类似mybatis的功能

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今天老师讲了mybatis的入门,作为入门基础没有将太多的mybatis的用法.而是通过一个实例,讲解了mybatis所实现的功能.这个实例就是定义了一个接口,用来执行所有的sql查询.在实现这个接口的过程中,用到了包括反射机制,generic等很多知识.

public interface SqlSession {// <T> T selectOne(String sql, Class<T> clazz, Object... params);<T> T selectOne(String sql, Class<T> clazz, Map<String, Object> params) throws SQLException;/* * 1, (sql, params) => statement *  * 2, (clazz) => typehandler * 3, typehandler.handler(rs) * 4, return t */<E> List<E> selectList(String sql, Class<E> clazz, Object... params) throws SQLException;int update(String sql, Object... params) throws SQLException;}

public <T> T selectOne(String sqlId, Class<T> clazz, Map<String, Object> params) {// 1. Open connection <= Connection pool// 2. Prepare statement <= PreparedStatement (maybe cached to reuse)// 3. Execute SQL with parameter<= Database// 4. Get appropriate type handler  <= TypeHandler// 5. Handle result set=> handle(result set, class type) => Object/List// 6. Release connection etc.// 7. Return result of step 5return null;}

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