集合装配
如果bean中有一些集合属性，配置文件的配置如下
package com.bjsxt.dao.impl; import java.util.List;
import java.util.Map;
import java.util.Set; import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User; public class UserDAOImpl implements UserDAO {
/* (non-Javadoc)
* @see com.bjsxt.dao.UserDAO#save(com.bjsxt.model.User)
*/
private Set<String> sets;
private List<String> lists;
private Map<String , String> maps; 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 UserDAOImpl() {
} public void save(User user) {
System.out.println("user saved!");
} @Override
public String toString() {
return "sets size:" + sets.size() + "| lists size:" + lists.size() + "| maps size:" + maps.size() ;
} }
具有集合属性的UserDAOImpl
<?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-2.5.xsd"> <bean name="userDAO" class="com.bjsxt.dao.impl.UserDAOImpl">
<property name="sets">
<set>
<value>1</value>
<value>2</value>
</set>
</property>
<property name="lists">
<list>
<value>1</value>
<value>2</value>
<value>3</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>
<entry key="4" value="4"></entry>
</map>
</property>
</bean> <bean id="userService" class="com.bjsxt.service.UserService">
<!--
<property name="userDAO">
<ref bean="userDAO"/>
</property>
-->
<constructor-arg>
<ref bean="userDAO"/>
</constructor-arg>
</bean> </beans>
配置文件
自动装配
如果每个属性都使用ref配置，一个大项目的Spring配置会十分庞大，可以通过<bean>的autowire属性设置自动装配规则。使用后不需要再用<property>子标签设置该bean的属性、依赖关系。Spring会根据反射，自动寻找符合该条件的属性，设置到该bean属性上。如果autowire设置为byType，将会按照属性的类型自动装配，注意如果找到多个该属性类型的bean，会抛出异常。如果是byName，根据名称自动装配，例如如果bean中有个名为datasource的属性，Spring会把id为datasource的bean设置到该bean中
Bean的生命周期
lazy-init：spring默认的是在启动时创建所有的bean的对象，如果一个项目很大，有500个bean，这些bean会一次性全部加载到内存中，会造成启动速度特别慢，将这个属性设置为true，那么beanfactory在调用getbean方法的时候该bean才会被创建
init-method:bean在实例化之后执行的方法
destroy-method:bean使用完毕后执行的方法
<?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-2.5.xsd"> <bean lazy-init="true" id="u" class="com.bjsxt.dao.impl.UserDAOImpl">
</bean> <bean id="userService" class="com.bjsxt.service.UserService" init-method="init" destroy-method="destroy" scope="singleton">
<!--
<property name="userDAO" ref="u" />
-->
<constructor-arg>
<ref bean="u"/>
</constructor-arg>
</bean> </beans>
配置文件
package com.bjsxt.service;
import com.bjsxt.dao.UserDAO;
import com.bjsxt.model.User; public class UserService { private UserDAO userDAO; public void init() {
System.out.println("init");
} public void add(User user) {
userDAO.save(user);
}
public UserDAO getUserDAO() {
return userDAO;
}
public void setUserDAO(UserDAO userDAO) {
this.userDAO = userDAO;
} public UserService(UserDAO userDAO) {
super();
this.userDAO = userDAO;
} public void destroy() {
System.out.println("destroy");
}
}
UserService
package com.bjsxt.service;
import org.junit.Test;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext; import com.bjsxt.model.User; //Dependency Injection
//Inverse of Control
public class UserServiceTest { @Test
public void testAdd() throws Exception {
ClassPathXmlApplicationContext ctx = new ClassPathXmlApplicationContext("beans.xml"); UserService service = (UserService)ctx.getBean("userService");
UserService service2 = (UserService)ctx.getBean("userService"); ctx.destroy(); } }
单元测试
执行结果
注：因为我们配置文件中bean的scope属性设置为了singleton，表示该对象单例，所以实例化两次其实还是同一个对象，如果改为prototype，会输出两个init，不会执行detroy-method指定的方法，具体原因不明，可以查阅相关资料