Bean配置形式：

Bean配置形式:

           ①. 基于 XML 文件的方式

      ②. 基于注解的方式

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~分割线~~~~~~~~~~~~~~~~~~~~~~~~~~~

 ①. 基于 XML 文件的方式

       applicationContext.xml

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

	<!-- 配置Bean -->
	<bean id="person" class="com.baidu.spring.beans.test.Person">
		<property name="name" value="LiLei"></property>
	</bean>

</beans>

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~分割线~~~~~~~~~~~~~~~~~~~~~~~~~~~

②. 基于注解的方式

(1). 在classPath 中扫描组件：

com.baidu.beans.annotation 基包 下的类

TestObject.java

package com.baidu.beans.annotation;

import org.springframework.stereotype.Component;

@Component
public class TestObject {

}

测试方法：TestSpringAnnotationBeans.java

package com.baidu.beans.annotation;

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

import com.baidu.beans.annotation.controller.UserController;
import com.baidu.beans.annotation.repository.UserRepository;
import com.baidu.beans.annotation.servlice.UserService;

public class TestSpringAnnotationBeans {
	
	public static void main(String[] args) {
		
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans_annotation.xmll.xml");
		
//		TestObject to = (TestObject) applicationContext.getBean("testObject");
//		System.out.println(to);
//		
//		UserController uc = (UserController) applicationContext.getBean("userController");
//		System.out.println(uc);
//		
//		UserService us = (UserService) applicationContext.getBean("userService");
//		System.out.println(us);
		
		UserRepository ur = (UserRepository) applicationContext.getBean("userRepository");
		System.out.println(ur);
		
	}
}

com.baidu.beans.annotation.controller下的类
UserController.java

package com.baidu.beans.annotation.controller;

import org.springframework.stereotype.Controller;

@Controller
public class UserController {
	
	public void execute(){
		System.out.println("UserController execute....");
	}
}

com.baidu.beans.annotation.servlice下的类

package com.baidu.beans.annotation.servlice;

import org.springframework.stereotype.Service;

@Service
public class UserService {
	
	public void add() {
		System.out.println("UserService add....");
	}
}

com.baidu.beans.annotation.repository 下的类

UserRepository.java

package com.baidu.beans.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository {

	void save();
}

UserRepositoryImpl.java

package com.baidu.beans.annotation.repository;

import org.springframework.stereotype.Repository;

/**
 * Spring 有默认的命名策略：使用非限定类名，只一个字母小写，
 * 		也可以咋注解中通过vale 属性值标识组件的名称 ,如：@Repository("userRepository")
 */
@Repository("userRepository")
public class UserRepositoryImpl implements UserRepository {

	@Override
	public void save() {
		System.out.println("UserRepositoryImpl Save....");
	}

}

基于注解的方式配置bean

<?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-4.0.xsd">

	<!--~~~~~~~~~~~~~~~~~~~~ 指定Spring IOC容器扫描的包 ~~~~~~~~~~~~~~~~~~~~-->
	<!--
		resource-pattern:指定扫描那个特定包下的资源，其他的子包将不被扫描
		如：resource-pattern="repository/*.class" 将只能扫描repository包下的资源，
												其他的兄弟包下的资源将不会被扫描
		 
	<context:component-scan base-package="com.baidu.beans.annotation"
		resource-pattern="repository/*.class"></context:component-scan>
	-->
	
	
	<!-- context:exclude-filter 子节点： 指定排除那些指定表达式的组件
	
		<context:component-scan base-package="com.baidu.beans.annotation">
			<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
		</context:component-scan>
	 -->
	 
	<!-- 
		context:include-filter 子节点： 指定只包含那些指定表达式的组件 ，
				但是,这是需要配置一个 use-default-filters="false"
	
	-->
	<context:component-scan base-package="com.baidu.beans.annotation" use-default-filters="false">
		<context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
	</context:component-scan>

