java IoC，javaioc

java IoC，javaioc

     IoC，控制反轉，是spring的核心，通俗點講就是我們不必再自己去用new建立對象了，通過l配置將類注入到IoC容器中，在啟動時，IoC容器去幫我們建立對象，並管理其依賴關係，這種實現方式叫做DI，依賴注入。為什麼我們要用IoC去幫我們管理對象呢，因為通常一個商務邏輯都是由多個對象合作完成工作的，如果自己管理的話比較，就要在一個方法中調用多個對象，不好管理，重用性低。

     //使用原廠模式加設定檔的方式模範了一個簡易IoC的工作原理 //1.BeanFactory.java  bean工廠，建立對象 //2.PropertiesReader.java 讀取設定檔 //3.普通bean類 //4.測試類別  

 1 package myIoC; 2 /** 3  * 1.讀取設定檔介面，有兩個實作類別，一個用類載入路徑讀取設定檔，第二個用檔案路徑讀取設定檔 4  * 2.提供BeanFactory 方法 5  * @author LH-PC 6  * 7  */ 8 public interface ApplicationContext { 9     10     /**11      * beanFactory 方法12      * @param name13      * @return14      */15     Object getBean(String name);16     Object getBean(String name, String className);17     18 }

 1 package myIoC; 2  3 import java.util.Date; 4 import java.util.Map; 5  6 /** 7  * ApplicationContext實作類別之一，類載入讀取設定檔 8  * @author LH-PC 9  *10  */11 public class ClassPathXmlApplicationContext implements ApplicationContext{12 13     private String propertiesName;14     15     /**16      * 構造方法用於載入設定檔17      * @param xml18      */19     public ClassPathXmlApplicationContext(String propertiesName){20         //初始化屬性21         this.propertiesName = propertiesName;22     }23     24     /**25      * 通過類載入方式的Factory 方法26      */27     public Object getBean(String name) {28         //讀取設定檔29         PropertiesReader propertiesReader = new PropertiesReader(propertiesName);30         Object object = null;31         //建立對象32         Map<String, String> map = propertiesReader.getProperties();33         try {34             System.err.println(new Date() +": " + "BeanFactory開始生產對象...");35             object =  Class.forName(map.get(name)).newInstance();36             System.err.println(new Date() +": " + "生產對象完畢");37         } catch (InstantiationException e) {38             System.err.println(new Date() +": " + "建立對象異常");39             e.printStackTrace();40         } catch (IllegalAccessException e) {41             System.err.println(new Date() +": " + "IllegalAccessException異常");42             e.printStackTrace();43         } catch (ClassNotFoundException e) {44             System.err.println(new Date() +": " + "類載入異常");45             e.printStackTrace();46         }47         48         return object;49     }50 51     public Object getBean(String name, String className) {52         // TODO Auto-generated method stub53         return null;54     }55 56 }

 1 package myIoC; 2  3 import java.io.IOException; 4 import java.io.InputStream; 5 import java.util.Date; 6 import java.util.Enumeration; 7 import java.util.HashMap; 8 import java.util.Map; 9 import java.util.Properties;10 11 //讀取properties檔案類12 public class PropertiesReader {13     14     private Properties pro = null;15     private InputStream in = null;16     private String propertiesName = null;17     18     public PropertiesReader(String propertiesName){19         this.propertiesName = propertiesName;20     }21 22     @SuppressWarnings("rawtypes")23     public  Map<String,String> getProperties(){24         Map<String, String> map = new HashMap<String, String>();25         pro = new Properties();  //建立properties對象26         try {27             System.err.println(new Date() +": " + "開始讀取" + propertiesName + "...");28             in = PropertiesReader.class.getClassLoader().getResourceAsStream(propertiesName); //通過反射機制讀取設定檔29             if(in == null){30                 System.err.println(new Date() +": " + "讀取流為空白");31             }else{32                 //開始負載檔案內容33                 pro.load(in);34                 System.err.println(new Date() +": " + propertiesName + "讀取成功");35             }36             Enumeration en = pro.propertyNames();        //迭代器遍曆pro37             while(en.hasMoreElements()){38                 String key = (String) en.nextElement();  //遍曆key39                 String value = pro.getProperty(key);     //根據key取出value，放進map40                 map.put(key,value);41             }42         } catch (IOException e) {43             System.err.println(new Date() +": " + "io異常");44             e.printStackTrace();45         }46         finally{47             if(in != null){48                 try {49                     in.close();//關閉讀取流50                     System.err.println(new Date() +": " + "讀取流關閉成功");51                 } catch (IOException e) {52                     System.err.println(new Date() +": " + "讀取流關閉失敗");53                     e.printStackTrace();54                 }  55             }56         }57         return map;58     }59     60     public static void main(String[] args) {61         PropertiesReader propertiesReader = new PropertiesReader("myIoc/applicationContext.properties");62         Map<String, String> map = propertiesReader.getProperties();63         System.out.println("ok");64     }65 66 }

student=myIoC.Studentbean2=test.BeansImpl2bean3=test.BeansImpl3

 1 package myIoC; 2  3 /** 4  * MyIoC測試類別 5  * @author LH-PC 6  */ 7 public class IoCTest { 8     public static void main(String[] args) { 9         ApplicationContext applicationContext = new ClassPathXmlApplicationContext("myIoc/applicationContext.properties");10         Student student = (Student) applicationContext.getBean("student");11         student.setSid("15301");12         student.setSname("海");13         System.out.println(student.getSid());14         System.out.println(student.getSname());15 16     }17 18 }19 20 /**21  * 測試實體類22  * @author LH-PC23  *24  */25 class Student {26     private String sname;27     private String sid;28 29     public String getSname() {30         return sname;31     }32 33     public void setSname(String sname) {34         this.sname = sname;35     }36 37     public String getSid() {38         return sid;39     }40 41     public void setSid(String sid) {42         this.sid = sid;43     }44 45 }