模仿mybatis中的动态代理

SqlSession.getMapper的动态代理

//测试类
InputStream inputStream = Resources.getResourceAsStream("mybatis-config.xml");
SqlSessionFactory sqlSessionFactory = new SqlSessionFactoryBuilder().build(inputStream);
SqlSession sqlSession = sqlSessionFactory.openSession();
//关键
PersonDao persondao = Proxy.newProxyInstance(TestMybatis.class.getClassLoader,new Class[]{PersonDao.class},new Proxy(sqlSession，PersonDao.class));
Person person = personDao.selectByName("李小龙");
system.out.println(person);

//代理类
public class MyProxy implements InvocationHandler(){
    private SqlSession sqlSession;
    private Class daoClass;
    public MyProxy(SqlSession sqlSession,Class<PersonDao> personDaoClass){
        this.sqlSession = sqlSession;
        this.daoClass = personDaoClass;
    }
    @Override
    public Object invoke(Object proxy,Method method,Object[] args)throws Throwable{
        return sqlSession.selectOne(daoClass.getName()+"."+method.getName());
    }
}

在Mybatis 中是如何进行实现的呢

Mybatis 中有MapperProxy和MapperProxyFactory

MapperProxy的 作用：是相当于我们写的MyProxy（implement InvocationHandler）

invoke

​ SqlSession.insert()

​ sqlSession.update()

​ sqlSession.selectOne()

​ SqlSession.selectList()

MapperProxyFactory的作用：是相当于Proxy.newInstance()的方法