Spring IoC

  IoC简介

    The Inversion of Control (IoC)  is also known as dependency injection (DI)。

    IOC 容器主要实现实例化具体的Bean和动态装配。

一、注入类型

1、setter

<bean id="exampleBean" class="examples.ExampleBean">

  <!-- setter injection using the nested <ref/> element -->
  <property name="beanOne"><ref bean="anotherExampleBean"/></property>

  <!-- setter injection using the neater 'ref' attribute -->
  <property name="beanTwo" ref="yetAnotherBean"/>
  <property name="integerProperty" value="1"/>
</bean>

<bean id="anotherExampleBean" class="examples.AnotherBean"/>
<bean id="yetAnotherBean" class="examples.YetAnotherBean"/>

 

public class ExampleBean {

    private AnotherBean beanOne;
    private YetAnotherBean beanTwo;
    private int i;

    public void setBeanOne(AnotherBean beanOne) {
        this.beanOne = beanOne;
    }

    public void setBeanTwo(YetAnotherBean beanTwo) {
        this.beanTwo = beanTwo;
    }

    public void setIntegerProperty(int i) {
        this.i = i;
    }    
}

 

2、构造方法

package x.y;

public class Foo {

    public Foo(Bar bar, Baz baz) {
        // ...
    }
}

 

<beans>
    <bean id="foo" class="x.y.Foo">
        <constructor-arg ref="bar"/>
        <constructor-arg ref="baz"/>
    </bean>
</beans>

 

Spring不能确定基本类型的初始值，例如：

package examples;

public class ExampleBean {

    // No. of years to the calculate the Ultimate Answer
    private int years;

    // The Answer to Life, the Universe, and Everything
    private String ultimateAnswer;

    public ExampleBean(int years, String ultimateAnswer) {
        this.years = years;
        this.ultimateAnswer = ultimateAnswer;
    }
}

Spring容器使用，type属性标识简单类型，如：

<bean id="exampleBean" class="examples.ExampleBean">
  <constructor-arg type="int" value="7500000"/>
  <constructor-arg type="java.lang.String" value="42"/>
</bean>

 也可使用inex属性标识，如：

<bean id="exampleBean" class="examples.ExampleBean">
  <constructor-arg index="0" value="7500000"/>
  <constructor-arg index="1" value="42"/>
</bean>

  

3、接口注入

很少使用。

二、bean的属性id与name的区别

name可以使用特殊字符，但id不可以。

 

三、简单属性的注入

package com.gll.spring.ioc.dao;

import com.gll.spring.ioc.model.User;
import com.gll.spring.ioc.service.UserService;

/**
 * Created by Administrator on 2015/4/4.
 */
public class UserDaoImpl implements UserDao {

    private int daoId;

    private String daoStatus;

    @Override
    public boolean save(User user) {
        return true;
    }

    public int getDaoId() {
        return daoId;
    }

    public void setDaoId(int daoId) {
        this.daoId = daoId;
    }

    public String getDaoStatus() {
        return daoStatus;
    }

    public void setDaoStatus(String daoStatus) {
        this.daoStatus = daoStatus;
    }
}

 

    <bean id="userDao" class="com.gll.spring.ioc.dao.UserDaoImpl">
        <property name="daoId" value="10"></property>
        <property name="daoStatus" value="sucess" ></property>
    </bean>

 主要使用spring本身提供的一些bean，例如：

<bean id="myDataSource" class="org.apache.commons.dbcp.BasicDataSource" destroy-method="close">
  
  <!-- results in a setDriverClassName(String) call -->
  <property name="driverClassName" value="com.mysql.jdbc.Driver"/>
  <property name="url" value="jdbc:mysql://localhost:3306/mydb"/>
  <property name="username" value="root"/>
  <property name="password" value="masterkaoli"/>
</bean>