Spring学习文档_IOC配置与应用

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#spring #ioc #文档 #bean #autowired #lucene

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本文详细介绍了Spring框架中的依赖注入概念及其实现方式，包括XML配置和注解方式下的setter注入、构造器注入以及自动装配等内容，并对不同注入方式的特点进行了对比。

控制反转(IOC Inversion of Control)

依赖注入(Dependency Injection)

Samples:http://blog.springsource.com

采用XML

1. 注入类型

setter（重要）
<property name="userDAO" ref="userDao" />
构造方法（有印象就好）
<constructor-arg ref="userDao" />

2. id vs. name -- id和name的意义相同.但是name可以用特殊字符

<bean name="userService" class="com.lohamce.service.UserServiceImpl"></bean>
<bean id="userService" class="com.lohamce.service.UserServiceImpl"></bean>

3. 简单属性的注入

<property name=… value=….>

4. <bean 中的scope属性

singleton 单例 (默认情况下就是该属性)

proptotype 每次创建新的对象, 使用很少

5. 集合注入 collections 将一些属性放到一个集合里面, 很少用

6. 自动装配, 有一定的用处, 可以省略配置property,如果使用annotation,就会用到byType

byName: 根据属性名去查找

byType: 根据对象类型查找

如果所有的bean都用同一种，可以使用beans的属性：default-autowire 进行统一配置

7. 生命周期

lazy-init: 懒加载

init-method destroy-methd 不要和prototype一起用

采用Annotation: IOC的方面,Annotation比xml更方便

1. Annotation第一步：查阅文档 Annotation-based configuration

修改beans.xml

<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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">
	<context:annotation-config />

2. @Autowired

默认按类型by type

<?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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config />
  <bean id="u" class="com.lohamce.dao.impl.UserDAOImpl" />
	
  <bean name="userService" class="com.lohamce.service.impl.UserServiceImpl" />
  
</beans>

package com.lohamce.service.impl;

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

import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;
import com.lohamce.service.UserService;

public class UserServiceImpl implements UserService {
	private UserDAO userDAO;

	@Override
	public void add(User user) {
		userDAO.save(user);
	}

	public UserDAO getUserDAO() {
		return userDAO;
	}

	@Autowired
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

如果想用byName，使用@Qulifier, 如果写在set上，@qualifier需要写在参数上

<?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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

<context:annotation-config />
  <bean name="u2" class="com.lohamce.dao.impl.UserDAOImpl" />
	
  <bean name="userService" class="com.lohamce.service.impl.UserServiceImpl" />
  
</beans>

package com.lohamce.service.impl;

import org.springframework.beans.factory.annotation.Autowired;
import org.springframework.beans.factory.annotation.Qualifier;

import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;
import com.lohamce.service.UserService;

public class UserServiceImpl implements UserService {
	private UserDAO userDAO;

	@Override
	public void add(User user) {
		userDAO.save(user);
	}

	public UserDAO getUserDAO() {
		return userDAO;
	}

	@Autowired
	public void setUserDAO(@Qualifier("u2")UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

3. @Resource（重要）,用到JSR-250, 现在是jcp (Java Community Press)来定制标准等

a) 加入：j2ee/common-annotations.jar

b) 默认byName查找，如果没有查找到,则byType

c) 可以指定特定名称

package com.lohamce.service.impl;

import javax.annotation.Resource;


import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;
import com.lohamce.service.UserService;

public class UserServiceImpl implements UserService {
	private UserDAO userDAO;

	@Override
	public void add(User user) {
		userDAO.save(user);
	}

	public UserDAO getUserDAO() {
		return userDAO;
	}

	@Resource
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

4. @Component @Service @Controller @Repository,2.5.6版本上这四个annotation没有区别，用了这4个annotation的可以被用作resource

<context:component-scan base-package="***.***">

a) 初始化的名字默认为类名首字母小写

b) 可以指定初始化bean的名字

Component: 和Resource标签成套实用, 在注册Component的时候需要把名字写上

<?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-2.5.xsd
           http://www.springframework.org/schema/context
           http://www.springframework.org/schema/context/spring-context-2.5.xsd">

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

package com.lohamce.service.impl;

import javax.annotation.Resource;


import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;
import com.lohamce.service.UserService;
@Component("userService")
public class UserServiceImpl implements UserService {
	private UserDAO userDAO;

	@Override
	public void add(User user) {
		userDAO.save(user);
	}

	public UserDAO getUserDAO() {
		return userDAO;
	}

	@Resource(name="userDAO")
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

package com.lohamce.dao.impl;

import org.springframework.stereotype.Component;

import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;

@Component("userDAO")
public class UserDAOImpl implements UserDAO {

	public void save(User user) {
		System.out.println("user saved!");
	}

}

5. @Scope,默认singleton

package com.lohamce.service.impl;

import javax.annotation.Resource;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;


import com.lohamce.dao.UserDAO;
import com.lohamce.model.User;
import com.lohamce.service.UserService;

@Scope("prototype")
@Component("userService")
public class UserServiceImpl implements UserService {
	private UserDAO userDAO;

	@Override
	public void add(User user) {
		userDAO.save(user);
	}

	public UserDAO getUserDAO() {
		return userDAO;
	}

	@Resource(name="userDao")
	public void setUserDAO(UserDAO userDAO) {
		this.userDAO = userDAO;
	}
}

6. @PostConstruct = init-method; @PreDestroy = destroy-method;

Bean Scope(重要),参见文档:Bean Scope

Table 4.3. Bean scopes

Scope Description

singleton

(Default) Scopes a single bean definition to a single object instance per Spring IoC container.

prototype

Scopes a single bean definition to any number of object instances.

request

Scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring ApplicationContext.

session

Scopes a single bean definition to the lifecycle of an HTTP Session. Only valid in the context of a web-aware Spring ApplicationContext.

global session

Scopes a single bean definition to the lifecycle of a global HTTP Session. Typically only valid when used in a portlet context. Only valid in the context of a web-aware SpringApplicationContext.

Scope	Description
singleton	(Default) Scopes a single bean definition to a single object instance per Spring IoC container.
prototype	Scopes a single bean definition to any number of object instances.
request	Scopes a single bean definition to the lifecycle of a single HTTP request; that is, each HTTP request has its own instance of a bean created off the back of a single bean definition. Only valid in the context of a web-aware Spring `ApplicationContext`.
session	Scopes a single bean definition to the lifecycle of an HTTP `Session`. Only valid in the context of a web-aware Spring `ApplicationContext`.
global session	Scopes a single bean definition to the lifecycle of a global HTTP `Session`. Typically only valid when used in a portlet context. Only valid in the context of a web-aware Spring`ApplicationContext`.