1.实体类Customer.java

package loey.java1.bean;import java.sql.Date;/* * ORM编程思想  （object relational mapping） * 一个数据表对应一个java类 * 表中的一条记录对应java类的一个对象 * 表中的一个字段对应java类的一个属性 *  */public class Customer {
   		private int id;	private String name;	private String email;	private Date birth;	public Customer() {
   		super();	}	public Customer(int id, String name, String email, Date birth) {
   		super();		this.id = id;		this.name = name;		this.email = email;		this.birth = birth;	}	public int getId() {
   		return id;	}	public void setId(int id) {
   		this.id = id;	}	public String getName() {
   		return name;	}	public void setName(String name) {
   		this.name = name;	}	public String getEmail() {
   		return email;	}	public void setEmail(String email) {
   		this.email = email;	}	public Date getBirth() {
   		return birth;	}	public void setBirth(Date birth) {
   		this.birth = birth;	}	@Override	public String toString() {
   		return "Customer [id=" + id + ", name=" + name + ", email=" + email + ", birth=" + birth + "]";	}			}

2.BaseDAO.java

/* * DAO: data(base) access object * 封装了针对于数据表的通用的操作 */public abstract class BaseDAO
   
     {
   		private Class
    
      clazz = null;	//	public BaseDAO(){
   //		//	}		{
   			//获取当前BaseDAO的子类继承的父类中的泛型		Type genericSuperclass = this.getClass().getGenericSuperclass();		ParameterizedType paramType = (ParameterizedType) genericSuperclass;				Type[] typeArguments = paramType.getActualTypeArguments();//获取了父类的泛型参数		clazz = (Class
     
      ) typeArguments[0];//泛型的第一个参数			}			// 通用的增删改操作---version 2.0 （考虑上事务	public int update(Connection conn, String sql, Object... args) {
   // sql中占位符的个数与可变形参的长度相同！		PreparedStatement ps = null;		try {
   			// 1.预编译sql语句，返回PreparedStatement的实例			ps = conn.prepareStatement(sql);			// 2.填充占位符			for (int i = 0; i < args.length; i++) {
   				ps.setObject(i + 1, args[i]);// 小心参数声明错误！！			}			// 3.执行			return ps.executeUpdate();		} catch (Exception e) {
   			e.printStackTrace();		} finally {
   			// 4.资源的关闭			JDBCUtils.closeResource(null, ps);		}		return 0;	}	// 通用的查询操作，用于返回数据表中的一条记录（version 2.0：考虑上事务	public T getInstance(Connection conn, String sql, Object... args) {
   		PreparedStatement ps = null;		ResultSet rs = null;		try {
   			ps = conn.prepareStatement(sql);			for (int i = 0; i < args.length; i++) {
   				ps.setObject(i + 1, args[i]);			}			rs = ps.executeQuery();			// 获取结果集的元数据 :ResultSetMetaData			ResultSetMetaData rsmd = rs.getMetaData();			// 通过ResultSetMetaData获取结果集中的列数			int columnCount = rsmd.getColumnCount();			if (rs.next()) {
   				T t = clazz.newInstance();				// 处理结果集一行数据中的每一个列				for (int i = 0; i < columnCount; i++) {
   					// 获取列值					Object columValue = rs.getObject(i + 1);					// 获取每个列的列名					// String columnName = rsmd.getColumnName(i + 1);					String columnLabel = rsmd.getColumnLabel(i + 1);					// 给t对象指定的columnName属性，赋值为columValue：通过反射					Field field = clazz.getDeclaredField(columnLabel);					field.setAccessible(true);					field.set(t, columValue);				}				return t;			}		} catch (Exception e) {
   			e.printStackTrace();		} finally {
   			JDBCUtils.closeResource(null, ps, rs);		}		return null;	}	// 通用的查询操作，用于返回数据表中的多条记录构成的集合（version 2.0：考虑上事务	public List
      
        getForList(Connection conn, String sql, Object... args) {
   		PreparedStatement ps = null;		ResultSet rs = null;		try {
   			ps = conn.prepareStatement(sql);			for (int i = 0; i < args.length; i++) {
   				ps.setObject(i + 1, args[i]);			}			rs = ps.executeQuery();			// 获取结果集的元数据 :ResultSetMetaData			ResultSetMetaData rsmd = rs.getMetaData();			// 通过ResultSetMetaData获取结果集中的列数			int columnCount = rsmd.getColumnCount();			// 创建集合对象			ArrayList
       
         list = new ArrayList
        
         (); while (rs.next()) { T t = clazz.newInstance(); // 处理结果集一行数据中的每一个列:给t对象指定的属性赋值 for (int i = 0; i < columnCount; i++) { // 获取列值 Object columValue = rs.getObject(i + 1); // 获取每个列的列名 // String columnName = rsmd.getColumnName(i + 1); String columnLabel = rsmd.getColumnLabel(i + 1); // 给t对象指定的columnName属性，赋值为columValue：通过反射 Field field = clazz.getDeclaredField(columnLabel); field.setAccessible(true); field.set(t, columValue); } list.add(t); } return list; } catch (Exception e) { e.printStackTrace(); } finally { JDBCUtils.closeResource(null, ps, rs); } return null; } //用于查询特殊值的通用的方法 public 
         
