Spring的注入类型(Injection type of Spring)

Set injection

Constructor injection

Static factory method injection

Instance factory method injection

refer：http://blessht.iteye.com/blog/1162131

In the usual java development，a method for programmer to relay on other classes in a class，

is usually a new dependent class to call the class instance method，this development model is the problem of new class instance is not a unified management，Spring put forward the idea of dependency injection.

Set Injection

package com.bless.springdemo.action;
public class SpringAction {
//注入对象springDao
private SpringDao springDao;
//一定要写被注入对象的set方法
public void setSpringDao(SpringDao springDao) {
this.springDao = springDao;
}

public void ok(){
springDao.ok();
}
}

Configuration in XML

<!--配置bean,配置后该类由spring管理-->
<bean name="springAction" class="com.bless.springdemo.action.SpringAction">
<!--(1)依赖注入,配置当前类中相应的属性-->
<property name="springDao" ref="springDao"></property>
</bean>
<bean name="springDao" class="com.bless.springdemo.dao.impl.SpringDaoImpl"></bean>

Constructor injection

public class SpringAction {
//注入对象springDao
private SpringDao springDao;
private User user;

public SpringAction(SpringDao springDao,User user){
4000

this.springDao = springDao;
this.user = user;
System.out.println("构造方法调用springDao和user");
}

public void save(){
user.setName("卡卡");
springDao.save(user);
}
}

Configuration in XML

<bean name="springAction" class="com.bless.springdemo.action.SpringAction">
<!--(2)创建构造器注入,如果主类有带参的构造方法则需添加此配置-->
<constructor-arg ref="springDao"></constructor-arg>
<constructor-arg ref="user"></constructor-arg>
</bean>
<bean name="springDao" class="com.bless.springdemo.dao.impl.SpringDaoImpl"></bean>
<bean name="user" class="com.bless.springdemo.vo.User"></bean>

****When the constructor has many parameters of the same type，bean does not known the descendants of the order of the parameters.

<bean name="springAction" class="com.bless.springdemo.action.SpringAction">
<constructor-arg index="0" ref="springDao"></constructor-arg>
<constructor-arg index="1" ref="user"></constructor-arg>
</bean>
<bean name="springDao" class="com.bless.springdemo.dao.impl.SpringDaoImpl"></bean>
<bean name="user" class="com.bless.springdemo.vo.User"></bean>

Static factory method injection

package com.bless.springdemo.factory;

import com.bless.springdemo.dao.FactoryDao;
import com.bless.springdemo.dao.impl.FactoryDaoImpl;
import com.bless.springdemo.dao.impl.StaticFacotryDaoImpl;

public class DaoFactory {
//静态工厂
public static final FactoryDao getStaticFactoryDaoImpl(){
return new StaticFacotryDaoImpl();
}
}

public class SpringAction {
//注入对象
private FactoryDao staticFactoryDao;

public void staticFactoryOk(){
staticFactoryDao.saveFactory();
}
//注入对象的set方法
public void setStaticFactoryDao(FactoryDao staticFactoryDao) {
this.staticFactoryDao = staticFactoryDao;
}
}

Configuration in XML

<!--配置bean,配置后该类由spring管理-->
<bean name="springAction" class="com.bless.springdemo.action.SpringAction" >
<!--(3)使用静态工厂的方法注入对象,对应下面的配置文件(3)-->
<property name="staticFactoryDao" ref="staticFactoryDao"></property>
</property>
</bean>
<!--(3)此处获取对象的方式是从工厂类中获取静态方法-->
<bean name="staticFactoryDao" class="com.bless.springdemo.factory.DaoFactory" factory-method="getStaticFactoryDaoImpl"></bean>

Instance factory method injection

public class DaoFactory {
//实例工厂
public FactoryDao getFactoryDaoImpl(){
return new FactoryDaoImpl();
}
}

public class SpringAction {
//注入对象
private FactoryDao factoryDao;

public void factoryOk(){
factoryDao.saveFactory();
}

public void setFactoryDao(FactoryDao factoryDao) {
this.factoryDao = factoryDao;
}
}

Configuration in XML

<!--配置bean,配置后该类由spring管理-->
<bean name="springAction" class="com.bless.springdemo.action.SpringAction">
<!--(4)使用实例工厂的方法注入对象,对应下面的配置文件(4)-->
<property name="factoryDao" ref="factoryDao"></property>
</bean>

<!--(4)此处获取对象的方式是从工厂类中获取实例方法-->
<bean name="daoFactory" class="com.bless.springdemo.factory.DaoFactory"></bean>
<bean name="factoryDao" factory-bean="daoFactory" factory-method="getFactoryDaoImpl"></bean>