原文链接：http://www.orlion.ga/189/

一、scope

bean的scope属性中常用的有两种：singleton（单例，默认）和prototype(原型，每次创建新对象)

例:beans.xml

<bean id="userService" class="ml.orlion.service.UserService" scope="prototype"><property name="userDao" ref="userDao"/>
</bean>

在java文件中:

BeanFactory appContext = new ClassPathXmlApplicationContext("beans.xml");
UserService userService = (UserService)appContext.getBean("userService");
UserService userServic2 = (UserService)appContext.getBean("userService");
System.out.println(userService == userServic2);// 输出false

二、集合注入

UserDAOImpl.java:

package ml.orlion.dao.impl;import java.util.List;
import java.util.Map;
import java.util.Set;
import ml.orlion.dao.UserDAO;
import ml.orlion.model.User;public class UserDAOImpl implements UserDAO{private Set<String> sets;private List<String> lists;private Map<String , String> maps;public void saveUser(User user){System.out.println("save usering");}public Set<String> getSets() {return sets;}public void setSets(Set<String> sets) {this.sets = sets;}public List<String> getLists() {return lists;}public void setLists(List<String> lists) {this.lists = lists;}public Map<String, String> getMaps() {return maps;}public void setMaps(Map<String, String> maps) {this.maps = maps;}public String toString(){return sets.size() +"|"+ lists.size() +"|"+ maps.size();}
}

beans.xml中配置:

<bean id="userDao" class="ml.orlion.dao.impl.UserDAOImpl"><property name="sets"><set><value>1</value></set></property><property name="lists"><list><value>1</value><value>2</value></list></property><property name="maps"><map><entry key="1" value="1"></entry><entry key="2" value="2"></entry><entry key="3" value="3"></entry></map></property></bean>

然后测试一下:

BeanFactory appContext = new ClassPathXmlApplicationContext("beans.xml");
UserDAO userDao = (UserDAO) appContext.getBean("userDao");
System.out.println(userDao);// 输出 1|2|3

三、自动装配AutoWire

autowire属性有六种值:autodatact、byName、byType、constructor、default、no

byName:按照名字自动去匹配

byType:按照类型自动匹配

UserDAOImpl.java:

package ml.orlion.dao.impl;import ml.orlion.dao.UserDAO;
import ml.orlion.model.User;public class UserDAOImpl implements UserDAO{// 添加id以区分private int daoId;public int getDaoId() {return daoId;}public void setDaoId(int daoId) {this.daoId = daoId;}public void saveUser(User user){System.out.println("save usering");}public String toString(){return "daoId" + daoId;}
}

beans.xml:

<bean id="userDao" class="ml.orlion.dao.impl.UserDAOImpl"><property name="daoId" value="1"></property></bean><bean id="userDao2" class="ml.orlion.dao.impl.UserDAOImpl"><property name="daoId" value="2"></property></bean><bean id="userService" class="ml.orlion.service.UserService" scope="prototype" autowire="byName"></bean>

测试一下：

BeanFactory appContext = new ClassPathXmlApplicationContext("beans.xml");
UserService userService = (UserService) appContext.getBean("userService");
System.out.println(userService.getUserDao());

这时候会输出daoId=1

注:如果所有的bean都用同一种，可以使用beans的属性:defalut-autowire

四、生命周期

1、lazy-init

lazy-init="true"则bean在Ioc容器初始化的时候不进行初始化

注:可以beans标签上设置default-lazy-init="true"

2、init-method(bean初始化的时候执行)、destroy-method(bean销毁的时候执行)

UserService.java

package ml.orlion.service;import ml.orlion.dao.UserDAO;
import ml.orlion.dao.impl.UserDAOImpl;
import ml.orlion.model.User;public class UserService {private UserDAO userDAO = new UserDAOImpl();public void init(){System.out.println("init");}public void destroy(){System.out.println("destroy");}public UserDAO getUserDao() {return userDAO;}public void setUserDao(UserDAO userDAO) {this.userDAO = userDAO;}public void saveUser(User user){this.userDAO.saveUser(user);}
}

beans.xml:

<bean id="userDao" class="ml.orlion.dao.impl.UserDAOImpl"><property name="daoId" value="1"/></bean><bean id="userService" class="ml.orlion.service.UserService" destroy-method="destroy" init-method="init"><property name="userDao" ref="userDao"/></bean>

测试：

ClassPathXmlApplicationContext appContext = new ClassPathXmlApplicationContext("beans.xml");
UserService userService = (UserService) appContext.getBean("userService");
appContext.destroy();// 需要主动调用该方法才会销毁bean

注:scope="prototype"时，调用destroy不会销毁bean。Ioc容器不会管理bean的生命周期