package com.etc.utils;

 import java.sql.Connection;

 import java.sql.DriverManager;

 import java.sql.PreparedStatement;

 import java.sql.ResultSet;

 import java.sql.SQLException;

 import javax.sql.rowset.CachedRowSet;

 import com.sun.rowset.CachedRowSetImpl;

 /**

  * 数据库访问的通用类

  *

  * @author Administrator

  *

  */

 public class DBUtil {

     private final static String URL = "jdbc:mysql://localhost/day07";

     private final static String USER = "root";

     private final static String PASSWORD = "123456";

     private final static String DRIVER = "com.mysql.jdbc.Driver";

     /**

      * 定义方法返回一个连接(Connection)对象

      *

      * @return 返回值就是一个连接对象

      */

     private static Connection getConnection() {

         Connection conn = null;

         try {

             Class.forName(DRIVER);

             conn = DriverManager.getConnection(URL, USER, PASSWORD);

         } catch (ClassNotFoundException e) {

             e.printStackTrace();

         } // 低版本的jdbc jar包

         catch (SQLException e) {

             e.printStackTrace();

         }

         return conn;

     }

     /**

      * 一个方法来做增加删除和修改

      *

      * @param sql   要执行的sql

      * @param param 执行的sql中包含的参数的实际值

      * @return int 表示的是受影响的行

      */

     public static int execUpdate(String sql, Object... param) {

         Connection conn = getConnection();

         PreparedStatement pstmt = null;

         int result = 0;

         try {

             pstmt = conn.prepareStatement(sql);

             for (int i = 0; i < param.length; i++) {

                 pstmt.setObject(i + 1, param[i]);

             }

             result = pstmt.executeUpdate();

         } catch (SQLException e) {

             e.printStackTrace();

         } finally {

             closeAll(null, pstmt, conn);

         }

         return result;

     }

     /**

      * 一个方法来做查询

      *

      * @param sql   要执行查询的sql语句

      * @param param 要执行sql对应的参数

      * @return CachedRowSet 缓存的结果集

      */

     public static CachedRowSet execQuery(String sql, Object... param) {

         Connection conn = getConnection();

         PreparedStatement pstmt = null;

         ResultSet rs = null;

         // 实例化CachedRowSetImpl

         CachedRowSetImpl crs = null;

         try {

             crs = new CachedRowSetImpl();

             pstmt = conn.prepareStatement(sql);

             // 可以吧param当成是一个数组

             System.out.println(param.length);

             for (int i = 0; i < param.length; i++) {

                 pstmt.setObject(i + 1, param[i]);

             }

             rs = pstmt.executeQuery();

             // 建立rs和crs关系，可以将rs的数据行缓存到crs中了

             crs.populate(rs);

         } catch (SQLException e) {

             e.printStackTrace();

         } finally {

             // 释放资源等 此处代码省略

             closeAll(rs, pstmt, conn);

         }

         return crs;

     }

     /**

      * 释放资源

      *

      * @param rs    结果集兑现

      * @param pstmt 预处理语句对象

      * @param conn  连接对象

      */

     private static void closeAll(ResultSet rs, PreparedStatement pstmt, Connection conn) {

         try {

             if (rs != null)

                 rs.close();

         } catch (SQLException e) {

             e.printStackTrace();

         }

         try {

             if (pstmt != null)

                 pstmt.close();

         } catch (SQLException e) {

             e.printStackTrace();

         }

         try {

             if (conn != null)

                 conn.close();

         } catch (SQLException e) {

             e.printStackTrace();

         }

     }

 }

 package com.etc.utils;

 import java.util.ArrayList;

 import java.util.List;

 public class Page<T> {

         // 总页数

         private int totalPageCount = 1;

         // 页面大小，即每页显示记录数

         private int pageSize = 10;

         // 记录总数

         private int totalCount = 0;

         // 当前页码

         private int currPageNo = 1;

         // 每页集合

         List<T> list = new ArrayList<>();

         public int getTotalPageCount() {

             return totalPageCount;

         }

         public void setTotalPageCount(int totalPageCount) {

             this.totalPageCount = totalPageCount;

         }

         public int getPageSize() {

             return pageSize;

         }

         public void setPageSize(int pageSize) {

             this.pageSize = pageSize;

         }

         public int getTotalCount() {

             return totalCount;

         }

         public void setTotalCount(int totalCount) {

             this.totalCount = totalCount;

         }

         public int getCurrPageNo() {

             return currPageNo;

         }

         public void setCurrPageNo(int currPageNo) {

             this.currPageNo = currPageNo;

         }

         public List<T> getList() {

             return list;

         }

         public void setList(List<T> list) {

             this.list = list;

         }

 }

 package com.etc.entity;

 public class User {

     private int uid=0;

     private String username;

     private String password;

     public User(int uid, String username, String password) {

         super();

         this.uid = uid;

         this.username = username;

         this.password = password;

     }

     public User() {

         super();

     }

     public int getUid() {

         return uid;

     }

     public void setUid(int uid) {

         this.uid = uid;

     }

     public String getUsername() {

         return username;

     }

     public void setUsername(String username) {

         this.username = username;

     }

     public String getPassword() {

         return password;

     }

     public void setPassword(String password) {

         this.password = password;

     }

 }