自己实现的Spring IOC容器

矫情吗；* 2022-06-18 02:57 247阅读 0赞

该容器需要借助于Dom4jJar包来解析XML文件。

package com.lanp.myioc;

/\*\*  
 \* 输出接口  
 \* @author LanP  
 \*/  
public interface Output \{  
 /\*\*  
  \* 获取输出消息  
  \* @param msg  
  \* @return String  
  \*/  
 String getMsg(String msg);  
   
 void out();  
\}

package com.lanp.myioc;

/\*\*  
 \* 带缓存的打印机  
 \* @author LanP  
 \*/  
public class BuffPrinter implements Output \{  
   
 private static final int MAX\_SIZE = 1024;  
 private StringBuffer\[\] printMsg = new StringBuffer\[MAX\_SIZE \* 2\];  
 /\*\*  
  \* 记录当前打印的作用位置  
  \*/  
 private int msgNum = 0;  
   
   
 @Override  
 public String getMsg(String msg) \{  
  if(msgNum >= MAX\_SIZE)\{  
   System.out.println("输出管道队列已满，添加失败！");  
  \} else \{  
   printMsg\[msgNum++\] = new StringBuffer(msg);  
  \}  
     
  return msg;  
 \}

@Override  
 public void out() \{  
  //只要尚有作用没有打印就继续打印  
  while(msgNum > 0) \{  
   System.out.println("缓存打印机打印： " + printMsg\[0\].toString());  
   //将作业队列向前移一位，剩下的作业书量减一  
   System.arraycopy(printMsg, 1, printMsg, 0, --msgNum);  
  \}  
 \}  
   
\}

package com.lanp.myioc;

/\*\*  
 \* 普通打印机类,实现了输出接口  
 \* @author LanP  
 \*/  
public class Printer implements Output \{  
   
 private static final int MAX\_SIZE = 1024;  
 private String\[\] printMsg = new String\[MAX\_SIZE\];  
 /\*\*  
  \* 记录当前打印的作用位置  
  \*/  
 private int msgNum = 0;  
   
   
 @Override  
 public String getMsg(String msg) \{  
  if(msgNum >= MAX\_SIZE)\{  
   System.out.println("输出管道队列已满，添加失败！");  
  \} else \{  
   printMsg\[msgNum++\] = msg;  
  \}  
     
  return msg;  
 \}

@Override  
 public void out() \{  
  //只要尚有作用没有打印就继续打印  
  while(msgNum > 0) \{  
   System.out.println("普通打印机打印： " + printMsg\[0\]);  
   //将作业队列向前移一位，剩下的作业书量减一  
   System.arraycopy(printMsg, 1, printMsg, 0, --msgNum);  
  \}  
 \}  
   
\}

package com.lanp.myioc;

/\*\*  
 \* 计算机实例，具有打印机  
 \* @author LanP  
 \* @version V1.0  
 \*/  
public class Computer \{  
 private String name;  
 public void setName(String name) \{  
  this.name = name;  
 \}

private Output output;  
   
 public void setOutput(Output output) \{  
  this.output = output;  
 \}

public Computer() \{  
    
 \}  
   
 public Computer(Output output) \{  
  this.output = output;  
 \}  
   
 /\*\*  
  \* 模拟消息输入的方法  
  \* @param msg  
  \*/  
 public void msgIn(String msg) \{  
  this.output.getMsg(msg);  
 \}  
   
 /\*\*  
  \* 模拟打印  
  \*/  
 public void print() \{  
  output.out();  
 \}  
\}

<?xml version="1.0" encoding="UTF-8"?>  
<beans>  
 <bean id="computer" class="com.lanp.myioc.Computer">  
  <property name="name" value="飘飘电脑" />  
  <property name="output" ref="buffPrinter" />  
 </bean>  
   
 <bean id="printer" class="com.lanp.myioc.Printer"/>  
 <bean id="buffPrinter" class="com.lanp.myioc.BuffPrinter"/>  
 <bean id="nowtime" class="java.util.Date" scope="prototype" />  
</beans>

package com.lanp.myioc;

/\*\*  
 \* 应用程序容器接口  
 \* @author LanP  
 \*/  
public interface MyApplicationContext \{  
 /\*\*  
  \* 获取指定Bean实例的方法  
  \* @param name  
  \* @return Object  
  \* @throws Exception  
  \*/  
 Object getBean(String name) throws Exception;  
\}

package com.lanp.myioc;

import java.io.File;  
import java.lang.reflect.Method;  
import java.util.Collections;  
import java.util.HashMap;  
import java.util.Map;

import org.dom4j.Document;  
import org.dom4j.Element;  
import org.dom4j.io.SAXReader;

/\*\*  
 \* 应用程序上下文容器实现类  
 \* @author LanP  
 \* @version V1.0  
 \*/  
public class MyXmlApplicationContext implements MyApplicationContext \{  
 /\*\*  
  \* 保存容器中所以单例模式的Bean实例  
  \*/  
 private Map<String,Object> objPool = Collections.synchronizedMap(new HashMap<String,Object>());  
 /\*\*  
  \* 保存配置文件对于的Document对象  
  \*/  
 private Document document;  
 /\*\*  
  \* 保存配置文件中的根元素  
  \*/  
 private Element root;  
   
 public MyXmlApplicationContext(String filePath) throws Exception \{  
  SAXReader reader = new SAXReader();  
  document = reader.read(new File(filePath));  
  root = document.getRootElement();  
  initPool();  
  initProp();  
 \}  
   
