最简单的(直接量值)set的注入-IOC-Bean对象属性值注入（依赖注入）

在Spring中对Bean属性赋值的过程我们称之为(值的注入)依赖注入.Spring应用中为Bean的属性注入值的方式有两种,set注入和构造注入,set注入式通过对象的set方法为对象属性赋值,构造注入为通过bean对象的构造方法为属性注入值。

Spring 直接量值的注入:指的是通过Spring IOC为对象的8种基本数据类型，8种基本数据类型对应的封装类以及String类型,日期类型的属性注入值。

反射让不可访问的方法变成可被访问的

    private OpenDataSource() {
        System.out.println("OpenDataSource.OpenDataSource()");
    }

构造方法可以私有

package utils;
/**
 * 模拟数据源对象
 * @author Administrator
 *javax.sql.DataSource
 *模拟写一个开源的连接池
 *如何将此对象交给Spring管理
 *1)以xml的方式对此对象进行描述(在配置文件中以<bean>标签描述)
 *2)以注解的方式对此对象进行描述
 */
public class OpenDataSource {
    private String driverClassName;
    private String url;
    private String userName;
    private String password;
    //为属性赋值的过程叫值的注入，也叫依赖注入，通过调用对象的set方法赋值
    public OpenDataSource() {
        System.out.println("OpenDataSource.OpenDataSource()");
    }
    
    public void init(){
        System.out.println("OpenDataSource.init()");
    }
    public void close(){
        System.out.println("OpenDataSource.destory()");
    }
    
    public String getDriverClassName() {
        return driverClassName;
    }
    public void setDriverClassName(String driverClassName) {
        this.driverClassName = driverClassName;
    }
    public String getUrl() {
        return url;
    }
    public void setUrl(String url) {
        this.url = url;
    }
    public String getUserName() {
        return userName;
    }
    public void setUserName(String userName) {
        this.userName = userName;
    }
    public String getPassword() {
        return password;
    }
    public void setPassword(String password) {
        this.password = password;
    }

    @Override
    public String toString() {
        return "OpenDataSource [driverClassName=" + driverClassName + ", url=" + url + ", userName=" + userName
                + ", password=" + password + "]";
    }
    
}

<beans
    xmlns="http://www.springframework.org/schema/beans" xmlns:p="http://www.springframework.org/schema/p"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:context="http://www.springframework.org/schema/context"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:mvc="http://www.springframework.org/schema/mvc" xmlns:util="http://www.springframework.org/schema/util"
    xmlns:jpa="http://www.springframework.org/schema/data/jpa"
    xsi:schemaLocation="  
       http://www.springframework.org/schema/beans   
       http://www.springframework.org/schema/beans/spring-beans-4.3.xsd  
       http://www.springframework.org/schema/mvc   
       http://www.springframework.org/schema/mvc/spring-mvc-4.3.xsd   
       http://www.springframework.org/schema/tx   
       http://www.springframework.org/schema/tx/spring-tx-4.3.xsd   
       http://www.springframework.org/schema/aop 
       http://www.springframework.org/schema/aop/spring-aop-4.3.xsd
       http://www.springframework.org/schema/util 
       http://www.springframework.org/schema/util/spring-util-4.3.xsd
       http://www.springframework.org/schema/data/jpa 
       http://www.springframework.org/schema/data/jpa/spring-jpa-1.3.xsd
       http://www.springframework.org/schema/context
       http://www.springframework.org/schema/context/spring-context-4.3.xsd">
    <!--如何理解spring中的Bean对象:由spring框架管理的所有对象都是bean对象 -->
    <!-- Bean对象何时创建？要看对象是否配置延迟加载 -->
    <!-- Bean对象的默认作用域singleton(默认在内存中只有一份) -->
    <!-- 单例对象是何时销毁的？容器关闭时销毁 -->
    <bean id="openDataSource" 
    class="utils.OpenDataSource"
        init-method="init" 
        destroy-method="close"
         lazy-init="false" 
         scope="singleton">
         <!--  系统底层创建对象后对调用property元素中name属性值，即对象的set方法为属性赋值-->
        <property name="DriverClassName" value="com.mysql.jdbc.driver"></property>
        <property name="Url" value="jdbc:///test"></property>
        <property name="UserName" value="root"></property>
        <property name="Password" value="123456"></property>
    </bean>
</beans>

package test;

import org.junit.After;
import org.junit.Before;
import org.springframework.context.support.ClassPathXmlApplicationContext;

public class TestBase {
    protected ClassPathXmlApplicationContext ctx;
    @Before
    public void init(){
        ctx=new ClassPathXmlApplicationContext("spring-configs.xml");
    }
    @After
    public void close(){
        ctx.close();
    }
}

package test;

import org.junit.Assert;
import org.junit.Test;

import utils.OpenDataSource;

public class TestDataSource01 extends TestBase{
    @Test
    public void testOpenDataSource(){
        //获取bean对象
        OpenDataSource ds = ctx.getBean(OpenDataSource.class);
        //测试对象值是否为空
        Assert.assertNotEquals(null, ds);
        System.out.println(ds);
    }
}