public class Main {     public static void main(String[] args) {          /******** 一般写法，Main类与Chinese类和American类之间的强耦合 ***********/          // Chinese和American，当类和方法修改时，此处的类和方法也需要修改          Chinese chinese = new Chinese();          chinese.sayHelloWorld("张三");          American american = new American();          american.sayHelloWorld("Jack");     }}/******************** 一般方法 ***************************/interface Human {     public void sayHelloWorld(String name);}class Chinese implements Human {     public void sayHelloWorld(String name) {          String helloWorld = "你好，" + name;          System.out.println(helloWorld);     }}class American implements Human {     public void sayHelloWorld(String name) {          String helloWorld = "Hello，" + name;          System.out.println(helloWorld);     }}

public class Main {     public static void main(String[] args) {          /******** 工厂方法， Main类与类Chinese和American不再耦合，仅仅和其接口Human耦合 ***********/          // 修改时还需要修改在Main类中修改这些字符串          // Chinese和American，当类和方法修改时，只有方法需要修改          HumanFactory humanFactory = new HumanFactory();          Human human1 = humanFactory.getHuman("chinese");          human1.sayHelloWorld("张三");          Human human2 = humanFactory.getHuman("american");          human2.sayHelloWorld("Jack");     }}/******************** 工厂方法 ***************************/interface Human {     public void sayHelloWorld(String name);}class HumanFactory {     public Human getHuman(String type) {          if ("chinese".equals(type)) {               return new Chinese();          } else {               return new American();          }     }}

public class Main {     public static void main(String[] args) {          /******************** IOC控制反转和依赖注入 ***************************/          // 利用容器，通过xml文件直接注入属性值，在Main类中只添加需要的          // Chinese和American，当类和方法修改时，代码完全不用修改，只需要修改xml文件即可，彻底实现了解耦          BeanFactory beanFactory = new BeanFactory();          beanFactory.init("/config.xml");          UserBean userBean = (UserBean) beanFactory.getBean("userBean");          System.out.println("userName=" + userBean.getUserName());          System.out.println("password=" + userBean.getPassword());     }}/******************** IOC控制反转和依赖注入 ***************************/// 下面是Spring的IOC实现：Bean工厂class BeanFactory {     private Map<String, Object> beanMap = new HashMap<String, Object>();     public void init(String fileName) {          try {               // 读取指定的配置文件               SAXReader reader = new SAXReader();               // System.out.println(xmlpath);               String realPathString = new File("").getCanonicalPath();               Document document = reader.read(new File(realPathString + "/src/com/devin/") + fileName);               Element root = document.getRootElement();               Element foo;               // 遍历bean               for (Iterator i = root.elementIterator("bean"); i.hasNext();) {                    foo = (Element) i.next();                    // 获取bean的属性id和class                    Attribute id = foo.attribute("id");                    Attribute cls = foo.attribute("class");                    // 利用Java反射机制，通过class的名称获取Class对象                    Class bean = Class.forName(cls.getText());                    // 获取对应class的信息                    java.beans.BeanInfo info = java.beans.Introspector.getBeanInfo(bean);                    // 获取其属性描述                    java.beans.PropertyDescriptor pd[] = info.getPropertyDescriptors();                    // 设置值的方法                    Method mSet = null;                    // 创建一个对象                    Object obj = bean.newInstance();                    // 遍历该bean的property属性                    for (Iterator ite = foo.elementIterator("property"); ite.hasNext();) {                         Element foo2 = (Element) ite.next();                         // 获取该property的name属性                         Attribute name = foo2.attribute("name");                         String value = null;                         // 获取该property的子元素value的值                         for (Iterator ite1 = foo2.elementIterator("value"); ite1.hasNext();) {                              Element node = (Element) ite1.next();                              value = node.getText();                              break;                         }                         for (int k = 0; k < pd.length; k++) {                              if (pd[k].getName().equalsIgnoreCase(name.getText())) {                                   mSet = pd[k].getWriteMethod();                                   mSet.invoke(obj, value);                              }                         }                    }                    // 将对象放入beanMap中，其中key为id值，value为对象                    beanMap.put(id.getText(), obj);               }          } catch (Exception e) {               System.out.println(e.toString());          }     }     // 通过bean的id获取bean的对象.     public Object getBean(String beanName) {          Object obj = beanMap.get(beanName);          return obj;     }}UserBean.javapublic class UserBean {     private String userName;     private String password;     public String getPassword() {          return password;     }     public String getUserName() {          return userName;     }     public void setUserName(String userName) {          this.userName = userName;     }     public void setPassword(String password) {          this.password = password;     }}config.xml<?xml version="1.0" encoding="UTF-8"?><beans>     <bean id="userBean" class="com.devin.UserBean">          <property name="userName">               <value>张三</value>          </property>          <property name="password">               <value>Jack</value>          </property>     </bean></beans>