 /\*\*  
  \* 初始化容器中的属性  
  \* @throws Exception  
  \*/  
 @SuppressWarnings("unchecked")  
 private void initProp() throws Exception \{  
  //遍历配置文件里的每个<bean>标签  
  for(Object obj:root.elements()) \{  
   Element beanElement = (Element)obj;  
   //取得bean元素中的ID  
   String beanId = beanElement.attributeValue("id");  
   //取得bean元素中的scope  
   String beanScope = beanElement.attributeValue("scope");  
   //如果Bean标签中的scope不存在或为singleton  
   if(null == beanScope || beanScope.equals("singleton")) \{  
    //取出objPool中的bean实例  
    Object bean = objPool.get(beanId);  
    //遍历Bean元素中的每个property  
    for(Object prop: beanElement.elements()) \{  
     Element propElement = (Element)prop;  
     //取得property元素的name  
     String propName = propElement.attributeValue("name");  
     //取得property元素的value  
     String propValue = propElement.attributeValue("value");  
     //取得property元素的ref  
     String propRef = propElement.attributeValue("ref");  
     //将属性名首字母大写  
     String propNameUpCase = propName.substring(0,1).toUpperCase()  
      + propName.substring(1, propName.length());  
     //如果property元素的value存在  
     if(null != propValue && propValue.length() > 0) \{  
      //获取设置注入的set方法  
      Method setter = bean.getClass().getMethod("set" + propNameUpCase, String.class);  
      //执行set注入  
      setter.invoke(bean, propValue);  
     \}  
       
     if(null != propRef && propRef.length() > 0) \{  
      //取出需要依赖注入的bean实例  
      Object target = objPool.get(propRef);  
      //objPool不存在指定的实例  
      if(null == target) \{  
       System.out.println("不存在你要注入的bean实例");  
      \}  
      //定义设值注入所需的set方法  
      Method setter = null;  
      //遍历target对象实现的所有接口  
      for(Class superInterface : target.getClass().getInterfaces()) \{  
       try \{  
        //获取设值注入所需的setter方法  
        setter = bean.getClass().getMethod("set" + propNameUpCase,superInterface);  
        //如果成功获得该接口对应的方法，直接跳出循环  
        break;  
       \} catch (Exception e) \{  
        //如果没有找到对应的setter方案，继续下次循环  
        continue;  
       \}  
      \}  
      //如果setter方法依然为null  
      //则直接获得target实现类对应的setter方法  
      if(null == setter) \{  
       setter = bean.getClass().getMethod("set" + propNameUpCase, target.getClass());  
      \}  
      //执行setter注入  
      setter.invoke(bean, target);  
     \}  
    \}  
   \}  
  \}  
 \}  
   
 /\*\*  
  \* 初始化容器中所有的单例bean  
  \* @throws Exception  
  \*/  
 private void initPool() throws Exception \{  
  //遍历配置文件里面的每个<bean>标签  
  for(Object obj:root.elements()) \{  
   Element beanElement = (Element)obj;  
   //取得Bean元素的Id  
   String beanId = beanElement.attributeValue("id");  
   //取得Bean元素的class  
   String beanClass = beanElement.attributeValue("class");  
   //取得bean元素的scope  
   String beanScope = beanElement.attributeValue("scope");  
   if(null == beanScope || beanScope.equals("singleton")) \{  
    //模拟构造器创建Bean实例，并将其实例放进objPool  
    objPool.put(beanId, Class.forName(beanClass).newInstance());  
   \} else \{  
    //对于非单例的配置，将其bean类名放进objPool  
    objPool.put(beanId, beanClass);  
   \}  
  \}  
 \}  
   
 /\*\*  
  \* 获取bean实例  
  \*/  
 @Override  
 public Object getBean(String name) throws Exception \{  
  Object target = objPool.get(name);  
  //对于单例bean，容器已经初始化了所有bean实例  
  if(target.getClass() != String.class) \{  
   return target;  
  \} else \{  
   String clazz = (String)target;  
   //对于prototype并未注入属性值  
   return Class.forName(clazz).newInstance();  
  \}  
 \}

package com.lanp.myioc;

public class MyIocTest \{

/\*\*  
  \* 容器工厂的测试类  
  \* @param args  
  \*/  
 public static void main(String\[\] args) throws Exception \{  
  //创建IOC容器  
  MyApplicationContext myApplicationContext = new MyXmlApplicationContext("D:\\\\lanp\\\\lanp\\\\eclipse\\\\my\_workspace\\\\MyDesModPro\\\\src\\\\com\\\\lanp\\\\myioc\\\\bean.xml");  
  //从IOC容器中取出Computer Bean  
  Computer computer = (Computer)myApplicationContext.getBean("computer");  
  //测试Computer对象  
  computer.msgIn("飘");  
  computer.msgIn("飘飘");  
  computer.print();  
  System.out.println(myApplicationContext.getBean("nowtime"));  
 \}