动态代理学习小案例

 1 package edu.nf.utils;
 2 
 3 import edu.nf.dao.UserDao;
 4 import edu.nf.dao.UserInvocationhandler;
 5 import org.apache.ibatis.session.SqlSession;
 6 
 7 import java.lang.reflect.InvocationHandler;
 8 import java.lang.reflect.Proxy;
 9 
10 /**
11  * 代理工具
12  * @Author LQY
13  * @Date 2018/10/15
14  */
15 public class ProxyUtil {
16     /**
17      * 在使用mybatis前提下，获取操作数据库dao的实现类的代理对象
18      * @param clazz dao接口的class对象
19      * @return
20      */
21     public static Object getProxy(Class<?> clazz){
22         SqlSession sqlSession = MyBatisUtil.getSqlSession();
23         Object dao = sqlSession.getMapper(clazz);
24         try {
25             InvocationHandler handler = new DaoInvocationhandler(dao);
26            return Proxy.newProxyInstance(clazz.getClassLoader(), dao.getClass().getInterfaces(), handler);
27         } catch (Exception e) {
28             e.printStackTrace();
29         }
30         return null;
31     }
32 }

package edu.nf.dao;

import edu.nf.utils.MyBatisUtil;
import org.apache.ibatis.session.SqlSession;

import java.lang.reflect.InvocationHandler;
import java.lang.reflect.Method;

/**
 * 回调处理器
 * @Author LQY
 * @Date 2018/10/15
 */
public class DaoInvocationhandler implements InvocationHandler{
   private Object target ;
   public UserInvocationhandler(Object target){
       this.target = target;
   }
    @Override
    public Object invoke(Object proxy, Method method, Object[] args) throws Throwable {
        Object obj = null;
        SqlSession sqlSession = MyBatisUtil.getSqlSession();
        try {
            obj = method.invoke(target,args);
            //提交事务
            sqlSession.commit();
        } catch (Exception e) {
            e.printStackTrace();
            //回滚事务
            sqlSession.rollback();
        }finally {
            //释放SqlSession
            sqlSession.close();
        }
        return obj;
    }
}

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