spring 依赖注入的方式

构造器注入

public CatDaoImpl(String message){
    this.message = message;
}

<bean id="catDaoImpl" class="com.CatDaoImpl">
	<constructor-age value="message"></constructor-age>
</bean>

setter方法注入

public class Id{
    private int id;
    public int getId(){
        return id;
    }
    public void setId(int id){
        this.id = id;
    }
}

<bean id="id" class="com.id">
	<property name="id" value="123"></property>
</bean>

静态工厂注入

顾名思义，就是通过调用静态工厂的方法来获取自己需要的对象，为了让，spring管理所有对象，我们不能直接通过“工厂类.静态方法”来获取对象，而是依然通过spring注入的形式获取

//静态工厂
public class DaoFactory{
    public static final FactoryDao getStaticFactoryDaoImpl(){
        return new StaticFacotryDaoImpl();
    }
}
public class SpringAction{
	private FactoryDao staticFactoryDao; //注入对象
    public void setStaticFactoryDao(FactoryDao staticFactoryDao){
        this.staticFactoryDao = staticFactoryDao;
    }
}

<!-- factory-method：指定使用哪个工厂方法 -->
<bean name="staticFactoryDao" class="com.DaoFactory" 
      factory-method="getStaticFactoryDaoImpl"></bean>

<bean name="springAction" class="com.SpringAction">
	<property name="staticFactoryDao" ref="staticFactoryDao"></property>
</bean>

实例工厂

实例工厂的意思是获取对象实例的方法不是静态的，所以你需要首先new工厂类，再调用普通的实例方法

//实例工厂
public class DaoFactory{
    public FactoryDao getFactoryDaoImpl(){
        return new FactoryDaoImpl();
    }
}
public class SpringAction{
    private FactoryDao factoryDao;
    public void setFactoryDao(FactoryDao factoryDao){
        this.factoryDao = factoryDao;
    }
}

<bean name="daoFactory" class="com.DaoFactory"></bean>
<bean name="factoryDao"
      factory-bean="daoFactory"
      factory-method="getFactoryDaoImpl"></bean>

<bean name="springAction" class="com.SpringAction">
	<property name="factoryDao" ref="factoryDao"></property>
</bean>