Java動(dòng)態(tài)代理實(shí)現(xiàn)_動(dòng)力節(jié)點(diǎn)Java學(xué)院整理

import java.lang.reflect.Proxy; 
import java.lang.reflect.InvocationHandler; 
import java.lang.reflect.InvocationTargetException; 
import java.lang.reflect.Method; 
import java.util.Calendar; 
import java.util.GregorianCalendar; 
 
//抽象UserDAO：抽象主題角色 
interface AbstractUserDAO { 
  public Boolean findUserById(String userId); 
} 
 
//抽象DocumentDAO：抽象主題角色 
interface AbstractDocumentDAO { 
  public Boolean deleteDocumentById(String documentId); 
} 
 
//具體UserDAO類：真實(shí)主題角色 
class UserDAO implements AbstractUserDAO { 
  public Boolean findUserById(String userId) { 
    if (userId.equalsIgnoreCase("張無(wú)忌")) { 
      System.out.println("查詢ID為" + userId + "的用戶信息成功！"); 
      return true; 
    } 
    else { 
      System.out.println("查詢ID為" + userId + "的用戶信息失??！"); 
      return false; 
    } 
  } 
} 
 
//具體DocumentDAO類：真實(shí)主題角色 
class DocumentDAO implements AbstractDocumentDAO { 
  public Boolean deleteDocumentById(String documentId) { 
    if (documentId.equalsIgnoreCase("D001")) { 
      System.out.println("刪除ID為" + documentId + "的文檔信息成功！"); 
      return true; 
    } 
    else { 
      System.out.println("刪除ID為" + documentId + "的文檔信息失敗！"); 
      return false; 
    } 
  } 
} 
 
//自定義請(qǐng)求處理程序類 
class DAOLogHandler implements InvocationHandler { 
  private Calendar calendar; 
  private Object object; 
   
  public DAOLogHandler() {   
  } 
   
  //自定義有參構(gòu)造函數(shù)，用于注入一個(gè)需要提供代理的真實(shí)主題對(duì)象 
  public DAOLogHandler(Object object) { 
    this.object = object; 
  } 
   
  //實(shí)現(xiàn)invoke()方法，調(diào)用在真實(shí)主題類中定義的方法 
  public Object invoke(Object proxy, Method method, Object[] args) throws Throwable { 
    beforeInvoke(); 
    Object result = method.invoke(object, args); //轉(zhuǎn)發(fā)調(diào)用 
    afterInvoke(); 
    return null; 
  } 
 
  //記錄方法調(diào)用時(shí)間 
  public void beforeInvoke(){ 
    calendar = new GregorianCalendar(); 
    int hour = calendar.get(Calendar.HOUR_OF_DAY); 
    int minute = calendar.get(Calendar.MINUTE); 
    int second = calendar.get(Calendar.SECOND); 
    String time = hour + ":" + minute + ":" + second; 
    System.out.println("調(diào)用時(shí)間：" + time); 
  } 
 
  public void afterInvoke(){ 
    System.out.println("方法調(diào)用結(jié)束！" ); 
  } 
} 

class Client { 
  public static void main(String args[]) { 
    InvocationHandler handler = null; 
     
    AbstractUserDAO userDAO = new UserDAO(); 
    handler = new DAOLogHandler(userDAO); 
    AbstractUserDAO proxy = null; 
    //動(dòng)態(tài)創(chuàng)建代理對(duì)象，用于代理一個(gè)AbstractUserDAO類型的真實(shí)主題對(duì)象 
    proxy = (AbstractUserDAO)Proxy.newProxyInstance(AbstractUserDAO. class.getClassLoader(), new Class[]{AbstractUserDAO.class}, handler); 
    proxy.findUserById("張無(wú)忌"); //調(diào)用代理對(duì)象的業(yè)務(wù)方法 
   
    System.out.println("------------------------------"); 
   
    AbstractDocumentDAO docDAO = new DocumentDAO(); 
    handler = new DAOLogHandler(docDAO); 
    AbstractDocumentDAO proxy_new = null; 
//動(dòng)態(tài)創(chuàng)建代理對(duì)象，用于代理一個(gè)AbstractDocumentDAO類型的真實(shí)主題對(duì)象 
    proxy_new = (AbstractDocumentDAO)Proxy.newProxyInstance(Abstract DocumentDAO.class.getClassLoader(), new Class[]{AbstractDocumentDAO.class}, handler); 
    proxy_new.deleteDocumentById("D002"); //調(diào)用代理對(duì)象的業(yè)務(wù)方法 
  }  
} 

調(diào)用時(shí)間：13:47:14
查詢ID為張無(wú)忌的用戶信息成功！
方法調(diào)用結(jié)束！
------------------------------
調(diào)用時(shí)間：13:47:14
刪除ID為D002的文檔信息失敗！
方法調(diào)用結(jié)束！