通过代码入门Spring①何为IOC

package cn.podger.spring.demo1;

public class HelloWorld {
private String strSomeThingSay = "helloWorld!";

public String getSomeThingSay(){
System.out.println(strSomeThingSay);
return strSomeThingSay;
}

public void saySomeThing(String str){
strSomeThingSay = str;
System.out.println(strSomeThingSay);
}

}

package cn.podger.spring.demo1;

import org.springframework.context.annotation.Scope;
import org.springframework.stereotype.Component;

@Component
@Scope("prototype")
public class Student {
private String name;
private String id;
private int age = 100;
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getId() {
return id;
}
public void setId(String id) {
this.id = id;
}
public int getAge() {
return age;
}
public void setAge(int age) {
this.age = age;
}

}

package cn.podger.spring.demo1;

import org.springframework.beans.factory.xml.XmlBeanFactory;
import org.springframework.core.io.FileSystemResource;

/**
* Spring  IOC 功能演示  程序中的之间的关系，不用代码控制，而完全是由容器来控制
*
*/
public class App
{
public static void main( String[] args )
{
/**
* FileSystemResource 搜索的是项目工作目录下的地址  本案例为  /spring-demo1文件夹下
*/
XmlBeanFactory xbf = new XmlBeanFactory(new FileSystemResource("applicationContext.xml"));
HelloWorld hw1 = (HelloWorld)xbf.getBean("helloWorld");
hw1.getSomeThingSay();
hw1.saySomeThing("Spring 你好！");

HelloWorld hw2 = (HelloWorld)xbf.getBean("helloWorld");
hw2.getSomeThingSay();
/**
* 输出结果为
* helloWorld!
* Spring 你好！
* Spring 你好！
* 以下关于bean的解析说明了，默认是单例模式，所以以上结果也就能理解了.
* The scope of this bean: typically "singleton" (one shared instance, which will be returned by all calls to
*  getBean with the given id), or "prototype" (independent instance resulting from each call to getBean).
*  Default is "singleton". Singletons are most commonly used, and are ideal for multi-threaded service
*  objects. Further scopes, such as "request" or "session", might be supported by extended bean
*  factories (e.g. in a web environment). Note: This attribute will not be inherited by child bean
*  definitions. Hence, it needs to be specified per concrete bean definition. Inner bean definitions inherit
*  the singleton status of their containing bean definition, unless explicitly specified: The inner bean will
*  be a singleton if the containing bean is a singleton, and a prototype if the containing bean has any
*  other scope.
*/

/**
* 在applicationContext 修改bean为以下
*  <bean id="helloWorld"  scope="prototype" class="cn.podger.spring.demo1.HelloWorld"></bean>
* 也就是添加了个scope="prototype"属性  意思为每次getBean 为new 对象
* 修改后的结果为
* helloWorld!
* Spring 你好！
* helloWorld!
* 根据以上的解析这输出毋容置疑.
*/

/**
* 另外还有种通过spring注解方法加载的方法
* 在配置文件中添加以下内容
* <context:component-scan base-package="cn.podger.spring.demo1"></context:component-scan>
* 意思是扫描@component加载bean
* 同<bean id="" class=""> </bean> 的意思
* 代码如下
*/
/**
*Student student = (Student)xbf.getBean("student");
*System.out.println(student.getAge());
*/
}
}