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){          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>