           E getValue(Connection conn,String sql,Object...args){ PreparedStatement ps = null; ResultSet rs = null; try { ps = conn.prepareStatement(sql); for(int i = 0;i < args.length;i++){ ps.setObject(i + 1, args[i]); } rs = ps.executeQuery(); if(rs.next()){ return (E) rs.getObject(1); } } catch (SQLException e) { e.printStackTrace(); }finally{ JDBCUtils.closeResource(null, ps, rs); } return null; } }

3.CustomerDAO.java

/* * 此接口用于规范针对于customers表的常用操作 */public interface CustomerDAO {
   	/**	 * 	 * @Description 将cust对象添加到数据库中	 * @author shkstart	 * @date 上午11:00:27	 * @param conn	 * @param cust	 */	void insert(Connection conn,Customer cust);	/**	 * 	 * @Description 针对指定的id，删除表中的一条记录	 * @author shkstart	 * @date 上午11:01:07	 * @param conn	 * @param id	 */	void deleteById(Connection conn,int id);	/**	 * 	 * @Description 针对内存中的cust对象，去修改数据表中指定的记录	 * @author shkstart	 * @date 上午11:02:14	 * @param conn	 * @param cust	 */	void update(Connection conn,Customer cust);	/**	 * 	 * @Description 针对指定的id查询得到对应的Customer对象	 * @author shkstart	 * @date 上午11:02:59	 * @param conn	 * @param id	 */	Customer getCustomerById(Connection conn,int id);	/**	 * 	 * @Description 查询表中的所记录构成的集合	 * @author shkstart	 * @date 上午11:03:50	 * @param conn	 * @return	 */	List
   
     getAll(Connection conn);	/**	 * 	 * @Description 返回数据表中的数据的条目数	 * @author shkstart	 * @date 上午11:04:44	 * @param conn	 * @return	 */	Long getCount(Connection conn);		/**	 * 	 * @Description 返回数据表中最大的生日	 * @author shkstart	 * @date 上午11:05:33	 * @param conn	 * @return	 */	Date getMaxBirth(Connection conn);	}

4.CustomerDAOImpl.java

public class CustomerDAOImpl extends BaseDAO
   
     implements CustomerDAO{
   		@Override	public void insert(Connection conn, Customer cust) {
   		String sql = "insert into customers(name,email,birth)values(?,?,?)";		update(conn, sql,cust.getName(),cust.getEmail(),cust.getBirth());	}	@Override	public void deleteById(Connection conn, int id) {
   		String sql = "delete from customers where id = ?";		update(conn, sql, id);	}	@Override	public void update(Connection conn, Customer cust) {
   		String sql = "update customers set name = ?,email = ?,birth = ? where id = ?";		update(conn, sql,cust.getName(),cust.getEmail(),cust.getBirth(),cust.getId());	}	@Override	public Customer getCustomerById(Connection conn, int id) {
   		String sql = "select id,name,email,birth from customers where id = ?";		Customer customer = getInstance(conn, sql,id);		return customer;	}	@Override	public List
    
      getAll(Connection conn) {
   		String sql = "select id,name,email,birth from customers";		List
     
       list = getForList(conn, sql);		return list;	}	@Override	public Long getCount(Connection conn) {
   		String sql = "select count(*) from customers";		return getValue(conn, sql);	}	@Override	public Date getMaxBirth(Connection conn) {
   		String sql = "select max(birth) from customers";		return getValue(conn, sql);	}}

5.测试

package loey.java1.dao.junit;import loey.DBCUtil.DBCUtil;import loey.java1.bean.Customer;import loey.java1.dao.CustomerDAOImpl;import org.junit.Test;import java.net.DatagramSocket;import java.sql.Connection;import java.sql.Date;import java.text.DateFormat;import java.text.SimpleDateFormat;import java.time.format.DateTimeFormatter;import java.time.temporal.TemporalAccessor;import java.util.List;public class CustomerDAOImplTest {
       private CustomerDAOImpl dao = new CustomerDAOImpl();    @Test    public void testInsert() {
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");            java.util.Date date = sdf.parse("1992-11-27");            Customer cust = new Customer(1, "朴灿烈", "pcy@163.com", new Date(date.getTime()));            dao.insert(conn, cust);            System.out.println("添加成功！");        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testDeleteById(){
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            int id = 24;            dao.deleteById(conn,id);            System.out.println("删除成功");        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testUpade(){
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            SimpleDateFormat sdf = new SimpleDateFormat("yyyy-MM-dd");            java.util.Date date = sdf.parse("1992-04-06");            Customer cust = new Customer(23,"边伯贤","bbx@163.com",new Date(date.getTime()));            dao.update(conn,cust);            System.out.println("修改成功");        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testGetCustomerById(){
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            int id = 6;            Customer customer = dao.getCustomerById(conn, id);            System.out.println(customer);        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testGetAll(){
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            int id = 6;            List
   
     customers = dao.getAll(conn, id);          customers.forEach(System.out::println);        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testGetCount(){
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            Long count = dao.getCount(conn);            System.out.println("该表共有" + count + "人");        } catch (Exception e) {
               e.printStackTrace();        } finally {
               DBCUtil.close(conn,null,null);        }    }    @Test    public void testGetMaxBirth() {
           Connection conn = null;        try {
               conn = DBCUtil.getConnection();            Date maxBirth = dao.getMaxBirth(conn);            System.out.println("最大的生日为：" + maxBirth);        } catch (Exception e) {
               e.printStackTrace();        }finally{
               DBCUtil.close(conn, null,null);        }    }}