注入对象

需求：

一个类包含另一个类。（ModelTest的一个字段为HelloWorld对象）
对ModelTest对象，注入一个HelloWorld对象

创建文件：

1.创建com.tutorialspoint包
2.创建HelloWorld类
3.创建MainAPP主类（void main）
4.创建Beans.xml
5.ModelTest类

代码：

HelloWorld.java

package com.tutorialspoint;
public class HelloWorld {
    private String message;
    public void setMessage(String message){
        this.message  = message;
    }
    public void getMessage(){
        System.out.println("Your Message : " + message);
    }
}

MainApp.java

package com.tutorialspoint;
import org.springframework.context.ApplicationContext;
import org.springframework.context.support.ClassPathXmlApplicationContext;
public class MainApp {
    public static void main(String[] args) {
        // TODO Auto-generated method stub
        ApplicationContext context = 
                 new ClassPathXmlApplicationContext("Beans.xml");
          HelloWorld obj = (HelloWorld) context.getBean("helloWorld");
          obj.getMessage();
          ModelTest model = (ModelTest) context.getBean("test");
          model.getStr();
          model.getHelloWorld();
    }
}

Bean.xml

<?xml version="1.0" encoding="UTF-8"?>
<beans xmlns="http://www.springframework.org/schema/beans"
    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:aop="http://www.springframework.org/schema/aop"
    xmlns:tx="http://www.springframework.org/schema/tx" xmlns:context="http://www.springframework.org/schema/context"
    xsi:schemaLocation="
   http://www.springframework.org/schema/beans 
   http://www.springframework.org/schema/beans/spring-beans-3.0.xsd
   http://www.springframework.org/schema/aop 
   http://www.springframework.org/schema/aop/spring-aop-3.0.xsd
   http://www.springframework.org/schema/tx 
   http://www.springframework.org/schema/tx/spring-tx-3.0.xsd
   http://www.springframework.org/schema/context      
   http://www.springframework.org/schema/context/spring-context-3.0.xsd">
    <bean id="helloWorld" name="hello" class="com.tutorialspoint.HelloWorld">
       <property name="message" value="Hello World!"/>
   </bean>
    <bean id="test" class="com.tutorialspoint.ModelTest">
       <property name="str" value="Hello Str!"/>
       <property name="helloWorld" ref="helloWorld"/>
   </bean>
</beans>

ModelTest.java

package com.tutorialspoint;
public class ModelTest {
    private String str;
    private HelloWorld helloWorld;
    public void setStr(String string){
        this.str  = string;
    }
    public void getStr(){
        System.out.println("Your str : " + str);
    }
    public void setHelloWorld(HelloWorld helloworld){
        this.helloWorld  = helloworld;
    }
    public void getHelloWorld(){
        helloWorld.getMessage();
    }
}

运行结果

要点：

ref引用的可以是name也可以是id。