夜谭spring的运行原理

众所周知，spring最著名的就是依赖注入，闲暇之际我思考spring的运行原理，文中有一问题尚未解决，希望各路高手指点迷津。

下面是我模拟spring的运行原理写的一个程序，希望对大家有用!

首先跟大家分享框架结构图：

第一步，创建配置管理器

第二步，创建配置文件

第三步，读取配置文件

第四步，实例化对象

第五步，注入

下面请大家跟我看一下类文件

BeansConfig的dtd文件

<!ELEMENT beans (bean*)><!ELEMENT bean (property*)><!ATTLIST beanid CDATA #REQUIREDclass CDATA #REQUIRED><!ELEMENT property EMPTY><!ATTLIST propertyname CDATA #REQUIREDvalue CDATA ""ref CDATA "">

Bean类文件

package com.huan.frame;import java.util.*;public class Bean {private String id;private String className;private List<Property> proList = new ArrayList<Property>();public void aadProperty(Property property){proList.add(property);}public List<Property> getPropertyList(){return proList;}public String getId() {return id;}public void setId(String id) {this.id = id;}public String getClassName() {return className;}public void setClassName(String className) {this.className = className;}}

BeanManager类文件

package com.huan.frame;public class BeanManager {public static Object createInstance(String name){try {return Class.forName(name).newInstance();} catch (InstantiationException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (IllegalAccessException e) {// TODO Auto-generated catch blocke.printStackTrace();} catch (ClassNotFoundException e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}}

ConfigFile类文件

package com.huan.frame;import java.util.*;public class ConfigFile {private List<Bean> beanList = new ArrayList<Bean>();public void addBean(Bean bean){beanList.add(bean);}public List<Bean> getBean(){return beanList;}}

ConfigManager类文件（84行一下这些类反射一直有个问题，希望大家能指点一下）

package com.huan.frame;import java.io.InputStream;import java.lang.reflect.*;import java.util.Iterator;import org.dom4j.*;import org.dom4j.io.SAXReader;public class ConfigManager {private ConfigFile config = new ConfigFile();public ConfigManager(String[] files){for (String file : files) {read(file);}}public void read(String file){try {if(file ==null || file.isEmpty()) throw new Exception("Spring：配置文件为空！");InputStream is = getClass().getResourceAsStream("/" + file);Document doc = new SAXReader().read(is);Element root = doc.getRootElement();Iterator<Element> beanIt = root.elementIterator("bean");Bean bean = null;Element beanEl = null,propertyEl = null;Iterator<Element> propertyIt = null;Property property = null;System.out.println("Spring：读取配置文件");while(beanIt.hasNext()){bean = new Bean();beanEl = beanIt.next();bean.setId(beanEl.attributeValue("id"));bean.setClassName(beanEl.attributeValue("class"));propertyIt = beanEl.elementIterator("property");while(propertyIt.hasNext()){property = new Property();propertyEl = propertyIt.next();property.setName(propertyEl.attributeValue("name"));property.setValue(propertyEl.attributeValue("value"));property.setRef(propertyEl.attributeValue("ref"));bean.aadProperty(property);}config.addBean(bean);}System.out.println("Spring：读取配置文件完毕");} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}}public Object getBean(String name){Object obj = null;try {if(name == null || name.isEmpty()) throw new Exception("Spring：bean名为空！");Iterator<Bean> beans = config.getBean().iterator();Bean bean = null;while(beans.hasNext()){bean = beans.next();if(name.equals(bean.getId())) break;else bean = null;}if(bean == null) throw new Exception("Spring：bean名未找到！");obj = BeanManager.createInstance(bean.getClassName());Iterator<Property> propertys = bean.getPropertyList().iterator();Property property = null;Class clazz = null;Method[] methods = null;Type[] types = null;String[] strs = null;Method sure = null;while(propertys.hasNext()){property = propertys.next();clazz = Class.forName(bean.getClassName());methods = clazz.getMethods();for (Method method : methods) {if(method.getName().equals(buildMethodName(property.getName()))){if(property.isValue()){types = method.getGenericParameterTypes();for (Type type : types) {strs = type.toString().split(" ");if(strs.length == 1){if(strs[0].equals("byte")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Byte"));sure.invoke(obj, Byte.parseByte(property.getValue()));}if(strs[0].equals("short")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Short"));sure.invoke(obj, Short.parseShort(property.getValue()));}if(strs[0].equals("int")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Integer"));sure.invoke(obj, Integer.parseInt(property.getValue()));}if(strs[0].equals("long")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Long"));sure.invoke(obj, Long.parseLong(property.getValue()));}if(strs[0].equals("float")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Float"));sure.invoke(obj, Float.parseFloat(property.getValue()));}if(strs[0].equals("double")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Double"));sure.invoke(obj, Double.parseDouble(property.getValue()));}if(strs[0].equals("char")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Character"));sure.invoke(obj, property.getValue().charAt(0));}if(strs[0].equals("boolean")){sure = clazz.getMethod(method.getName(), Class.forName("java.lang.Boolean"));sure.invoke(obj, Boolean.parseBoolean(property.getValue()));}}else{sure = clazz.getMethod(method.getName(), Class.forName(strs[1]));sure.invoke(obj, property.getValue());}}}else{Object var = getBean(property.getRef());sure = clazz.getMethod(method.getName(), var.getClass());sure.invoke(obj, var);}}}}return obj;} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}public String buildMethodName(String attName){try {if(attName == null || attName.isEmpty()) throw new Exception("Spring:创建方法的属性名为空！");return "set" + attName.substring(0,1).toUpperCase() + attName.substring(1);} catch (Exception e) {// TODO Auto-generated catch blocke.printStackTrace();}return null;}}

Property类文件

package com.huan.frame;public class Property {private String name;private String value;private String ref;public boolean isValue(){if(value.isEmpty())return false;return true;}public String getName() {return name;}public void setName(String name) {this.name = name;}public String getValue() {return value;}public void setValue(String value) {this.value = value;}public String getRef() {return ref;}public void setRef(String ref) {this.ref = ref;}}