</beans>

运行结果：

Ⅰ. 基本情况：仅配置基本情况，不添加任何限制条件

<context:component-scan base-package="com.baidu.beans.annotation"></context:component-scan>

运行结果：

com.baidu.beans.annotation.TestObject@f395158
com.baidu.beans.annotation.controller.UserController@7c0b7036
com.baidu.beans.annotation.servlice.UserService@52f428d9
com.baidu.beans.annotation.repository.UserRepositoryImpl@1ba5e91b

Ⅱ. 第一种情况：resource-pattern:指定扫描那个特定包下的资源，其他的子包将不被扫描

	<context:component-scan base-package="com.baidu.beans.annotation"
		resource-pattern="repository/*.class"></context:component-scan>

运行结果： 其他的bean 不被扫描

com.baidu.beans.annotation.repository.UserRepositoryImpl@7a05393a

Ⅲ. 第二种情况：context:exclude-filter 子节点： 指定排除那些指定表达式的组件

<context:component-scan base-package="com.baidu.beans.annotation">
			<context:exclude-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
		</context:component-scan>

运行结果： 当获取UserRepository 时抛出错误

org.springframework.beans.factory.NoSuchBeanDefinitionException: No bean named "userRepository" is defined

com.baidu.beans.annotation.TestObject@3448cbd6
com.baidu.beans.annotation.controller.UserController@173e696b
com.baidu.beans.annotation.servlice.UserService@27afbb9

Ⅹ. 第三种情况：context:include-filter 子节点： 指定只包含那些指定表达式的组件 ，

	<context:component-scan base-package="com.baidu.beans.annotation" use-default-filters="true">
		<context:include-filter type="annotation" expression="org.springframework.stereotype.Repository"/>
	</context:component-scan>

运行结果： 
a. 如果use-default-filters="true"， 则既是配置context:include-filter 还是使用的默认的bean即Ⅰ. 基本情况的配置情况

com.baidu.beans.annotation.TestObject@a54d24d
com.baidu.beans.annotation.controller.UserController@46bac287
com.baidu.beans.annotation.servlice.UserService@f395158
com.baidu.beans.annotation.repository.UserRepositoryImpl@7c0b7036

b. 如果use-default-filters="false"，则 才能使用只包含哪些指定表达式的组件

com.baidu.beans.annotation.repository.UserRepositoryImpl@5a05fffe

AutowiredAnnotationBeanPostProcessor 是bean 的后置处理器

1. 建立持久化类之间的关联关系：

TestObject.java

package com.baidu.beans.annotation;

import org.springframework.stereotype.Controller;

@Controller
public class TestObject {

}

UserController.java

package com.baidu.beans.annotation.controller;

import org.springframework.stereotype.Controller;
import com.baidu.beans.annotation.servlice.UserService;

@Controller
public class UserController {
	
	private UserService userService;
	
	public void execute(){
		System.out.println("UserController execute....");
		userService.add();
	}
}

接口：UserRepository.java

package com.baidu.beans.annotation.repository;

import org.springframework.stereotype.Repository;

@Repository
public interface UserRepository {

	void save();
}

接口：UserRepository 的实现类：UserRepositoryImpl.java

package com.baidu.beans.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import com.baidu.beans.annotation.TestObject;

/**
 * Spring 有默认的命名策略：使用非限定类名，只一个字母小写，
 * 		也可以咋注解中通过vale 属性值标识组件的名称 ,如：@Repository("userRepository")
 */
@Repository
public class UserRepositoryImpl implements UserRepository {
	
	private	TestObject testObject;
	
	public void save() {
		System.out.println("UserRepositoryImpl Save....");
		System.out.println(testObject);
		
	}

}

UserService.java

package com.baidu.beans.annotation.servlice;

import org.springframework.stereotype.Service;

import com.baidu.beans.annotation.repository.UserRepository;

@Service
public class UserService {

	private  UserRepository userRepository;
	
	public void add() {
		System.out.println("UserService add....");
		userRepository.save();
	}
}

