最简单的模拟spring ioc中的scope

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发布时间：2022-12-26 11:11:41 321

相关标签： # java# spring# java# 容器

在spring mvc中，scope主要是prototype和singleton两个状态了，下面用代码简单模拟下：

实体类：

public class BeanDefined {
  
  private String beanId;
  private String classPath;
  private String scope ="singleton";
  
  
  public String getScope() {
    return scope;
  }
  public void setScope(String scope) {
    this.scope = scope;
  }
  public String getBeanId() {
    return beanId;
  }
  public void setBeanId(String beanId) {
    this.beanId = beanId;
  }
  public String getClassPath() {
    return classPath;
  }
  public void setClassPath(String classPath) {
    this.classPath = classPath;
  }
  
  

}

BeanDefined.java,这个类中，存放的是要加入的每个类的名字和全路径，方便容器反射的时候找到：

public class BeanDefined {
  
  private String beanId;
  private String classPath;
  private String scope ="singleton";
。。。。。。。。。

}

模拟的Beanfactory类：

public class BeanFactory {
  
     private List beanDefinedList;
     private Map SpringIoc;//已经创建好实例对象

  public List getBeanDefinedList() {
    return beanDefinedList;
  }

  
  
  
  public BeanFactory(List beanDefinedList) throws Exception {
    
    this.beanDefinedList = beanDefinedList;
    SpringIoc  = new HashMap(); //所有scope="singleton" 采用单类模式管理bean对象
    for(BeanDefined beanObj:this.beanDefinedList){
      if("singleton".equals(beanObj.getScope())){
        Class classFile= Class.forName(beanObj.getClassPath());
        Object instance= classFile.newInstance();
        SpringIoc.put(beanObj.getBeanId(), instance);
      }
    }
    
  }




  public void setBeanDefinedList(List beanDefinedList) {
    this.beanDefinedList = beanDefinedList;
  }
  
  public Object getBean(String beanId) throws Exception{
       Object instance = null;
       for(BeanDefined beanObj:beanDefinedList){
           if(beanId.equals(beanObj.getBeanId())){
             String classPath = beanObj.getClassPath();            
           Class classFile= Class.forName(classPath);
           String scope=beanObj.getScope();
           if("prototype".equals(scope)){//.getBean每次都要返回一个全新实例对象
              
              instance= classFile.newInstance();
           }else{
             instance=SpringIoc.get(beanId);
           }
           return instance;
           }
       }
       return null;
  }
     

}

可以看到，这里通过HASHMAP存放每次要实例化的对象了，使用方法比较简单：

public static void main(String[] args) throws Exception {
    
      //1.声明注册bean
      BeanDefined beanObj = new BeanDefined();
      beanObj.setBeanId("teacher");
      beanObj.setClassPath("com.kaikeba.beans.Teacher");
      beanObj.setScope("prototype");
      
      List beanList = new ArrayList();
      beanList.add(beanObj);//spring核心配置
      
      //2.声明一个Spring提供BeanFacotory
      BeanFactory factory = new BeanFactory(beanList);
     
      
      //3.开发人员向BeanFactory索要实例对象.
      Teacher t= (Teacher) factory.getBean("teacher");
      System.out.println("t="+t);
      Teacher t2= (Teacher) factory.getBean("teacher");
      System.out.println("t2="+t2);

  }

文章来源： https://blog.51cto.com/u_14230175/5910654

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