Java利用反射和读取xml实现迷你容器-编程知识

由于需要框架能实现多态，达到控制反转解耦。所以容器还是需要的，容器的存在可以简化对象获取工作，但是容器也不是万能的。合理使用即可，Spring对我来说太庞大了，用不着，为此给框架写一个迷你版容器。

容器配置还是继承以前用spring.net的容器配置，名称为ObjConfig.xml放在程序根目录供容器初始化

<?xml version="1.0" encoding="utf-8"?>
<objects xmlns='http://www.springframework.net' default-autowire="byType"><!--这个配置文件主要用来配置系统的业务服务类，不要删除、修改提交其他人添加的配置，新加配置提交时主要同时提交配置使用的动态库，--><!--否则会造成其他人更新后报错--><!--检验数据访问层底层。postgresql配LIS.DAL.Base.PostgreSqlBase--><object id="LisMianDbFactory" type="LIS.Dal.Base.PostgreSqlBase,LIS.Dal.Base"  singleton="false"></object></objects>

容器实现

package LIS.Core.Context;import org.w3c.dom.Document;
import org.w3c.dom.Element;
import org.w3c.dom.Node;
import org.w3c.dom.NodeList;import javax.xml.parsers.DocumentBuilder;
import javax.xml.parsers.DocumentBuilderFactory;
import java.io.File;
import java.lang.reflect.Type;
import java.net.URL;
import java.net.URLClassLoader;
import java.util.List;
import java.util.HashMap;
import java.util.*;//一个迷你版容器，供ORM等控制反转使用
public class ObjectContainer {///用来存类型private static List<Class> classList=new ArrayList<Class>();///存类的查找关系private static HashMap<String, Integer> classIndexMap = new HashMap<String, Integer>();/// <summary>/// 按类型返回强类型的对象,一般用接口获得实现类/// </summary>/// <typeparam name="T">对象类型</typeparam>/// <returns>返回的对象</returns>public static <T> T GetObject(){Type type = ObjectContainer.class.getClass().getGenericSuperclass();Class c=type.getClass();Class<?> parent=c.getSuperclass();String cName=c.getName();if(classIndexMap.containsKey(cName)){//创建对象Object o = GetObject(cName);return (T)o;}if(parent!=null){String parentName=parent.getName();if(classIndexMap.containsKey(parentName)){//创建对象Object o = GetObject(parentName);return (T)o;}}Class<?> interfaceArr[]=c.getInterfaces();if(interfaceArr!=null&&interfaceArr.length>0){for(int j=0;j<interfaceArr.length;j++){String interfaceName=interfaceArr[j].getName();if(classIndexMap.containsKey(interfaceName)){//创建对象Object o = GetObject(interfaceName);return (T)o;}}}return null;}/// <summary>/// 按名称返回强类型的对象/// </summary>/// <typeparam name="T">对象类型</typeparam>/// <param name="name">对象名称</param>/// <returns>返回的对象</returns>public static <T> T GetTypeObject(String name){Object o=GetObject(name);return (T)o;}/// <summary>/// 按名称返回对象/// </summary>/// <param name="name">对象名称</param>/// <returns>返回对象</returns>public static Object GetObject(String name){if(classIndexMap.containsKey(name)){try {int index=classIndexMap.get(name);Class c=classList.get(index);//创建对象Object o = c.newInstance();return o;}catch (Exception ex){ex.printStackTrace();}}return null;}/// <summary>/// 用类型全名和程序集全名获得类型/// </summary>/// <param name="typeName">类型全名</param>/// <param name="assemblyName">程序集名</param>/// <returns></returns>private static Class GetType(String typeName, String assemblyName){try {//得到根路径Class<?> clazz = ObjectContainer.class;ClassLoader classLoader = clazz.getClassLoader();URL resourceURL1 = classLoader.getResource("");String bashePath = resourceURL1.getFile();//组装成jar包路径String jarPath=bashePath+assemblyName+".jar";File file = new File(jarPath);if (!file.exists()) {throw new Exception("未能找到"+jarPath+"的文件");}//反射得到类型//自己生成jar包路径URL url = file.toURI().toURL();URL[] urls = new URL[]{url};//加载程序集URLClassLoader loader = new URLClassLoader(urls);//加载类Class c = loader.loadClass(typeName);if(c!=null){return  c;}else{throw new Exception("未能构建类型"+typeName);}}catch (Exception ex){ex.printStackTrace();}return  null;}/// <summary>/// 从根目录的ObjConfig初始化IOC容器，还是按Spring.Net的配置格式/// </summary>public static void InitIoc() {try {//得到根路径Class<?> clazz = ObjectContainer.class;ClassLoader classLoader = clazz.getClassLoader();URL resourceURL = classLoader.getResource("resources/ObjConfig.xml");String IocPath = resourceURL.getFile();//判断配置是否存在File file = new File(IocPath);if (!file.exists()) {System.out.println("resources/ObjConfig.xml文件不存在,请确认!");return;}//解析xmlDocumentBuilderFactory factory = DocumentBuilderFactory.newInstance();DocumentBuilder builder = factory.newDocumentBuilder();Document document = builder.parse(file);// 获得根节点Element rootElement = document.getDocumentElement();// 获得根节点下的所有子节点NodeList students = rootElement.getChildNodes();for (int i = 0; i < students.getLength(); i++) {// 由于节点多种类型，而一般我们需要处理的是元素节点Node childNode = students.item(i);// 元素节点就是非空的子节点，也就是还有孩子的子节点if (childNode.getNodeType() == Node.ELEMENT_NODE) {Element childElement = (Element) childNode;//不是对象配置元素就忽略if(childElement.getNodeName()!= "object"){continue;}//解析类型配置String type=childElement.getAttribute("type");//是否单例String singleton=childElement.getAttribute("singleton");//取对象idString id=childElement.getAttribute("id");//分割类全面和包名String [] arr=type.split(",");//反射得到类型Class c=GetType(arr[0],arr[1]);//添加到类型列表classList.add(c);//存储索引int index=classList.size()-1;Class<?> parent=c.getSuperclass();//有id就存id映射if(id!=null&&id!=""){if(classIndexMap.containsKey(id)){throw new Exception("已经包含了id为:"+id+"的类型");}classIndexMap.put(id,index);}//有父类就存父类映射if(parent!=null){String parentName=parent.getName();if(!classIndexMap.containsKey(parentName)){classIndexMap.put(parentName,index);}}//得到所有实现的接口Class<?> interfaceArr[]=c.getInterfaces();//循环存接口映射if(interfaceArr!=null&&interfaceArr.length>0){for(int j=0;j<interfaceArr.length;j++){String interfaceName=interfaceArr[j].getName();if(!classIndexMap.containsKey(interfaceName)) {classIndexMap.put(interfaceName, index);}}}}}}catch (Exception ex) {ex.printStackTrace();}}
}