配置bean

<?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-4.0.xsd">

	<context:component-scan base-package="com.baidu.beans.annotation"></context:component-scan>

</beans>

测试方法：

package com.baidu.beans.annotation;

import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
import com.baidu.beans.annotation.controller.UserController;

public class TestSpringAnnotationBeans {
	
	public static void main(String[] args) {
		
		ApplicationContext applicationContext = new ClassPathXmlApplicationContext("beans_annotation.xml");
			
		UserController uc = (UserController) applicationContext.getBean("userController");
		System.out.println(uc);
		uc.execute();
	}
}

在上面的基础上运行：

@Autowired 注解自动装配具有兼容类型的单个 Bean属性
           构造器, 普通字段(即使是非 public), 一切具有参数的方法都可以应用@Authwired 注解

(1). 当我们把 @Autowired 分别加到 普通的字段上 

package com.baidu.beans.annotation.servlice;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.baidu.beans.annotation.repository.UserRepository;

@Service
public class UserService {
	
	@Autowired
	private  UserRepository userRepository;
	
	public void add() {
		System.out.println("UserService add....");
		userRepository.save();
	}
}

package com.baidu.beans.annotation.controller;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Controller;

import com.baidu.beans.annotation.servlice.UserService;

@Controller
public class UserController {
	
	@Autowired
	private UserService userService;
	
	public void execute(){
		System.out.println("UserController execute....");
		userService.add();
	}
}

2. 当我们把 @Autowired 分别加到 set方法上

package com.baidu.beans.annotation.servlice;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Service;

import com.baidu.beans.annotation.repository.UserRepository;

@Service
public class UserService {
	
	private  UserRepository userRepository;
	
	@Autowired
	public void setUserRepository(UserRepository userRepository) {
		this.userRepository = userRepository;
	}
	public void add() {
		System.out.println("UserService add....");
		userRepository.save();
	}
}

这是因为IOC容器中有 userRepository. userService 等对应bean ，才可以想上面运行，如果IOC容器没有响应的bean 呢？

package com.baidu.beans.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import com.baidu.beans.annotation.TestObject;

/**
 * Spring 有默认的命名策略：使用非限定类名，只一个字母小写，
 * 		也可以咋注解中通过vale 属性值标识组件的名称 ,如：@Repository("userRepository")
 */
@Repository("userRepository")
public class UserRepositoryImpl implements UserRepository {
	
	@Autowired
	private	TestObject testObject;
	
	public void save() {
		System.out.println("UserRepositoryImpl Save....");
		System.out.println(testObject);
	}
}

去除IOC 容器中的testObject 的bean 

运行结果：

设置：@Autowired(required=false)

package com.baidu.beans.annotation.repository;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.stereotype.Repository;

import com.baidu.beans.annotation.TestObject;

/**
 * Spring 有默认的命名策略：使用非限定类名，只一个字母小写，
 * 		也可以咋注解中通过vale 属性值标识组件的名称 ,如：@Repository("userRepository")
 */
@Repository("userRepository")
public class UserRepositoryImpl implements UserRepository {
	
	@Autowired(required=false)
	private	TestObject testObject;
	
	public void save() {
		System.out.println("UserRepositoryImpl Save....");
		System.out.println(testObject);
	}
}

如果IOC容器中有好几个相匹配的bean 会怎么样呢？

UserJdbcRepository.java 实现UserRepository 接口

package com.baidu.beans.annotation.repository;

import org.springframework.stereotype.Repository;
@Repository
public class UserJdbcRepository implements UserRepository {

	@Override
	public void save() {
		
		System.out.println("UserJdbcRepository save...");
	}
}

运行结果：

为什么没有问题呢？

因为在UserService 中的setUserRepository () 放好有一个实现了被配置了()

如果我们去掉 UserRepositoryImpl 中的userRepository，会怎么样呢？

除了这样配置以外还有下面几种配置方式：