JDBC增刪查改3

步驟1、編寫xml配置文件

<?xml version="1.0" encoding="utf-8"  ?>
<!--
數據庫相關信息: 1、驅動；2、url；3、user；4、password
-->
<config>
<db-info>
<driver-name>com.mysql.jdbc.Driver</driver-name>
<url>jdbc:mysql://localhost:3306/test?autoReconnect=true&useUnicode=true&characterEncoding=UTF-8</url>
<user-name>root</user-name>
<password>root</password>
</db-info>
</config> 

步驟2、編寫實體類JdbcConfig

package net.etwo.model;

public class JdbcConfig {

/**
* 數據庫相關信息
* 1、驅動；2、url；3、user；4、password
*/
private String driverName;

private String url;

private String user;

private String password;

public String getDriverName() {
return driverName;
}

public void setDriverName(String driverName) {
this.driverName = driverName;
}

public String getUrl() {
return url;
}

public void setUrl(String url) {
this.url = url;
}

public String getUser() {
return user;
}

public void setUser(String user) {
this.user = user;
}

public String getPassword() {
return password;
}

public void setPassword(String password) {
this.password = password;
}

@Override
public String toString() {
// TODO Auto-generated method stub
return "driverName:" + this.driverName + "\nurl:" + this.url + "\nuser:" + this.user + "\npassword:" + this.password;
}

}

3、創建DbUtil類，封裝獲取連接、關閉連接等操作。

 
public class DbUtil {
  
 
 /**
  * 取得Connection
  * @return
  */
 public static Connection getConnection() {
 
  Connection conn = null;
  try {
   JdbcConfig jdbcConfig = XmlConfigReader.getInstance().getJdbcConfig();
   Class.forName(jdbcConfig.getDriverName());
   conn = DriverManager.getConnection(jdbcConfig.getUrl(), jdbcConfig.getUserName(), jdbcConfig.getPassword());
  } catch (ClassNotFoundException e) {
   e.printStackTrace();
  } catch (SQLException e) {
   e.printStackTrace();
  }
  return conn;
 }
  
 public static void close(Connection conn) {
  if (conn != null) {
   try {
    conn.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
 }
  
 public static void close(PreparedStatement pstmt) {
  if (pstmt != null) {
   try {
    pstmt.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
 }
  
 public static void close(ResultSet rs ) {
  if (rs != null) {
   try {
    rs.close();
   } catch (SQLException e) {
    e.printStackTrace();
   }
  }
 }
 //測試連接是否成功
 public static void main(String[] args) {
  System.out.println(DbUtil.getConnection());
 }
}
  

4、採用單例模式建立Manager類進行JDBC操作。

 
public class UserManager { 
 
 private static UserManager instance = new UserManager();
  
 private UserManager() {}
  
 public static UserManager getInstance() {
  return instance;
 }
  
 /**
  * 添加用戶
  * @param user
  */
 public void addUser(User user) {
  String sql = "insert into t_user (user_id, user_name, password, contact_tel, email, create_date) " +
    " values (?, ?, ?, ?, ?, ?)";
  Connection conn = null;
  PreparedStatement pstmt = null;
  try {
   conn = DbUtil.getConnection();
   pstmt = conn.prepareStatement(sql);
   pstmt.setString(1, user.getUserId());
   pstmt.setString(2, user.getUserName());
   pstmt.setString(3, user.getPassword());
   pstmt.setString(4, user.getContactTel());
   pstmt.setString(5, user.getEmail());
   //pstmt.setTimestamp(6, new Timestamp(System.currentTimeMillis()));
   pstmt.setTimestamp(6, new Timestamp(new Date().getTime()));
   pstmt.executeUpdate();
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   DbUtil.close(pstmt);
   DbUtil.close(conn);
  }
 }
  
 /**
  * 根據用戶代碼查詢
  * @param userId
  * @return 如果存在返回User對象，否則返回null
  */
 public User findUserById(String userId) {
  System.out.println("UserManager.findUserById() -- userId=" + userId);
  String sql = "select user_id, user_name, password, contact_tel, email, create_date from t_user where user_id=?";
  Connection conn = null;
  PreparedStatement pstmt = null;
  ResultSet rs = null;
  User user = null;
  try {
   conn = DbUtil.getConnection();
   pstmt = conn.prepareStatement(sql);
   pstmt.setString(1, userId);
   rs = pstmt.executeQuery();
   if (rs.next()) {
    user = new User();
    user.setUserId(rs.getString("user_id"));
    user.setUserName(rs.getString("user_name"));
    user.setPassword(rs.getString("password"));
    user.setContactTel(rs.getString("contact_tel"));
    user.setEmail(rs.getString("email"));
    user.setCreateDate(rs.getTimestamp("create_date"));
   }
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   DbUtil.close(rs);
   DbUtil.close(pstmt);
   DbUtil.close(conn);
  }
  return user;
 }
  
