结构：

DAO2_7< T >（接口）—>DAOTestImpl< T >（实现类）—>CustomerDAO（继承的子类）—>CustomerDAOTest（继承的测试类）

代码：

• 接口：

package JDBC;import java.sql.Connection;import java.sql.SQLException;import java.util.List;/** * 访问数据的接口 *其中定义了访问数据表的各种方法 *@param T：DAO处理的实体类的类型 *版本：2.0 * */public interface DAO2_7
    
      {    /**     * 1.功能：insert、update、delete     * @param conn：链接数据库     * @param sql：SQL语句     * @param objects：占位符的可变参数     * @throws SQLException      */    void update(Connection conn, String sql, Object ... objects ) throws SQLException;    /**     * 2.功能：返回一个T类型对象     * @param conn     * @param sql     * @param objects     * @return     * @throws SQLException      */    T get(Connection conn, String sql, Object ...objects) throws SQLException;    /**     * 3.功能：返回一个T类型的对象的集合     * @param conn     * @param sql     * @param objects     * @return     * @throws SQLException      */    List
     
       getForList(Connection conn, String sql, Object ...objects) throws SQLException;    /**     * 4.返回具体的一个值，例如：总人数、平均数，某个人的名字。     * @param conn     * @param sql     * @param objects     * @return     * @throws SQLException      */    
      
        E getForValue(Connection conn, String sql, Object ...objects) throws SQLException;    /**     * 5.批量处理的方法     * @param conn     * @param sql     * @param objects：填充占位符的Object[]类型的可变参数     * @throws SQLException      */    void batch(Connection conn, String sql, Object[] ...objects) throws SQLException;}
      
     
    

• 实现类

package JDBC;import java.sql.Connection;import java.sql.SQLException;import java.util.List;import org.apache.commons.dbutils.QueryRunner;import org.apache.commons.dbutils.handlers.BeanHandler;import org.apache.commons.dbutils.handlers.BeanListHandler;import org.apache.commons.dbutils.handlers.ScalarHandler;import 反射机制.ReflectionUtils;public class DAOTestImpl
    
      implements DAO2_7
     
       {    private QueryRunner queryRunner = null;    private Class 
      
        type;    //构造器    public DAOTestImpl(){        queryRunner = new QueryRunner();        type = ReflectionUtils.getSuperGenericType(getClass());    }    //更新数据    @Override    public void update(Connection conn, String sql, Object... objects) throws SQLException {        queryRunner.update(conn, sql, objects);    }    //查询数据    @Override    public T get(Connection conn, String sql, Object... objects) throws SQLException {        return queryRunner.query(conn, sql, new BeanHandler<>(type), objects);    }    //获取多条记录    @Override    public List
       
         getForList(Connection conn, String sql, Object... objects) throws SQLException {        return queryRunner.query(conn, sql, new BeanListHandler<>(type), objects);    }    //获取某一列值，或计算总数    @Override    public 
        
          E getForValue(Connection conn, String sql, Object... objects) throws SQLException {        return (E)queryRunner.query(conn, sql, new ScalarHandler(), objects);    }    //批量操作    @Override    public void batch(Connection conn, String sql, Object[]... objects) throws SQLException {        queryRunner.batch(conn, sql, objects);    }}
        
       
      
     
    

• 继承的子类

package JDBC;import JDBCTest.Customers;public class CustomerDAO extends DAOTestImpl
    
      {
    }
    

• 继承子类的测试类

package JDBC;import java.sql.Connection;import java.sql.Date;import java.util.List;import org.junit.Test;import JDBCTest.Customers;import JDBCTest.TestTools;public class CustomerDAOTest extends CustomerDAO {
        Connection conn = null;    CustomerDAO customerDao = new CustomerDAO();    //构造器    public CustomerDAOTest() throws Exception{        conn = TestTools.getConnection();    }    @Test    public void testUpdate() {        try {            String sql = "INSERT INTO customers(id,name,age,birth,address) VALUES(?, ?, ?, ?, ?)";            customerDao.update(conn, sql, 1, "张力", "32", new Date(new java.util.Date().getTime()), "上海市" );            System.out.println("OK");        } catch (Exception e) {            e.printStackTrace();        }finally{            TestTools.release(null, conn);        }    }    @Test    public void testGet() {        try {            String sql = "select id, name, age, birth from customers where id = ?";            Customers customer = customerDao.get(conn, sql, 15);            System.out.println(customer);        } catch (Exception e) {            e.printStackTrace();        }finally{            TestTools.release(null, conn);        }    }    @Test    public void testGetForList() {        try {                String sql = "select id, name, age, birth from customers where id > ?";                List
    
      customers = customerDao.getForList(conn, sql, 15);                System.out.println(customers);            } catch (Exception e) {                e.printStackTrace();            }finally{                TestTools.release(null, conn);            }    }    @Test    public void testGetForValue() {        try {            String sql = "select count(id) from customers";            Object result = customerDao.getForValue(conn, sql, null);            System.out.println(result);        } catch (Exception e) {            e.printStackTrace();        }finally{            TestTools.release(null, conn);        }    }    @Test    public void testBatch() {        try {            String sql = "INSERT INTO customers(name, age, birth, address) VALUES(?, ?, ?, ?)";            Object objects[][] = new Object[1000][4];            for(int i = 0; i < 1000; i++){                objects[i][0] = "name_"+i;                objects[i][1] = "20";                objects[i][2] = (new Date(new java.util.Date().getTime()));                objects[i][3] = "河南省";            }            customerDao.batch(conn, sql, objects);            System.out.println("OK");        } catch (Exception e) {            e.printStackTrace();        }finally{            TestTools.release(null, conn);        }    }}