java通用DAO

 

package org.gaoyoubo.dao;

import java.sql.*;
import java.util.*;

import javax.servlet.jsp.jstl.sql.*;

public class CommanDao {
    private Connection con;
    private String sql;
    private List parameters;
    //设置连接
    public void setCon(Connection con) {
        this.con = con;
    }
    //设置sql语句；
    public void setSql(String sql) {
        this.sql = sql;
    }
    //设置sql语句参数；
    public void setParameters(List aparametersrameters) {
        this.parameters = aparametersrameters;
    }
    
    /**
     * 执行查询；
     * @return
     */
    public Result  executeQuery(){
        Result result = null;
        ResultSet rs = null;
        PreparedStatement pstmt = null;
        
        
        try {
            //如果sql语句有参数；
            if(parameters != null && parameters.size() > 0){
                pstmt = con.prepareStatement(sql);
                setParameters(pstmt, parameters);
                rs = pstmt.executeQuery();
            }
            //如果没有参数；
            else{
                pstmt = con.prepareStatement(sql);
                rs = pstmt.executeQuery();
            }
        } catch (SQLException e) {
            // TODO: handle exception
            e.printStackTrace();
        }
        //将ResultSet转换成Result;
        result = ResultSupport.toResult(rs);        
        return result;
    }
    
    /**
     * 执行更新；
     * @return 返回受影响行数；
     */
    public int executeUpdate(){
        int noOfRows = 0;
        ResultSet rs = null;
        PreparedStatement pstmt = null;
        try {
            //如果参数不为空；
            if(parameters != null && parameters.size() > 0){
                pstmt = con.prepareStatement(sql);
                setParameters(pstmt, parameters);
                noOfRows = pstmt.executeUpdate();
            }
            else{
                pstmt = con.prepareStatement(sql);
                noOfRows = pstmt.executeUpdate();
            }
        } catch (SQLException e) {
            // TODO Auto-generated catch block
            e.printStackTrace();
        }
        return noOfRows;
    }
    
    
    /**
     * 方法，为sql语句设置参数；
     * @param pstmt 指令
     * @param parameters 参数集合；
     * @throws SQLException 
     */
    private void setParameters(PreparedStatement pstmt,List parameters) throws SQLException{
        for (int i = 0; i < parameters.size(); i++) {
            Object v = parameters.get(i);
            pstmt.setObject(i+1, v);
        }
    }
    
}