BaseDao类

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package dao;

import java.sql.Connection;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import javax.naming.Context;
import javax.naming.InitialContext;
import javax.naming.NamingException;
import javax.sql.DataSource;

public class BaseDao {
//属性
public Connection conn;
public PreparedStatement pstmt;
public ResultSet rs;
//获得连接
public Connection getConnection(){
  try {
   //初始化上下文
   Context ctx = new InitialContext();
   //获取与逻辑名相同的数据源对象
   DataSource ds =
             (DataSource)ctx.lookup("java:comp/env/jdbc/MySQLDB");
   conn = ds.getConnection();
  } catch (NamingException e) {
   // TODO Auto-generated catch block
   e.printStackTrace();
  }catch(SQLException e){
   e.printStackTrace();
  }
  return conn;
}
// 增删改
public int executeUpdate(String sql,Object[] parames){
  int row = 0;
  conn = getConnection();//获得连接
  try {
   pstmt = conn.prepareStatement(sql);
   //填充占位符
   for(int i=0;i<parames.length;i++){
    pstmt.setObject(i+1, parames[i]);
   }
   row = pstmt.executeUpdate();
  } catch (SQLException e) {
   e.printStackTrace();
  }finally{
   close();
  }
  return row;
}
//查询方法
public ResultSet executeSQL(String sql,Object[] params){
  //获得连接
  conn = getConnection();

  try{
   pstmt = conn.prepareStatement(sql);
   for(int i = 0;i<params.length;i++){
    pstmt.setObject((i+1), params[i]);
   }
   rs = pstmt.executeQuery();
  }catch(SQLException e){
   e.printStackTrace();
   return null;
  }
  return rs;
}

//断开连接
public void close(){
  try {
   if (rs != null) {
    rs.close();
   }
   if (pstmt != null) {
    pstmt.close();
   }
   if (conn != null) {
    conn.close();
   }

  } catch (SQLException e) {
   e.printStackTrace();
  }
}
}

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