jsp代码实例第243课

code243.java

package pack06;

import java.sql.Connection;
import java.sql.ResultSet;
import java.sql.Statement;
import java.util.ArrayList;

//模拟UsersDao类
public class code243
{
  //新增插入
  public boolean insert(code241 user)
  {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try
    {
      conn = code242.getConnection();
      stmt = conn.createStatement();
      String sql = "insert into user(user_name) values('"
          + user.getUserName() + "')";
      int num = stmt.executeUpdate(sql);
      if (num > 0)
      {
        return true;
      }
      return false;
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    finally 
    {
      code242.release(rs, stmt,conn);
    }
    return false;
  }

  //检索全部
  public ArrayList<code241> findAll()
  {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    ArrayList<code241> list = new ArrayList<>();
    try
    {
      conn = code242.getConnection();
      stmt = conn.createStatement();
      String sql = "select * from user";
      rs = stmt.executeQuery(sql);
      while (rs.next())
      {
        code241 user = new code241();
        user.setId(rs.getInt("user_id"));
        user.setUserName(rs.getString("user_name"));
        list.add(user);

      }
      return list;
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    finally 
    {
      code242.release(rs, stmt,conn);
    }
    return null;
  }

  //根据id检索
  public code241 find(int id)
  {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try
    {
      conn = code242.getConnection();
      stmt = conn.createStatement();
      String sql = "select * from user where user_id=" + id;
      rs = stmt.executeQuery(sql);
      while (rs.next())
      {
        code241 user = new code241();
        user.setId(rs.getInt("user_id"));
        user.setUserName(rs.getString("user_name"));
        return user;
      }
      return null;
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    finally 
    {
      code242.release(rs, stmt,conn);
    }
    return null;
  }

  //删除
  public boolean delete(int id)
  {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try
    {
      conn = code242.getConnection();
      stmt = conn.createStatement();
      String sql = "delete from user where user_id=" + id;
      int num = stmt.executeUpdate(sql);
      if (num > 0)
      {
        return true;
      }
      return false;
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    finally 
    {
      code242.release(rs, stmt, conn);
    }
    return false;
  }

  //修改
  public boolean update(code241 user)
  {
    Connection conn = null;
    Statement stmt = null;
    ResultSet rs = null;
    try
    {
      conn = code242.getConnection();
      stmt = conn.createStatement();
      String sql = "update user set user_name='" + user.getUserName() +"' where user_id=" + user.getId();
      int num = stmt.executeUpdate(sql);
      if (num > 0)
      {
        return true;
      }
      return false;
    } catch (Exception e)
    {
      e.printStackTrace();
    }
    finally 
    {
      code242.release(rs, stmt, conn);
    }
    return false;
  }
}