basedao.java

网上购物系统

package eshopsys.tools.base;

import java.sql.ResultSet;
import java.sql.SQLException;
import java.sql.Date;
import java.sql.Connection;
import java.sql.Statement;
import java.sql.PreparedStatement;
import eshopsys.tools.database.DataBaseTool;

public abstract class BaseDao {
 protected Connection con=null;
 public BaseDao()
 {
	 try {
		con=DataBaseTool.getConnection();
	} catch (SQLException e) {
		e.printStackTrace();
	}
 }
  //把结果集包装成实体对象数组，BaseDao的子类必须实现该方法
  protected abstract BaseEntity[] pack(ResultSet resultset) throws SQLException;
//根据传入的sql语句进行查询
  public ResultSet selectRSByQueryString(String sql) throws
 SQLException {
    Statement ps = null;
    ResultSet rs = null;
    try {
      ps = con.createStatement();
      rs = ps.executeQuery(sql);
      //将结果集包装成实体对象数组
    }
catch (Exception e) {
//将捕获的异常抛出，最终在视图层处理
throw new SQLException("执行数据库查找操作的过程中发生异常 : " + 
e.getMessage());
    }
    //finally {
      //关闭各项数据库资源
      //DataBaseTool.close(rs, ps, null);
    //}
   return rs;
}
//////////////////////////////////////////////////////////////////////////
  //根据传入的sql语句进行查询
  public BaseEntity[] selectArrayByQueryString( String sql) throws
 SQLException {
    BaseEntity[] entitys = null;
    Statement ps = null;
    ResultSet rs = null;
    try {
      ps = con.createStatement();
      rs = ps.executeQuery(sql);
      //将结果集包装成实体对象数组
      entitys = pack(rs);
    }
catch (Exception e) {
//将捕获的异常抛出，最终在视图层处理
throw new SQLException("执行数据库查找操作的过程中发生异常 : " + 
e.getMessage());
    }
    finally {
      //关闭各项数据库资源
      DataBaseTool.close(rs, ps, null);
    }
    return entitys;
}
//////////////////////////////////////////////////////////////////////////
  //根据数据库中的表名和自增长ID查询记录
  public BaseEntity selectById(String tableName,String properyName, int id) throws
SQLException {
    BaseEntity entity = null;
    PreparedStatement ps = null;
    ResultSet rs = null;
    StringBuffer buffer = new StringBuffer();
    try {
      // 构造查询sql语句
      buffer.append("SELECT * FROM " + tableName);
      buffer.append(" WHERE"+" "+properyName+" = " + id);
      ps = con.prepareStatement(buffer.toString());
      //执行查询
      rs = ps.executeQuery();
      BaseEntity[] entitys = (BaseEntity[]) pack(rs);
      if (entitys != null) {
        entity = entitys[0];
      }
    }
    catch (Exception e) {
      //将捕获的异常抛出，最终在视图层处理
      throw new SQLException(
"在表 " + tableName + " 中根据自增长ID进行查找的过程中发生异常 : " +                             e.getMessage());
    }
    finally {
      DataBaseTool.close(rs, ps, null);
    }
    return entity;
  }

    //根据表名和自增长ID删除一条记录
	public int deleteById(String tableName, String properyName, int id) throws 
SQLException {
	  PreparedStatement ps = null;
	  StringBuffer buffer = new StringBuffer();
	  try {
	    //构早删除sql语句
	    buffer.append("DELETE FROM " + tableName);
	    buffer.append(" WHERE"+" "+properyName+" = " + id);
	    ps = con.prepareStatement(buffer.toString());
	    //执行sql语句
	    ps.executeUpdate();
	  }
	  catch (Exception e) {
//将捕获的异常抛出，最终在视图层处理
	    throw new SQLException("删除数据时发生异常 : " + e.getMessage());
	  }
	  finally {
	    DataBaseTool.close(ps);
	  }
	  return id;
	}
	
//根据表名删除指定表的所有记录
public void deleteAllRecords(String tableName) throws 
SQLException {
	  PreparedStatement ps = null;
	  StringBuffer buffer = new StringBuffer();
	  try {
	    //构早删除sql语句
	    buffer.append("DELETE  FROM " + tableName);
	    ps = con.prepareStatement(buffer.toString());
	    //执行sql语句
	    ps.executeUpdate();
	  }
	  catch (Exception e) {
//将捕获的异常抛出，最终在视图层处理
	    throw new SQLException("删除数据时发生异常 : " + e.getMessage());
	  }
	  finally {
	    DataBaseTool.close(ps);
	  }
	}
//////////////////////////////////////////////////////////////////////////
//根据表名删除指定表的所有记录
public int getMaxPrimaryId(String tableName, String properyName) throws 
SQLException {
	  int MaxId=0;
	  PreparedStatement ps = null;
	  StringBuffer buffer = new StringBuffer();
	  try {
	    //构早删除sql语句
	    buffer.append("SELECT MAX("+properyName+") as maxid  FROM " + tableName);
	    ps = con.prepareStatement(buffer.toString());
	    //执行sql语句
	    ResultSet rs=ps.executeQuery();
	    if(rs.next())
	    {
	    	MaxId=rs.getInt("maxid");
	    }
	    
	  }
	  catch (Exception e) {
//将捕获的异常抛出，最终在视图层处理
	    throw new SQLException("删除数据时发生异常 : " + e.getMessage());
	  }
	  finally {
	    DataBaseTool.close(ps);
	  }
	  
	  return MaxId+1;
	}
//////////////////////////////////////////////////////////////////////////
public void CloseConnection()
{
    DataBaseTool.close(con);
}
public void beginTransaction()throws Exception 
{
	 if (con == null) {
	      throw new Exception("不能为一个空连接开启事务!");
	    }
	    else {
	      con.setAutoCommit(false);
	      return;
	    }
}
public void endTransaction(boolean success) throws Exception 
{
	if (con == null) {
	      throw new Exception("不能为一个空连接结束事务!");
	    }
	    if (success) {
	      con.commit();
	    }
	    else {
	      con.rollback();
	 }
}

//////////////////////////////////////////////////////////////////////////
}