 /**
  * 分頁查詢
  * @param pageNo 第幾頁
  * @param pageSize 每頁多少條數據
  * @return pageModel
  */
 public PageModel<User> findUserList(int pageNo, int pageSize) {
  StringBuffer sbSql = new StringBuffer(); 
  sbSql.append("select user_id, user_name, password, contact_tel, email, create_date ")
   .append("from ")
   .append("( ")
   .append("select rownum rn, user_id, user_name, password, contact_tel, email, create_date ")
   .append("from ")
   .append("( ")
   .append("select user_id, user_name, password, contact_tel, email, create_date from t_user where user_id <> 'root' order by user_id ")
   .append(")  where rownum <= ? ")
   .append(")  where rn > ? ");
  Connection conn = null;
  PreparedStatement pstmt = null;
  ResultSet rs = null;
  PageModel<User> pageModel = null;
  try {
   conn = DbUtil.getConnection();
   pstmt = conn.prepareStatement(sbSql.toString());
   pstmt.setInt(1, pageNo * pageSize);
   pstmt.setInt(2, (pageNo - 1) * pageSize);
   rs = pstmt.executeQuery();
   List<User> userList = new ArrayList<User>();
   while (rs.next()) {
    User user = new User();
    user.setUserId(rs.getString("user_id"));
    user.setUserName(rs.getString("user_name"));
    user.setPassword(rs.getString("password"));
    user.setContactTel(rs.getString("contact_tel"));
    user.setEmail(rs.getString("email"));
    user.setCreateDate(rs.getTimestamp("create_date"));
    userList.add(user);
   }
   pageModel = new PageModel<User>();
   pageModel.setList(userList);
   pageModel.setTotalRecords(getTotalRecords(conn));
   pageModel.setPageSize(pageSize);
   pageModel.setPageNo(pageNo);
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   DbUtil.close(rs);
   DbUtil.close(pstmt);
   DbUtil.close(conn);
  }
  return pageModel;
 }
  
 /**
  * 取得總記錄數
  * @param conn
  * @return
  */
 private int getTotalRecords(Connection conn)
 throws SQLException {
  String sql = "select count(*) from t_user where user_id <> 'root'";
  PreparedStatement pstmt = null;
  ResultSet rs = null;
  int count = 0;
  try {
   pstmt = conn.prepareStatement(sql);
   rs = pstmt.executeQuery();
   rs.next();
   count = rs.getInt(1);
  }finally {
   DbUtil.close(rs);
   DbUtil.close(pstmt);
  }
  return count;
 }
  
 /**
  * 修改用戶
  * @param user
  */
 public void modifyUser(User user) {
  StringBuilder sbSql = new StringBuilder();
  sbSql.append("update t_user ")
  .append("set    user_name   = ?, ")
         .append("password    = ?, ")
         .append("contact_tel = ?, ")
         .append("email       = ? ")
  .append("where  user_id     = ? ");
  Connection conn = null;
  PreparedStatement pstmt = null;
  try {
   conn = DbUtil.getConnection();
   pstmt = conn.prepareStatement(sbSql.toString());
   pstmt.setString(1, user.getUserName());
   pstmt.setString(2, user.getPassword());
   pstmt.setString(3, user.getContactTel());
   pstmt.setString(4, user.getEmail());
   pstmt.setString(5, user.getUserId());
   pstmt.executeUpdate();
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   DbUtil.close(pstmt);
   DbUtil.close(conn);
  }
 }
  
 /**
  * 根據用戶代碼刪除
  * @param userId
  */
 public void delUser(String userId) {
  String sql = "delete from t_user where user_id=?";
  Connection conn = null;
  PreparedStatement pstmt = null;
  try {
   conn = DbUtil.getConnection();
   pstmt = conn.prepareStatement(sql);
   pstmt.setString(1, userId);
   pstmt.executeUpdate();
  }catch(SQLException e) {
   e.printStackTrace();
  }finally {
   DbUtil.close(pstmt);
   DbUtil.close(conn);
  }
 }
}