="cn.itcast.property.UserAction">
		<property name="userService">
			<bean id="userService" class="cn.itcast.property.UserService">
				<property name="userDao">
					<bean id="userDao" class="cn.itcast.property.UserDao"></bean>
				</property>
			</bean>
		</property>
	</bean>

<bean id="userDao" class="cn.itcast.property.UserDao"></bean>
	<bean id="userService" class="cn.itcast.property.UserService" p:userdao-ref="userDao"></bean>
	<bean id="userAction" class="cn.itcast.property.UserAction" p:userService-ref="userService"></bean>

<!-- 根据“名称”自动装配： userAction注入的属性，会去ioc容器中自动查找与属性同名的对象 -->

<bean id="userDao" class="cn.itcast.property.UserDao" ></bean>
	 <bean id="userService" class="cn.itcast.property.UserService" autowire="byName"></bean>
	 <bean id="userAction" class="cn.itcast.property.UserAction" autowire="byName"></bean>

使用注解步骤：

1）先引入context名称空间

xmlns:context="http://www.springframework.org/schema/context"

2）开启注解扫描

 <context:component-scanbase-package="cn.itcast.e_anno2"></context:component-scan>

3）使用注解

通过注解的方式，把对象加入ioc容器。

创建对象以及处理对象依赖关系，相关的注解：

@Component   指定把一个对象加入IOC容器

@Repository   作用同@Component； 在持久层使用

@Service      作用同@Component； 在业务逻辑层使用

@Controller    作用同@Component； 在控制层使用

@Resource     属性注入

<!-- 开启扫描机制 -->
	 <context:component-scan base-package="cn.itcast.property"></context:component-scan>

@Repository
public class UserDao {
	public void save(){
		System.out.println("save方法");
	}
}

@Service
public class UserService {
	@Resource
	private UserDao userDao;
	public void save(){
		userDao.save();
	}
}

@Controller
public class UserAction {
	@Resource
	private UserService userService;
	public String execute(){
		userService.save();
		return null;
	}
}

spring 依赖注入的5中方式

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原文地址：http://blog.csdn.net/u014010769/article/details/47134997